Re: [time-nuts] Low noise power supplies

[Charles Steinmetz]

Chris wrote:

Just practical question.. How would one measure noise at this 
level?  If I were evaluate this what would I need?


Generally, one starts with an extremely low noise amplifier.  Note 
that isolating the very low frequency AC components from the DC 
component is a substantial difficulty (we are interested in AC noise 
well below 1 Hz).  For example:




See also:

Linear Technology Application Notes 124 and 83

Bruno Neri, et al., Ultra Low-Noise Preamplifier for Low-Frequency 
Noise Measurements in Electron Devices, IEEE Transactions On 
Instrumentation And Measurement, Vol. 40. No. I. February 1991


Felix A. Levinzon, Ultra-Low-Noise High-Input Impedance Amplifier for 
Low-Frequency Measurement Applications, IEEE Transactions On Circuits 
And Systems - I: Regular Papers, Vol. 55, No. 7, August 2008


Some spectrum analyzers with cross-correlation capabilities can get 
you in the ballpark if you let them average long enough, although you 
are much better off if you use an ELN amplifier there, too.


Best regards,

Charles



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Re: [time-nuts] Low noise power supplies?

[Ulrich Bangert]

Charles et al,

http://www.pst.netii.net/spice/ripple/ripple.htm

holds some interesting spice simulations of various refinement techniques.

Best regards
Ulrich Bangert

> -Ursprungliche Nachricht-
> Von: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] Im Auftrag von Charles P. 
> Steinmetz
> Gesendet: Freitag, 1. Februar 2013 18:35
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Low noise power supplies?
> 
> 
> Joe wrote:
> 
> >Back when I was in product engineering there was a VCO design that
> >used a "superfilter" circuit. It consisted of a pass transistor and 
> >a filter cap from base to ground. The gain of the transistor 
> >multiplied the effective capacitance. I have not seen this 
> configuration since.
> 
> They are often called "capacitance multipliers" and are popular with 
> (among others) audio designers as low-noise supplies for low-level 
> circuits (moving coil head amps, RIAA stages, etc.).  They are best 
> used following an active regulator.  If the capacitor is 
> electrolytic, it needs to be chosen very carefully so that leakage 
> current noise doesn't spoil the effort.  Also, it is best to use a 
> voltage divider on the base to give the transistor a bit of headroom 
> (i.e., base voltage should be a volt or so lower than collector 
> voltage, not the same as the collector voltage as happens when there 
> is just a pull-up resistor on the base).
> 
> Best regards,
> 
> Charles
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] Low noise power supplies?

[lists]

Well the Tek current probe that goes in the power supply wasn't low cost. They 
also had a nice bench supply that went in the box. But a lot of the instruments 
weren't so fancy.
 
-Original Message-
From: "Max Robinson" 
Sender: time-nuts-boun...@febo.com
Date: Fri, 1 Feb 2013 13:39:14 
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement
    
Subject: Re: [time-nuts] Low noise power supplies?

Well, I stand corrected.  Weren't the TM 500 instruments marketed as low 
cost?

Regards.

Max.  K 4 O DS.

Email: m...@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
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- Original Message - 
From: "David" 
To: "Discussion of precise time and frequency measurement" 

Sent: Thursday, January 31, 2013 11:10 PM
Subject: Re: [time-nuts] Low noise power supplies?


>I have seen it used in a couple of Tektronix TM500 instruments but the
> purpose may have been to generate a lower voltage power supply rail
> instead of noise reduction.  Tektronix often added LC sections on
> their switching power supply outputs and distributed smaller LC
> sections to prevent coupling between different circuits.
>
> On Thu, 31 Jan 2013 22:12:42 -0600, "Max Robinson"
>  wrote:
>
>>You haven't seen it used because it doesn't work very well.  It appeared 
>>in
>>a few pieces of Heathkit equipment but I don't think HP or Tek used it at
>>all.  Any AC component of base to collector voltage has a small but 
>>definite
>>effect on Vbe which transfers voltage in the reverse direction from
>>collector to emitter even though the base is held at AC ground.  A three
>>terminal regulator does a better job of suppressing ripple from a power
>>supply.
>>
>>Regulators use a zener diode as the reference and there are circuits in
>>which a zener is used as a noise source.  What does that tell you?  The
>>quietest power supply is an analog regulator followed by one or more RC
>>filter sections.  The inductor in an LC filter is likely to pick up more 
>>hum
>>and noise than it filters out.  My presumption is that a low noise power
>>supply is likely to be providing a small amount of power to the load and
>>load regulation is probably not a problem.
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Re: [time-nuts] Low noise power supplies?

[Max Robinson]

This is a keeper.  Note the strong peak at 60 Hz for the unfiltered 
darlington.


Regards.

Max.  K 4 O DS.

Email: m...@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
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- Original Message - 
From: "John Miles" 
To: "'Discussion of precise time and frequency measurement'" 


Sent: Friday, February 01, 2013 12:03 AM
Subject: Re: [time-nuts] Low noise power supplies?



Awhile back I ran some baseband plots of various supplies with an HP 3048A
(image attached).  In my experience measuring actual OCXOs, an LM317T or
LM338K is quiet enough to avoid influencing oscillator PN.  With these
variable-voltage parts, you can bypass the reference pin for some 
additional

improvement, but I don't believe I did that for these plots.

It's easy to spot the difference between a 7812/7815 and an LM317T (see 
red

versus green/white traces).   As a lazy approach, try measuring the
oscillator with both a 78XX and an LM317T.  Because the 78XX is about 10 
dB
noisier across most of the spectrum, If you don't see a difference, you 
can

assume that further optimization is pointless.  Near 1 Hz this call may be
questionable.

If you don't need an LDO, don't use one.  If you do, use the quietest part
you can find.  The best LDOs seem to be about as quiet as an ordinary
LM317T.

I've mentioned before that you need to be careful with large LC filters
downstream of the regulator.   A good power source will exhibit a low
impedance at ALL offsets of interest.

You sometimes see NIST circuits where the power is conditioned by a
Darlington emitter follower whose base is fed with an RC-filtered Zener
diode.  The purple and orange traces are pretty informative with regard to
that approach.  On the orange trace, where the only filtering is the RC
network between the Zener and the base, notice how the noise becomes worse
than all of the other sources below 10 Hz.  Here, the RC filter on the 
Zener

becomes less effective and the Darlington pair obligingly amplifies the
diode noise.

An additional LC filter after the regulator may have the effect of herding
the entire noise spectrum into a high-Q peak, even though the LC corner
frequency is much higher than the RC filter in the base circuit (violet
trace).   Depending on your OCXO's supply rejection characteristics this
could be a good thing or a bad thing.

Finally, make sure the OCXO has good RF bypassing where its power supply 
pin
enters the case.  If in doubt, solder a 0.1 uF ceramic right at the point 
of

entry.  I've seen $2000 Wenzels that didn't bother doing this.  I'm sure
they looked good in a screen room.

-- john
Miles Design LLC



-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-
boun...@febo.com] On Behalf Of Richard (Rick) Karlquist
Sent: Wednesday, January 30, 2013 6:17 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Low noise power supplies?


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies?

[Max Robinson]

Well, I stand corrected.  Weren't the TM 500 instruments marketed as low 
cost?


Regards.

Max.  K 4 O DS.

Email: m...@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Woodworking site 
http://www.angelfire.com/electronic/funwithtubes/Woodworking/wwindex.html

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- Original Message - 
From: "David" 
To: "Discussion of precise time and frequency measurement" 


Sent: Thursday, January 31, 2013 11:10 PM
Subject: Re: [time-nuts] Low noise power supplies?



I have seen it used in a couple of Tektronix TM500 instruments but the
purpose may have been to generate a lower voltage power supply rail
instead of noise reduction.  Tektronix often added LC sections on
their switching power supply outputs and distributed smaller LC
sections to prevent coupling between different circuits.

On Thu, 31 Jan 2013 22:12:42 -0600, "Max Robinson"
 wrote:

You haven't seen it used because it doesn't work very well.  It appeared 
in

a few pieces of Heathkit equipment but I don't think HP or Tek used it at
all.  Any AC component of base to collector voltage has a small but 
definite

effect on Vbe which transfers voltage in the reverse direction from
collector to emitter even though the base is held at AC ground.  A three
terminal regulator does a better job of suppressing ripple from a power
supply.

Regulators use a zener diode as the reference and there are circuits in
which a zener is used as a noise source.  What does that tell you?  The
quietest power supply is an analog regulator followed by one or more RC
filter sections.  The inductor in an LC filter is likely to pick up more 
hum

and noise than it filters out.  My presumption is that a low noise power
supply is likely to be providing a small amount of power to the load and
load regulation is probably not a problem.

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Re: [time-nuts] Low noise power supplies?

[Fabio Eboli]

Sorry, Poul-Henning Kamp, I answered directly
to your mail address, I repost it here...

Il 2013-02-01 18:09 Poul-Henning Kamp ha scritto:

Content-Type: text/plain; charset=ISO-8859-1

In message <2bf4f4e8c8207ae0f94a7e1a1e63c...@quipo.it>, Fabio Eboli 
writes:



Il 2013-01-31 06:42 Mark Sims ha scritto:

A123 20Ah LiFePO4 cells have an internal resistance in the milliohm
range. [...]


Low internal resistance in batteries is an indicator of low noise,
but not a guarantee of low noise.


I have no reason to disagree with your statement :)

I was agreeing with Mark about the fact that there
are "new" chemistries with low internal resistance,
and nice characteristics like low cost, availability
and low self discharge, and that some Li-ion can be
built to be one of those.



For instance in wet lead-acid cells, turbulence in the liquid as
the density changes can lead to low-frequency noise, which 
incidentally

sounds a lot like a pot of stew simmering.


It would be interesting to see if there
are references about noise in the li chemistries.

Fabio.
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Re: [time-nuts] Low noise power supplies?

[Charles P. Steinmetz]

Joe wrote:

Back when I was in product engineering there was a VCO design that 
used a "superfilter" circuit. It consisted of a pass transistor and 
a filter cap from base to ground. The gain of the transistor 
multiplied the effective capacitance. I have not seen this configuration since.


They are often called "capacitance multipliers" and are popular with 
(among others) audio designers as low-noise supplies for low-level 
circuits (moving coil head amps, RIAA stages, etc.).  They are best 
used following an active regulator.  If the capacitor is 
electrolytic, it needs to be chosen very carefully so that leakage 
current noise doesn't spoil the effort.  Also, it is best to use a 
voltage divider on the base to give the transistor a bit of headroom 
(i.e., base voltage should be a volt or so lower than collector 
voltage, not the same as the collector voltage as happens when there 
is just a pull-up resistor on the base).


Best regards,

Charles






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Re: [time-nuts] Low noise power supplies?

[Poul-Henning Kamp]

Content-Type: text/plain; charset=ISO-8859-1

In message <2bf4f4e8c8207ae0f94a7e1a1e63c...@quipo.it>, Fabio Eboli writes:

>Il 2013-01-31 06:42 Mark Sims ha scritto:
>> A123 20Ah LiFePO4 cells have an internal resistance in the milliohm
>> range. [...]

Low internal resistance in batteries is an indicator of low noise,
but not a guarantee of low noise.

For instance in wet lead-acid cells, turbulence in the liquid as
the density changes can lead to low-frequency noise, which incidentally
sounds a lot like a pot of stew simmering.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Low noise power supplies?

[lists]

Ok, but open loop as I described?

I bicmos design, there are two common "junk" buffers. The junkiest (sp?) is 
going up a PNP and down a NPN. No feedback. You live with the vbe mismatch. 
Next up the food chain is the long tail pair (diff amp) with emitter follower. 
With one gain stage, it is reasonable stable. 

-Original Message-
From: "John Miles" 
Sender: time-nuts-boun...@febo.com
Date: Fri, 1 Feb 2013 01:30:24 
To: 'Discussion of precise time and frequency measurement'
Reply-To: Discussion of precise time and frequency measurement
        
Subject: Re: [time-nuts] Low noise power supplies?

> Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE
> drops?
> 
> Any of these circuits where the output transistor is in an emitter
> follower configuration will have its noise effected by the load current,
> since that current directly effects the output transistor
transconductance.

The load in all cases was a couple hundred mA worth of resistance at the
voltage in question, as I recall.  It's been a few years since I captured
these plots.

The Zeners were just whatever parts came to hand, 1N474x parts basically.  I
didn't care about the 1.4V drop across the Darlington, just the resulting
noise.

-- john
Miles Design LLC



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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

If you use an electrolytic cap on the base (tantalum or what ever) the
leakage current will mess up the output a bit. It does *eventually* die down
some, but you may have to wait for days...

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of M. Simon
Sent: Friday, February 01, 2013 9:11 AM
To: time-nuts@febo.com; jleik...@leikhim.com
Subject: [time-nuts] Low noise power supplies?

Joe,

I'm using that in my low power (150ma) supplies. I add a zener to the base
(darlington) circuit for pre-regulation. Since I'm doing a line operated
linear supply the fall off of gain with frequency is not  of too much
concern.

Once I finish testing (I have boards in hand - I need to order parts)  I
will publish. 

Simon


Message: 6
Date: Thu, 31 Jan 2013 15:39:02 -0500
From: Joe Leikhim 
To: time-nuts@febo.com
Subject: [time-nuts]  Low noise power supplies?
Message-ID: <510ad666.8090...@leikhim.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Back when I was in product engineering there was a VCO design that used 
a "superfilter" circuit. It consisted of a pass transistor and a filter 
cap from base to ground. The gain of the transistor multiplied the 
effective capacitance. I have not seen this configuration since.

-- 
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

 



Engineering is the art of making what you want from what you can get at a
profit.
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[time-nuts] Low noise power supplies?

[M. Simon]

Joe,

I'm using that in my low power (150ma) supplies. I add a zener to the base 
(darlington) circuit for pre-regulation. Since I'm doing a line operated linear 
supply the fall off of gain with frequency is not  of too much concern.

Once I finish testing (I have boards in hand - I need to order parts)  I will 
publish. 

Simon


Message: 6
Date: Thu, 31 Jan 2013 15:39:02 -0500
From: Joe Leikhim 
To: time-nuts@febo.com
Subject: [time-nuts]  Low noise power supplies?
Message-ID: <510ad666.8090...@leikhim.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Back when I was in product engineering there was a VCO design that used 
a "superfilter" circuit. It consisted of a pass transistor and a filter 
cap from base to ground. The gain of the transistor multiplied the 
effective capacitance. I have not seen this configuration since.

-- 
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

 



Engineering is the art of making what you want from what you can get at a 
profit.
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Re: [time-nuts] Low noise power supplies?

[Fabio Eboli]

Hello, interesting discussion about noise.
It's all way over my knowledge, so my contribution
to discussion maybe is only noise :)

Re batteries I agree with Mark, see below:

Il 2013-01-31 06:42 Mark Sims ha scritto:

A123 20Ah LiFePO4 cells have an internal resistance in the milliohm
range.  Their M1 26650 format cells are around 8 milliohms.  Most 
high

capacity (>3000 mAh) 18650 style lithium cells are around 10-15
milliohms.


I made some tests of high rate RC batteries,
and their internal resistance seem to be below 10mOhm
These are Li-ion pouch cells, their selfdischarge
seem very low, but I dont have figures for this.
Their cost is very low, and are used for RC airplanes
or cars, only thing I'm expecting is that they
will age and their internal resistance (and capacity)
probably will worsen after some time.
This is a graph of a 3-cell battery of 1.8Ah capacity,
charged and discharged at 3.6A and 7.2A (red and blue
curves):

Here tested up to maximum declared rate:


I report this here about noise, because I
remember that while I was charging and discharging
them, I was watching with awe the voltmeter
stable readings. The power supply/load
was an HP6632B and the meter a keithley 2015,
the meter reading was stable up to last digit
(10uV over 10-11V)and counting digit by digit up
while charging or down while discharging, "no missing
codes" sort of thing :)
It was like watching a counter instead of a voltmeter.
So I was wondering what could be the real noise
of a chemical battery. Reading this discussion
I'm learning that the batteries can be low noise
voltage sources.

Thanks,
Fabio.
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Re: [time-nuts] Low noise power supplies?

[Ulrich Bangert]

Linear Technology application note 83

"Performance Verification of Low Noise, Low Dropout Regulators"

holds some interesting information. I am however unsure whether what was low
noise in 2000 is still low noise in 2013

Best regards
Ulrich Bangert

> -Ursprungliche Nachricht-
> Von: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] Im Auftrag von Bob Camp
> Gesendet: Freitag, 1. Februar 2013 13:38
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Low noise power supplies?
> 
> 
> Hi
> 
> The circuit I described, is (as stated) quiet down to 100 Hz. 
> It's 3 db bandwidth is well below 10 Hz with the 47 uF cap. 
> If you need it quiet down to 10 Hz or 0.1 Hz, you 
> will need to buy a few more caps. It's still not rocket science.
> 
> For most OCXO or atomic standard testing applications out 
> there, 10 Hz is low enough. 
> 
> Bob
> 
> On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz 
>  wrote:
> 
> > Bob wrote:
> > 
> >> An AD 797, a couple of metal film resistors, and a fairly 
> large (say 
> >> 47 uf) plastic cap work pretty well.
> > 
> > The band from 10 Hz down to 0.1 or 0.01 Hz is generally 
> important when 
> > testing oscillators.  To keep the 797 input noise density 
> below a few 
> > nV per root Hz, the terminations must have very low 
> resistance.  With 
> > such low resistance, a 47 uF cap won't even get you to 10 Hz, much 
> > less 0.1 or 0.01 Hz.
> > 
> > One more thought: Many oscillators have internal regulators 
> that are 
> > not nearly as good as what you can build.  No sense using 
> an external 
> > supply with 5 nV per root Hz noise density if it will be 
> re-regulated 
> > inside the oscillator by a circuit that has a noise density 
> of 250 nV 
> > per root Hz.
> > 
> > Best regards,
> > 
> > Charles
> > 
> > 
> > 
> > 
> > ___
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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

The circuit I described, is (as stated) quiet down to 100 Hz. It's 3 db 
bandwidth is well below 10 Hz with the 47 uF cap. If you need it quiet down to 
10 Hz or 0.1 Hz, you will need to buy a few more caps. It's still not 
rocket science.

For most OCXO or atomic standard testing applications out there, 10 Hz is low 
enough. 

Bob

On Jan 31, 2013, at 9:41 PM, Charles P. Steinmetz 
 wrote:

> Bob wrote:
> 
>> An AD 797, a couple of metal film resistors, and a fairly large (say 47 uf) 
>> plastic cap work pretty well.
> 
> The band from 10 Hz down to 0.1 or 0.01 Hz is generally important when 
> testing oscillators.  To keep the 797 input noise density below a few nV per 
> root Hz, the terminations must have very low resistance.  With such low 
> resistance, a 47 uF cap won't even get you to 10 Hz, much less 0.1 or 0.01 Hz.
> 
> One more thought: Many oscillators have internal regulators that are not 
> nearly as good as what you can build.  No sense using an external supply with 
> 5 nV per root Hz noise density if it will be re-regulated inside the 
> oscillator by a circuit that has a noise density of 250 nV per root Hz.
> 
> Best regards,
> 
> Charles
> 
> 
> 
> 
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Re: [time-nuts] Low noise power supplies?

[Robert Atkinson]

Hi Bert,
No need to block the DC. These instruments already have DC blocks (and a 
switchable low current DC sink to "hold" the line from the exchange) because 
the telephone line has a DC voltage of typically 48V on it already.
For comparison I just use 600 ohm termination and dBm, dBmV can be calculated 
or use a look-up table. To compare a batch you can zero the meter on the first 
or known good unit and just read the delta.
 
Robert G8RPI.


From: Burt I. Weiner 
To: time-nuts@febo.com 
Sent: Thursday, 31 January 2013, 19:19
Subject: [time-nuts] Low noise power supplies?


Bob,

I have a pair of HP-3551A's*.  I'm very familiar with making transmission lines 
measurements, and it seems that measuring power supply noise would be the same, 
except that you want to block the DC from the input of the instrument.  What 
has your procedure been and what numbers have you come up with?  Since these 
instruments read in dBm0, do you reference from the supply's voltage and then 
convert to mV (difference)?

* One that I picked up off eBay for $75.00 looks new and came with the complete 
manual, and the battery will run it most of the day.

Thanks,

Burt, K6OQK


> Subject: Re: [time-nuts] Low noise power supplies?
> 
> A non-standard but repeatable way to measure power supply noise is to use a 
> Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551
> (2)A. These were intended for use in pairs to assess analog telephone lines 
> for data use. As well as an AF generator, frequency counter, amplifier, 
> monitor speaker and level meter they will measure broadband noise. Being 
> designed for POTS they will also withstand at least 50V DC at the input while 
> measuring the noise. You can also apply internal filters if required. The 
> last digit designates a North American? (BELL) or European (CCITT) standard 
> unit, but broadband noise is the same. They can be picked up really cheaply 
> now (list was$3000-$5000) and make a nice compact audio test set.
> 
> Robert G8RPI.
> 
> 
> 

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 
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Re: [time-nuts] Low noise power supplies?

[Sarah White]

Bob Camp, Thursday, January 31 11:36 AM (Local NY time):
((...snip...))
> With a good enough voltmeter you could carry the analogy one step further
> and compute an ADEV like number on the output voltage. I suspect that's
> carrying things a bit far.

No, I disagree. That's not carrying things nearly far enough.

I really think we should figure out a reliable methodology for this sort
of thing. This is time nuts after all, so perhaps some time/frequency
applications might end up needing sub-nanovolt regulation (and there are
those whom might simply "need" it because they're nuts)


Tom Van Baak, Thursday, January 31, 2013 9:43 AM (Local NY time):
((...snip...))
> I was never quite satisfied with the outcome of comparing a half dozen power
> supplies this way:
> http://www.leapsecond.com/pages/tbolt/noise.htm
> 
> We have rigorous ways to compare and report oscillator performance; both as
> numbers and as plots. Is there something equivalent for power supplies?

Thanks Tom.

I found that writeup about various power supplies rather useful. I'm
doing some research and development for power supplies right now, and
hope to come up with something completely nuts by the time I'm ready to
go from learning how to work with thunderbolts / GPS Disciplined OCXO to
something exotic which, today, might be far over my head.

--Sarah
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Re: [time-nuts] Low noise power supplies?

[John Miles]

> Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE
> drops?
> 
> Any of these circuits where the output transistor is in an emitter
> follower configuration will have its noise effected by the load current,
> since that current directly effects the output transistor
transconductance.

The load in all cases was a couple hundred mA worth of resistance at the
voltage in question, as I recall.  It's been a few years since I captured
these plots.

The Zeners were just whatever parts came to hand, 1N474x parts basically.  I
didn't care about the 1.4V drop across the Darlington, just the resulting
noise.

-- john
Miles Design LLC



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Re: [time-nuts] Low noise power supplies?

[gary]

Are 4 and 5 regulated? Or is the zener picked to compensate for the VBE 
drops?


Any of these circuits where the output transistor is in an emitter 
follower configuration will have its noise effected by the load current, 
since that current directly effects the output transistor transconductance.


On 1/31/2013 10:03 PM, John Miles wrote:

Awhile back I ran some baseband plots of various supplies with an HP 3048A
(image attached).  In my experience measuring actual OCXOs, an LM317T or
LM338K is quiet enough to avoid influencing oscillator PN.  With these
variable-voltage parts, you can bypass the reference pin for some additional
improvement, but I don't believe I did that for these plots.

It's easy to spot the difference between a 7812/7815 and an LM317T (see red
versus green/white traces).   As a lazy approach, try measuring the
oscillator with both a 78XX and an LM317T.  Because the 78XX is about 10 dB
noisier across most of the spectrum, If you don't see a difference, you can
assume that further optimization is pointless.  Near 1 Hz this call may be
questionable.

If you don't need an LDO, don't use one.  If you do, use the quietest part
you can find.  The best LDOs seem to be about as quiet as an ordinary
LM317T.

I've mentioned before that you need to be careful with large LC filters
downstream of the regulator.   A good power source will exhibit a low
impedance at ALL offsets of interest.

You sometimes see NIST circuits where the power is conditioned by a
Darlington emitter follower whose base is fed with an RC-filtered Zener
diode.  The purple and orange traces are pretty informative with regard to
that approach.  On the orange trace, where the only filtering is the RC
network between the Zener and the base, notice how the noise becomes worse
than all of the other sources below 10 Hz.  Here, the RC filter on the Zener
becomes less effective and the Darlington pair obligingly amplifies the
diode noise.

An additional LC filter after the regulator may have the effect of herding
the entire noise spectrum into a high-Q peak, even though the LC corner
frequency is much higher than the RC filter in the base circuit (violet
trace).   Depending on your OCXO's supply rejection characteristics this
could be a good thing or a bad thing.

Finally, make sure the OCXO has good RF bypassing where its power supply pin
enters the case.  If in doubt, solder a 0.1 uF ceramic right at the point of
entry.  I've seen $2000 Wenzels that didn't bother doing this.  I'm sure
they looked good in a screen room.

-- john
Miles Design LLC



-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-
boun...@febo.com] On Behalf Of Richard (Rick) Karlquist
Sent: Wednesday, January 30, 2013 6:17 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Low noise power supplies?


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies?

[David]

I have seen it used in a couple of Tektronix TM500 instruments but the
purpose may have been to generate a lower voltage power supply rail
instead of noise reduction.  Tektronix often added LC sections on
their switching power supply outputs and distributed smaller LC
sections to prevent coupling between different circuits.

On Thu, 31 Jan 2013 22:12:42 -0600, "Max Robinson"
 wrote:

>You haven't seen it used because it doesn't work very well.  It appeared in 
>a few pieces of Heathkit equipment but I don't think HP or Tek used it at 
>all.  Any AC component of base to collector voltage has a small but definite 
>effect on Vbe which transfers voltage in the reverse direction from 
>collector to emitter even though the base is held at AC ground.  A three 
>terminal regulator does a better job of suppressing ripple from a power 
>supply.
>
>Regulators use a zener diode as the reference and there are circuits in 
>which a zener is used as a noise source.  What does that tell you?  The 
>quietest power supply is an analog regulator followed by one or more RC 
>filter sections.  The inductor in an LC filter is likely to pick up more hum 
>and noise than it filters out.  My presumption is that a low noise power 
>supply is likely to be providing a small amount of power to the load and 
>load regulation is probably not a problem.
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Re: [time-nuts] Low noise power supplies?

[Max Robinson]

You haven't seen it used because it doesn't work very well.  It appeared in 
a few pieces of Heathkit equipment but I don't think HP or Tek used it at 
all.  Any AC component of base to collector voltage has a small but definite 
effect on Vbe which transfers voltage in the reverse direction from 
collector to emitter even though the base is held at AC ground.  A three 
terminal regulator does a better job of suppressing ripple from a power 
supply.


Regulators use a zener diode as the reference and there are circuits in 
which a zener is used as a noise source.  What does that tell you?  The 
quietest power supply is an analog regulator followed by one or more RC 
filter sections.  The inductor in an LC filter is likely to pick up more hum 
and noise than it filters out.  My presumption is that a low noise power 
supply is likely to be providing a small amount of power to the load and 
load regulation is probably not a problem.


Regards.

Max.  K 4 O DS.

Email: m...@maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
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- Original Message - 
From: "Joe Leikhim" 

To: 
Sent: Thursday, January 31, 2013 2:39 PM
Subject: [time-nuts] Low noise power supplies?


Back when I was in product engineering there was a VCO design that used a 
"superfilter" circuit. It consisted of a pass transistor and a filter cap 
from base to ground. The gain of the transistor multiplied the effective 
capacitance. I have not seen this configuration since.


--
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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Re: [time-nuts] Low noise power supplies?

[Richard (Rick) Karlquist]

One more thought: Many oscillators have internal regulators that are not
nearly as good as what you can build.  No sense using an external supply
with 5 nV per root Hz noise density if it will be re-regulated inside
the oscillator by a circuit that has a noise density of 250 nV per root Hz.

Best regards,

Charles


Good point.

Just to clarify my original request, my colleagues are currently using
batteries, and they don't have internal regulators.  Their problem is
not that the batteries don't work, but they want to travel around and
give demos and the batteries obviously are a PITA.

BTW, one of papers cited had a reference to Fred Walls paper on
battery noise.  Fred knocks it out the park as usual.  He was
like a rock star at FCS in those days.  A rare example of
government productivity.

Rick Karlquist N6RK
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[time-nuts] Low noise power supplies?

[Joe Leikhim]

Back when I was in product engineering there was a VCO design that used 
a "superfilter" circuit. It consisted of a pass transistor and a filter 
cap from base to ground. The gain of the transistor multiplied the 
effective capacitance. I have not seen this configuration since.


--
Joe Leikhim


Leikhim and Associates

Communications Consultants

Oviedo, Florida

jleik...@leikhim.com

407-982-0446

WWW.LEIKHIM.COM

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Re: [time-nuts] Low noise power supplies?

[Charles P. Steinmetz]

Bob wrote:

An AD 797, a couple of metal film resistors, and a fairly large (say 
47 uf) plastic cap work pretty well.


The band from 10 Hz down to 0.1 or 0.01 Hz is generally important 
when testing oscillators.  To keep the 797 input noise density below 
a few nV per root Hz, the terminations must have very low 
resistance.  With such low resistance, a 47 uF cap won't even get you 
to 10 Hz, much less 0.1 or 0.01 Hz.


One more thought: Many oscillators have internal regulators that are 
not nearly as good as what you can build.  No sense using an external 
supply with 5 nV per root Hz noise density if it will be re-regulated 
inside the oscillator by a circuit that has a noise density of 250 nV 
per root Hz.


Best regards,

Charles




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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

If you are driving a spectrum analyzer, the 10,000X mentioned in the app note 
simply is not needed. A gain of 10X or less will get you to below 2 nv / 
sqrt(Hz)  at 100 Hz and beyond. A 10 Hz blocking cap does not need to be a "24 
hours to stabilize" device.  An AD 797, a couple of metal film resistors, and a 
fairly large (say 47 uf) plastic cap work pretty well.

Bob

On Jan 31, 2013, at 7:20 PM, Charles P. Steinmetz 
 wrote:

> tvb wrote:
> 
>> I'll answer the question with anther question -- how does one properly 
>> measure power supply noise? Does it boil down to a single number, a couple 
>> of key numbers, or is it a plot, or several plots?
> 
> There are a number of "standard" ways, some of which have been mentioned by 
> others, none of which is all that helpful IMO.
> 
> What I find most useful is a plot of noise density vs. frequency from, say, 
> 0.1 Hz to as high as you require.  The data should be taken and processed 
> with sufficient frequency resolution to show any spurs in the band of 
> interest.  It is often helpful to have several plots, each covering part of 
> the band of interest, to improve the displayed resolution of spurs.
> 
> NOTE:  Designing a preamp for collecting the data is far from trivial.  
> Articles have been written about it (see, for example, Linear Technology 
> Application Note 124 by Jim Williams ).
> 
> Best regards,
> 
> Charles
> 
> 
> 
> 
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Re: [time-nuts] Low noise power supplies?

[SAIDJACK]

Or a good battery as a source for the regulators as discussed in this  
thread already.
 
It's quite nice to have all the different Voltages available at the same  
time, with up to 200mA.
 
bye,
Said
 
 
In a message dated 1/31/2013 13:12:33 Pacific Standard Time, li...@rtty.us  
writes:

Hi

For $393.75 does it come with a wall wart? 

If not  I would definitely go for a "medical" ground isolated / low leakage
version  to power the beast. The added cost over a plain jane wall wart 
won't
add  much to the purchase price percentage wise.

Bob

-Original  Message-
From: time-nuts-boun...@febo.com  [mailto:time-nuts-boun...@febo.com] On
Behalf Of saidj...@aol.com
Sent:  Thursday, January 31, 2013 3:58 PM
To: time-nuts@febo.com;  les...@veenstras.com
Subject: Re: [time-nuts] Low noise power  supplies?

Not sure if anyone posted this here yet, but Abracom has a  very low noise  
(7nV/RtHz at 1KHz) power source for VCO's etc, with  various outputs. It's 
sold  on DIgikey or Mouser I think.

Here  is a review of that  unit:

_http://jaunty-electronics.com/blog/category/reviews/_  
(http://jaunty-electronics.com/blog/category/reviews/)  

Co-incidentally he also has a review of one of our units on the  same  page.

This is a very handy and reasonably priced power  supply for many  
low-noise 
type of  experiments.

bye,
Said


In a message dated 1/30/2013  21:36:50 Pacific Standard Time,  
bruce.griffi...@xtra.co.nz  writes:

Lester  Veenstra wrote:
> The typical test supply on  a bench for clean VCO  testing is a small gel 
cell
>  battery.  For a regulated power  supply, make one using a 723. The  723 
has
> far lower noise out than the  monolithic  regulators.
>
>
Depends on the variety  of  723 some are noisier than others.
Some use an internal zener  reference,  some use a bandgap reference.
The original used a  zener  reference.

Bruce
> Lester B Veenstra  MØYCM  K1YCM  W8YCM
> les...@veenstras.com
>
> US Postal  Address:
>  5 Shrine Club Drive
> HC84 Box 89C
> Keyser  WV 26726
> GPS:  39.33675 N  78.9823527 W
>
>  Telephones:
> Home:+1-304-289-6057
> US cell   +1-304-790-9192
> UK cell   +44-(0)7849-248-749
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> Jamaica:   +1-876-456-8898
>   
>  This e-mail  and any documents attached hereto contain confidential or
>   privileged information. The information is intended to be for use only  
 
by
> the individual or entity to whom they are addressed. If you are  not  the
> intended recipient or the person responsible for  delivering the  e-mail 
to
> the intended recipient, be aware that  any disclosure,  copying, 
distribution
> or use of the contents  of this e-mail or any  documents attached hereto 
is
>   prohibited.
>
>
>
> -Original  Message-
>  From: time-nuts-boun...@febo.com  [mailto:time-nuts-boun...@febo.com]  On
> Behalf Of Richard (Rick)  Karlquist
> Sent: Wednesday, January  30, 2013 9:17 PM
> To:  Discussion of precise time and frequency  measurement
> Subject:  [time-nuts] Low noise power  supplies?
>
>
> I know  this topic has been discussed in the  past on the list, but a
>  colleague is asking if there are any off the  shelf low noise power  
supplies
> for testing oscillators.   Something a cut  above an HP "brick" lab power
> supply etc.  They  are hoping  to avoid having to homebrew a power
> conditioning   circuit.
> Did we ever arrive at a concensus as to the state of the  art  in homebrew
> power conditioning circuits?
>
> Any  help  would be appreciated.
>
> Rick Karlquist  N6RK
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Re: [time-nuts] Low noise power supplies?

[Adrian]

Charles,

thanks for posting. That is the LTC application note I had in mind.

And here is Bruce's contribution to low noise PS design and measurement:

http://www.ko4bb.com/~bruce/LowNoisePowerSupplies.html

Don't miss to scroll fully down. There is a link to an IEEE paper 
discussing chemical battery noise measurement.


Adrian


Charles P. Steinmetz schrieb:

tvb wrote:

I'll answer the question with anther question -- how does one 
properly measure power supply noise? Does it boil down to a single 
number, a couple of key numbers, or is it a plot, or several plots?


There are a number of "standard" ways, some of which have been 
mentioned by others, none of which is all that helpful IMO.


What I find most useful is a plot of noise density vs. frequency from, 
say, 0.1 Hz to as high as you require.  The data should be taken and 
processed with sufficient frequency resolution to show any spurs in 
the band of interest.  It is often helpful to have several plots, each 
covering part of the band of interest, to improve the displayed 
resolution of spurs.


NOTE:  Designing a preamp for collecting the data is far from 
trivial.  Articles have been written about it (see, for example, 
Linear Technology Application Note 124 by Jim Williams 
).


Best regards,

Charles




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Re: [time-nuts] Low noise power supplies?

[Charles P. Steinmetz]

tvb wrote:

I'll answer the question with anther question -- how does one 
properly measure power supply noise? Does it boil down to a single 
number, a couple of key numbers, or is it a plot, or several plots?


There are a number of "standard" ways, some of which have been 
mentioned by others, none of which is all that helpful IMO.


What I find most useful is a plot of noise density vs. frequency 
from, say, 0.1 Hz to as high as you require.  The data should be 
taken and processed with sufficient frequency resolution to show any 
spurs in the band of interest.  It is often helpful to have several 
plots, each covering part of the band of interest, to improve the 
displayed resolution of spurs.


NOTE:  Designing a preamp for collecting the data is far from 
trivial.  Articles have been written about it (see, for example, 
Linear Technology Application Note 124 by Jim Williams 
).


Best regards,

Charles




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Re: [time-nuts] Low noise power supplies?

[Poul-Henning Kamp]

Content-Type: text/plain; charset=ISO-8859-1

In message , "Tom Van Baak" writes:

>We have rigorous ways to compare and report oscillator performance;
>both as numbers and as plots. Is there something equivalent for
>power supplies?

Phase Noise measured on a 0Hz carrier ?

If you want the dynamic behaviour, it gets much more tricky, because
then you have both the spectrum of the load-changes and the
supply-changes, resulting in a spectrum output from the PSU.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Low noise power supplies?

[Adrian]

There are at least two methods.

First, the broadband or time domain method that uses a low noise 
amplifier and oscilloscope, and specifies noise voltage within a certain 
bandwidth. For details check application notes from LTC and Analog Devices.


The narrowband or frequency domain method specifies noise voltage within 
a normalized bandwidth (nV/sqrt(Hz)) at a specific frequency.
A typical test setup is included in the HP 3048A phase noise measurement 
system as so-called base-band noise measurement. For higher noise 
voltages, the 3561A dynamic signal analyzer alone is used with a DC 
blocking capacitor. For lower noise voltages, the signal is first 
amplified by the LNA that is part of the 11848A phase noise test set. 
For details please see the HP 3048A manual that can be downloaded from 
http://www.hparchive.com/hp_equipment.htm
Note the Opt K23 DC blocking filter. There is an insertion loss of 6 dB 
to be entered in the 3048A software when using the DC block in 
conjunction with the 11848A.
Obviously, any FFT analyzer plus LNA and coupling cap can be used for 
that method. The major advantage of the 3048A system is the automatic 
generation of plots.


Adrian

John Ackermann N8UR schrieb:
And this (very interesting) thread brings up the question of 
measurement methods.  Some time ago I searched around and didn't find 
much on a standard way to measure noise on low voltage DC supplies.


John


On 1/31/2013 11:36 AM, Bob Camp wrote:

Hi

I think the comparison of PSD on a power supply to phase noise and phase
noise plots is a pretty good one in this case.

For most applications nV/sqrt(Hz) is a pretty good way to check 
things out
on a supply or regulator. It's not quite the same thing as dbc / 
sqrt(Hz)

but it conveys the same sort of information. Unless you have a *very*
sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be "a 
very quiet
supply". The main limit you hit is in the sub 100 Hz region where you 
likely

see things like popcorn noise.

AC ripple is no different than spurs in phase noise testing. You 
sometimes
see people who ignore them when plotting phase noise. I'd suggest 
that they

are an important part of characterizing a power supply.

As with phase noise, frequency ranges are going to be application 
dependant.
I may not care about 0.1 to 10 Hz phase noise for project A. It may 
be the

only thing I care about for project B. Same thing with power supplies.

With a good enough voltmeter you could carry the analogy one step 
further

and compute an ADEV like number on the output voltage. I suspect that's
carrying things a bit far.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Tom Van Baak
Sent: Thursday, January 31, 2013 9:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low noise power supplies?

Hi Rick,

I'll answer the question with anther question -- how does one properly
measure power supply noise? Does it boil down to a single number, a 
couple

of key numbers, or is it a plot, or several plots?

I ask because without some sort of standard test and reporting method it
just becomes a word game. Like, "use batteries because they are better";
"use my design because it is quiet"; "this has lower noise than 
that". RMS
AC ripple or nV/rtHz sounds like a good start, but I'm wondering if 
there's

something more complete.

I was never quite satisfied with the outcome of comparing a half 
dozen power

supplies this way:
http://www.leapsecond.com/pages/tbolt/noise.htm

We have rigorous ways to compare and report oscillator performance; 
both as

numbers and as plots. Is there something equivalent for power supplies?

Thanks,
/tvb


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK



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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

For $393.75 does it come with a wall wart? 

If not I would definitely go for a "medical" ground isolated / low leakage
version to power the beast. The added cost over a plain jane wall wart won't
add much to the purchase price percentage wise.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of saidj...@aol.com
Sent: Thursday, January 31, 2013 3:58 PM
To: time-nuts@febo.com; les...@veenstras.com
Subject: Re: [time-nuts] Low noise power supplies?

Not sure if anyone posted this here yet, but Abracom has a very low noise  
(7nV/RtHz at 1KHz) power source for VCO's etc, with various outputs. It's 
sold  on DIgikey or Mouser I think.

Here is a review of that unit:
 
_http://jaunty-electronics.com/blog/category/reviews/_ 
(http://jaunty-electronics.com/blog/category/reviews/) 
 
Co-incidentally he also has a review of one of our units on the same  page.
 
This is a very handy and reasonably priced power supply for many  low-noise 
type of experiments.
 
bye,
Said
 
 
In a message dated 1/30/2013 21:36:50 Pacific Standard Time,  
bruce.griffi...@xtra.co.nz writes:

Lester  Veenstra wrote:
> The typical test supply on a bench for clean VCO  testing is a small gel 
cell
> battery.  For a regulated power  supply, make one using a 723. The 723 has
> far lower noise out than the  monolithic regulators.
>
>
Depends on the variety  of 723 some are noisier than others.
Some use an internal zener reference,  some use a bandgap reference.
The original used a zener  reference.

Bruce
> Lester B Veenstra  MØYCM K1YCM  W8YCM
> les...@veenstras.com
>
> US Postal Address:
>  5 Shrine Club Drive
> HC84 Box 89C
> Keyser WV 26726
> GPS:  39.33675 N  78.9823527 W
>
> Telephones:
> Home:+1-304-289-6057
> US cell +1-304-790-9192
> UK cell  +44-(0)7849-248-749
> Guam Cell:   +1-671-929-8141
> Jamaica: +1-876-456-8898
>   
>  This e-mail and any documents attached hereto contain confidential or
>  privileged information. The information is intended to be for use only  
by
> the individual or entity to whom they are addressed. If you are not  the
> intended recipient or the person responsible for delivering the  e-mail to
> the intended recipient, be aware that any disclosure,  copying, 
distribution
> or use of the contents of this e-mail or any  documents attached hereto is
>  prohibited.
>
>
>
> -Original Message-
>  From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]  On
> Behalf Of Richard (Rick) Karlquist
> Sent: Wednesday, January  30, 2013 9:17 PM
> To: Discussion of precise time and frequency  measurement
> Subject: [time-nuts] Low noise power  supplies?
>
>
> I know this topic has been discussed in the  past on the list, but a
> colleague is asking if there are any off the  shelf low noise power 
supplies
> for testing oscillators.   Something a cut above an HP "brick" lab power
> supply etc.  They  are hoping to avoid having to homebrew a power
> conditioning  circuit.
> Did we ever arrive at a concensus as to the state of the art  in homebrew
> power conditioning circuits?
>
> Any help  would be appreciated.
>
> Rick Karlquist N6RK
>  ___
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Re: [time-nuts] Low noise power supplies?

[SAIDJACK]

Not sure if anyone posted this here yet, but Abracom has a very low noise  
(7nV/RtHz at 1KHz) power source for VCO's etc, with various outputs. It's 
sold  on DIgikey or Mouser I think.

Here is a review of that unit:
 
_http://jaunty-electronics.com/blog/category/reviews/_ 
(http://jaunty-electronics.com/blog/category/reviews/) 
 
Co-incidentally he also has a review of one of our units on the same  page.
 
This is a very handy and reasonably priced power supply for many  low-noise 
type of experiments.
 
bye,
Said
 
 
In a message dated 1/30/2013 21:36:50 Pacific Standard Time,  
bruce.griffi...@xtra.co.nz writes:

Lester  Veenstra wrote:
> The typical test supply on a bench for clean VCO  testing is a small gel 
cell
> battery.  For a regulated power  supply, make one using a 723. The 723 has
> far lower noise out than the  monolithic regulators.
>
>
Depends on the variety  of 723 some are noisier than others.
Some use an internal zener reference,  some use a bandgap reference.
The original used a zener  reference.

Bruce
> Lester B Veenstra  MØYCM K1YCM  W8YCM
> les...@veenstras.com
>
> US Postal Address:
>  5 Shrine Club Drive
> HC84 Box 89C
> Keyser WV 26726
> GPS:  39.33675 N  78.9823527 W
>
> Telephones:
> Home:+1-304-289-6057
> US cell +1-304-790-9192
> UK cell  +44-(0)7849-248-749
> Guam Cell:   +1-671-929-8141
> Jamaica: +1-876-456-8898
>   
>  This e-mail and any documents attached hereto contain confidential or
>  privileged information. The information is intended to be for use only  
by
> the individual or entity to whom they are addressed. If you are not  the
> intended recipient or the person responsible for delivering the  e-mail to
> the intended recipient, be aware that any disclosure,  copying, 
distribution
> or use of the contents of this e-mail or any  documents attached hereto is
>  prohibited.
>
>
>
> -Original Message-
>  From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]  On
> Behalf Of Richard (Rick) Karlquist
> Sent: Wednesday, January  30, 2013 9:17 PM
> To: Discussion of precise time and frequency  measurement
> Subject: [time-nuts] Low noise power  supplies?
>
>
> I know this topic has been discussed in the  past on the list, but a
> colleague is asking if there are any off the  shelf low noise power 
supplies
> for testing oscillators.   Something a cut above an HP "brick" lab power
> supply etc.  They  are hoping to avoid having to homebrew a power
> conditioning  circuit.
> Did we ever arrive at a concensus as to the state of the art  in homebrew
> power conditioning circuits?
>
> Any help  would be appreciated.
>
> Rick Karlquist N6RK
>  ___
> time-nuts mailing list  -- time-nuts@febo.com To unsubscribe, go to
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[time-nuts] Low noise power supplies?

[Burt I. Weiner]

Bob,

I have a pair of HP-3551A's*.  I'm very familiar with making 
transmission lines measurements, and it seems that measuring power 
supply noise would be the same, except that you want to block the DC 
from the input of the instrument.  What has your procedure been and 
what numbers have you come up with?  Since these instruments read in 
dBm0, do you reference from the supply's voltage and then convert to 
mV (difference)?


* One that I picked up off eBay for $75.00 looks new and came with 
the complete manual, and the battery will run it most of the day.


Thanks,

Burt, K6OQK



Subject: Re: [time-nuts] Low noise power supplies?

A non-standard but repeatable way to measure power supply noise is 
to use a Transmission Impairment Measuring Set (TIMS) such as the 
HP3945(6)A or 3551
(2)A. These were intended for use in pairs to assess analog 
telephone lines for data use. As well as an AF generator, frequency 
counter, amplifier, monitor speaker and level meter they will 
measure broadband noise. Being designed for POTS they will also 
withstand at least 50V DC at the input while measuring the noise. 
You can also apply internal filters if required. The last digit 
designates a North American? (BELL) or European (CCITT) standard 
unit, but broadband noise is the same. They can be picked up really 
cheaply now (list was$3000-$5000) and make a nice compact audio test set.


Robert G8RPI.





Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 


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Re: [time-nuts] Low noise power supplies?

[Robert Atkinson]

Oops,
 that should be HP4945(6)A not 3945


Robert.



 From: Robert Atkinson 
To: Discussion of precise time and frequency measurement  
Sent: Thursday, 31 January 2013, 18:46
Subject: Re: [time-nuts] Low noise power supplies?
 
A non-standard but repeatable way to measure power supply noise is to use a 
Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551
(2)A. These were intended for use in pairs to assess analog telephone lines for 
data use. As well as an AF generator, frequency counter, amplifier, monitor 
speaker and level meter they will measure broadband noise. Being designed for 
POTS they will also withstand at least 50V DC at the input while measuring the 
noise. You can also apply internal filters if required. The last digit 
designates a North American  (BELL) or European (CCITT) standard unit, but 
broadband noise is the same. They can be picked up really cheaply now (list 
was$3000-$5000) and make a nice compact audio test set.

Robert G8RPI.





From: Bob Camp 
To: 'Discussion of precise time and frequency measurement'  
Sent: Thursday, 31 January 2013, 18:02
Subject: Re: [time-nuts] Low noise power supplies?

Hi

A very common way to check one is to use the HP 3561 off of the old 3048
phase noise test set. With a simple op amp based preamp you can easily get
down below 3 nv / sqrt(Hz). With more exotic amps you can get well below
that. 

Volts over a bandwidth really don't tell the story very well. In the popcorn
noise region, you don't have much choice. Once you get past that PSD is very
much the right way to go. 

For some numbers once you are out of the popcorn / flicker noise region:

1 nV / sqrt(Hz) = about as quiet as it's worth getting ever.
10 nV / sqrt(Hz) = good enough for anything you are likely to be doing
100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases
1uV / sqrt(Hz) = pretty awful.  

As always, it really depends on what you are doing. A microprocessor will
not be bothered much at all by a relatively noisy supply. 

Bob 

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Burt I. Weiner
Sent: Thursday, January 31, 2013 12:08 PM
To: time-nuts@febo.com
Subject: [time-nuts] Low noise power supplies?

Gang,

I'm following this thread with great interest, but, just for my own 
reference, what is considered low power supply noise?  Can you give 
me some numbers and over what bandwidth?

Thanks,

Burt, K6OQK



>         
>Subject: Re: [time-nuts] Low noise power supplies?
>
>
>Hi
>
>To answer the original question - Power Design makes some pretty quiet
bench
>supplies. If you are doing low noise testing, batteries often will let you
>get rid of one more ground loop. Even well built power supplies are not as
>well line isolated as a battery.
>
>Bob

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK

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Re: [time-nuts] Low noise power supplies?

[Robert Atkinson]

A non-standard but repeatable way to measure power supply noise is to use a 
Transmission Impairment Measuring Set (TIMS) such as the HP3945(6)A or 3551
(2)A. These were intended for use in pairs to assess analog telephone lines for 
data use. As well as an AF generator, frequency counter, amplifier, monitor 
speaker and level meter they will measure broadband noise. Being designed for 
POTS they will also withstand at least 50V DC at the input while measuring the 
noise. You can also apply internal filters if required. The last digit 
designates a North American  (BELL) or European (CCITT) standard unit, but 
broadband noise is the same. They can be picked up really cheaply now (list 
was$3000-$5000) and make a nice compact audio test set.

Robert G8RPI.





 From: Bob Camp 
To: 'Discussion of precise time and frequency measurement'  
Sent: Thursday, 31 January 2013, 18:02
Subject: Re: [time-nuts] Low noise power supplies?
 
Hi

A very common way to check one is to use the HP 3561 off of the old 3048
phase noise test set. With a simple op amp based preamp you can easily get
down below 3 nv / sqrt(Hz). With more exotic amps you can get well below
that. 

Volts over a bandwidth really don't tell the story very well. In the popcorn
noise region, you don't have much choice. Once you get past that PSD is very
much the right way to go. 

For some numbers once you are out of the popcorn / flicker noise region:

1 nV / sqrt(Hz) = about as quiet as it's worth getting ever.
10 nV / sqrt(Hz) = good enough for anything you are likely to be doing
100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases
1uV / sqrt(Hz) = pretty awful.  

As always, it really depends on what you are doing. A microprocessor will
not be bothered much at all by a relatively noisy supply. 

Bob 

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Burt I. Weiner
Sent: Thursday, January 31, 2013 12:08 PM
To: time-nuts@febo.com
Subject: [time-nuts] Low noise power supplies?

Gang,

I'm following this thread with great interest, but, just for my own 
reference, what is considered low power supply noise?  Can you give 
me some numbers and over what bandwidth?

Thanks,

Burt, K6OQK



>         
>Subject: Re: [time-nuts] Low noise power supplies?
>
>
>Hi
>
>To answer the original question - Power Design makes some pretty quiet
bench
>supplies. If you are doing low noise testing, batteries often will let you
>get rid of one more ground loop. Even well built power supplies are not as
>well line isolated as a battery.
>
>Bob

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK

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Re: [time-nuts] Low noise power supplies?

[David Kirkby]

On 31 January 2013 17:11, John Ackermann N8UR  wrote:
> And this (very interesting) thread brings up the question of measurement
> methods.  Some time ago I searched around and didn't find much on a standard
> way to measure noise on low voltage DC supplies.
>
> John

Did you try the volt-nuts mailing list?

Dave
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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

A very common way to check one is to use the HP 3561 off of the old 3048
phase noise test set. With a simple op amp based preamp you can easily get
down below 3 nv / sqrt(Hz). With more exotic amps you can get well below
that. 

Volts over a bandwidth really don't tell the story very well. In the popcorn
noise region, you don't have much choice. Once you get past that PSD is very
much the right way to go. 

For some numbers once you are out of the popcorn / flicker noise region:

1 nV / sqrt(Hz) = about as quiet as it's worth getting ever.
10 nV / sqrt(Hz) = good enough for anything you are likely to be doing
100 nV / sqrt(Hz) = noisy enough to begin to bother you in some cases
1uV / sqrt(Hz) = pretty awful.   

As always, it really depends on what you are doing. A microprocessor will
not be bothered much at all by a relatively noisy supply. 

Bob 

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Burt I. Weiner
Sent: Thursday, January 31, 2013 12:08 PM
To: time-nuts@febo.com
Subject: [time-nuts] Low noise power supplies?

Gang,

I'm following this thread with great interest, but, just for my own 
reference, what is considered low power supply noise?  Can you give 
me some numbers and over what bandwidth?

Thanks,

Burt, K6OQK



>     
>Subject: Re: [time-nuts] Low noise power supplies?
>
>
>Hi
>
>To answer the original question - Power Design makes some pretty quiet
bench
>supplies. If you are doing low noise testing, batteries often will let you
>get rid of one more ground loop. Even well built power supplies are not as
>well line isolated as a battery.
>
>Bob

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 

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Re: [time-nuts] Low noise power supplies?

[gcarlistaa]

On 31.01.2013 09:05, Adrian wrote:

Rick,

the E3610A is really clean.



The discussion is interesting, but the original question did ask about 
off the shelf so I have been watching for any mention of HP/Agilent 
precision power supplies.  The E3610A specification says 200 uVrms, 2mv 
pp ripple and noise over the range 20Hz to 20 MHz.  The now obsolete 
HP6114A spec is much better at 40uVrms, 100uV pp up to 20MHz.  The 6114A 
is no longer available (except on eBay), but there should be something 
equivalent or better.


I discovered the 6114A one day when I needed a nice stable voltage 
source to check some data acquisition equipment.  My first pick was a 
gel-cel,  but with a 34401 DMM you can watch those self-discharge.  A 
regular bench supply kind of wanders around.  But after a few minute 
warm-up the 6114A that I found sitting on a storage shelf was nice and 
stable.  I mentioned the specification for noise because I have observed 
its stability, but have not made any measurements on its noise.



Gary

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Re: [time-nuts] Low noise power supplies?

[John Ackermann N8UR]

And this (very interesting) thread brings up the question of measurement 
methods.  Some time ago I searched around and didn't find much on a 
standard way to measure noise on low voltage DC supplies.


John


On 1/31/2013 11:36 AM, Bob Camp wrote:

Hi

I think the comparison of PSD on a power supply to phase noise and phase
noise plots is a pretty good one in this case.

For most applications nV/sqrt(Hz) is a pretty good way to check things out
on a supply or regulator. It's not quite the same thing as dbc / sqrt(Hz)
but it conveys the same sort of information. Unless you have a *very*
sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be "a very quiet
supply". The main limit you hit is in the sub 100 Hz region where you likely
see things like popcorn noise.

AC ripple is no different than spurs in phase noise testing. You sometimes
see people who ignore them when plotting phase noise. I'd suggest that they
are an important part of characterizing a power supply.

As with phase noise, frequency ranges are going to be application dependant.
I may not care about 0.1 to 10 Hz phase noise for project A. It may be the
only thing I care about for project B. Same thing with power supplies.

With a good enough voltmeter you could carry the analogy one step further
and compute an ADEV like number on the output voltage. I suspect that's
carrying things a bit far.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Tom Van Baak
Sent: Thursday, January 31, 2013 9:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low noise power supplies?

Hi Rick,

I'll answer the question with anther question -- how does one properly
measure power supply noise? Does it boil down to a single number, a couple
of key numbers, or is it a plot, or several plots?

I ask because without some sort of standard test and reporting method it
just becomes a word game. Like, "use batteries because they are better";
"use my design because it is quiet"; "this has lower noise than that". RMS
AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's
something more complete.

I was never quite satisfied with the outcome of comparing a half dozen power
supplies this way:
http://www.leapsecond.com/pages/tbolt/noise.htm

We have rigorous ways to compare and report oscillator performance; both as
numbers and as plots. Is there something equivalent for power supplies?

Thanks,
/tvb


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK



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[time-nuts] Low noise power supplies?

[Burt I. Weiner]

Gang,

I'm following this thread with great interest, but, just for my own 
reference, what is considered low power supply noise?  Can you give 
me some numbers and over what bandwidth?


Thanks,

Burt, K6OQK





Subject: Re: [time-nuts] Low noise power supplies?


Hi

To answer the original question - Power Design makes some pretty quiet bench
supplies. If you are doing low noise testing, batteries often will let you
get rid of one more ground loop. Even well built power supplies are not as
well line isolated as a battery.

Bob


Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
b...@att.net
www.biwa.cc
K6OQK 


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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

I think the comparison of PSD on a power supply to phase noise and phase
noise plots is a pretty good one in this case. 

For most applications nV/sqrt(Hz) is a pretty good way to check things out
on a supply or regulator. It's not quite the same thing as dbc / sqrt(Hz)
but it conveys the same sort of information. Unless you have a *very*
sensitive part, anything below 10 nV/ sqrt(Hz) is likely to be "a very quiet
supply". The main limit you hit is in the sub 100 Hz region where you likely
see things like popcorn noise. 

AC ripple is no different than spurs in phase noise testing. You sometimes
see people who ignore them when plotting phase noise. I'd suggest that they
are an important part of characterizing a power supply. 

As with phase noise, frequency ranges are going to be application dependant.
I may not care about 0.1 to 10 Hz phase noise for project A. It may be the
only thing I care about for project B. Same thing with power supplies. 

With a good enough voltmeter you could carry the analogy one step further
and compute an ADEV like number on the output voltage. I suspect that's
carrying things a bit far.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Tom Van Baak
Sent: Thursday, January 31, 2013 9:43 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low noise power supplies?

Hi Rick,

I'll answer the question with anther question -- how does one properly
measure power supply noise? Does it boil down to a single number, a couple
of key numbers, or is it a plot, or several plots?

I ask because without some sort of standard test and reporting method it
just becomes a word game. Like, "use batteries because they are better";
"use my design because it is quiet"; "this has lower noise than that". RMS
AC ripple or nV/rtHz sounds like a good start, but I'm wondering if there's
something more complete.

I was never quite satisfied with the outcome of comparing a half dozen power
supplies this way:
http://www.leapsecond.com/pages/tbolt/noise.htm

We have rigorous ways to compare and report oscillator performance; both as
numbers and as plots. Is there something equivalent for power supplies?

Thanks,
/tvb

> I know this topic has been discussed in the past on the list, but
> a colleague is asking if there are any off the shelf low
> noise power supplies for testing oscillators.  Something
> a cut above an HP "brick" lab power supply etc.  They are hoping
> to avoid having to homebrew a power conditioning circuit.
> Did we ever arrive at a concensus as to the state of the art
> in homebrew power conditioning circuits?
> 
> Any help would be appreciated.
> 
> Rick Karlquist N6RK


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Re: [time-nuts] Low noise power supplies?

[David Kirkby]

On 31 January 2013 04:28, Chris Albertson  wrote:
> On Wed, Jan 30, 2013 at 6:16 PM, Richard (Rick) Karlquist
>  wrote:
>>
>> I know this topic has been discussed in the past on the list, but
>> a colleague is asking if there are any off the shelf low
>> noise power supplies for testing oscillators.  Something
>> a cut above an HP "brick" lab power supply etc.
>
> For once the "best" is also cheap:  Batteries.

My first thought was that a battery was best. Obviously batteries will
have a long term drop in voltage as the battery gets more depleted,
but is there any short term noise from a battery? There is going to be
thermal noise, but I wonder if some types of batteries are better from
a noise perspective than others?

Perhaps a number of batteries having the same nomilal voltage,
capacity and internal resistance are all equal, but perhaps some are
more equal than others!


Dave

Dave
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Re: [time-nuts] Low noise power supplies?

[Tom Van Baak]

Hi Rick,

I'll answer the question with anther question -- how does one properly measure 
power supply noise? Does it boil down to a single number, a couple of key 
numbers, or is it a plot, or several plots?

I ask because without some sort of standard test and reporting method it just 
becomes a word game. Like, "use batteries because they are better";  "use my 
design because it is quiet"; "this has lower noise than that". RMS AC ripple or 
nV/rtHz sounds like a good start, but I'm wondering if there's something more 
complete.

I was never quite satisfied with the outcome of comparing a half dozen power 
supplies this way:
http://www.leapsecond.com/pages/tbolt/noise.htm

We have rigorous ways to compare and report oscillator performance; both as 
numbers and as plots. Is there something equivalent for power supplies?

Thanks,
/tvb

> I know this topic has been discussed in the past on the list, but
> a colleague is asking if there are any off the shelf low
> noise power supplies for testing oscillators.  Something
> a cut above an HP "brick" lab power supply etc.  They are hoping
> to avoid having to homebrew a power conditioning circuit.
> Did we ever arrive at a concensus as to the state of the art
> in homebrew power conditioning circuits?
> 
> Any help would be appreciated.
> 
> Rick Karlquist N6RK


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Re: [time-nuts] Low noise power supplies?

[Adrian]

Rick,

the E3610A is really clean.

If that isn't good enough, there are some audio-related circuits like 
the ALWSR.

http://www.andrewweekes.talktalk.net/Manuals/ALWSR_rev2.9_Iss005s.pdf
It's based on a Walt Jung design (Analog Devices).

Here's the man himself with tons of valuable information about ultra low 
PS design:

http://waltjung.org/Library.html

Adrian


Richard (Rick) Karlquist schrieb:


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies?

[Garry Thorp]

If the main concern is about low-frequency noise the LT1763 might be worth 
considering for a simple solution, as it is capable of lower noise than the 
data sheet shows. With a bypass capacitor (Cbyp) fitted, the noise floor is 
~30nV/rtHz. Although the data sheet only recommends up to 10nF for Cbyp, higher 
values continue to reduce the low-frequency noise. Correspondence with Linear 
Tech confirmed that it is OK to increase Cbyp as long as its leakage current is 
low enough and the output shunt capacitance is large enough.

With Cbyp=22uF and metal film resistors used, the noise at 1Hz (with +10.6V 
output) came down to not much above 30nV/rtHz. The downside is that the output 
voltage rise time is a few minutes! (And if you short the output, it takes just 
as long for it to come back again.) Maybe not a problem for lab use.

The LT1763 produces a noise peak around 150-200kHz if Cbyp is fitted (any 
value), but increasing the output capacitor to 100uF brings the peak down to 
~30nV/rtHz.

Garry Thorp
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Re: [time-nuts] Low noise power supplies?

[Bob Camp]

Hi

To answer the original question - Power Design makes some pretty quiet bench
supplies. If you are doing low noise testing, batteries often will let you
get rid of one more ground loop. Even well built power supplies are not as
well line isolated as a battery.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Charles P. Steinmetz
Sent: Thursday, January 31, 2013 5:33 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low noise power supplies?

Lester wrote:

>For a regulated power supply, make one using a 723. The 723 has
>far lower noise out than the monolithic regulators.

If you are willing to design your own regulator using a 723, you may 
as well use a few more parts to get a much better result.  Neither 
the internal reference nor the internal error amp in a 723 is 
anywhere near state of the art today with respect to noise, tempco, 
or speed.  Using readily available buried zener references and 
low-noise, high-speed op amps (or even a few discrete transistors), 
you can do several orders of magnitude better than a 723 in all 
respects.  The web is overflowing with designs (though not all of the 
circuits you find perform as advertised, so evaluate them with a 
critical eye and use your own sound judgment).

But wasn't the original question what is available off-the-shelf?

Best regards,

Charles




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Re: [time-nuts] Low noise power supplies?

[Gerhard Hoffmann]

Am 31.01.2013 05:28, schrieb Chris Albertson:

For once the "best" is also cheap:  Batteries.

But not all batteries are the same.  You want one with low internal
resistance, so a lead acid flooded battery will be the best.


Fred Walls & Co have done tests on batteries. The article is
somewhere on the NIST time/freq server.

regards, Gerhard
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Re: [time-nuts] Low noise power supplies?

[Gerhard Hoffmann]

Am 31.01.2013 03:16, schrieb Richard (Rick) Karlquist:


I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something


The E5052B signal source analyzer has low noise power
and control voltage supplies for just that purpose.

E5052 are not that exotic any more. At a customer's
I have seen 5 of them being sent on one day for calibration
and that did not create any bottleneck. :-)

regards, Gerhard

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Re: [time-nuts] Low noise power supplies?

[Charles P. Steinmetz]

Lester wrote:


For a regulated power supply, make one using a 723. The 723 has
far lower noise out than the monolithic regulators.


If you are willing to design your own regulator using a 723, you may 
as well use a few more parts to get a much better result.  Neither 
the internal reference nor the internal error amp in a 723 is 
anywhere near state of the art today with respect to noise, tempco, 
or speed.  Using readily available buried zener references and 
low-noise, high-speed op amps (or even a few discrete transistors), 
you can do several orders of magnitude better than a 723 in all 
respects.  The web is overflowing with designs (though not all of the 
circuits you find perform as advertised, so evaluate them with a 
critical eye and use your own sound judgment).


But wasn't the original question what is available off-the-shelf?

Best regards,

Charles




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Re: [time-nuts] Low noise power supplies?

[David C. Partridge]

PTAT == Proportional To Absolute Temperature 

Dave

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Re: [time-nuts] Low noise power supplies?

[Rex]

On 1/31/2013 12:20 AM, Bruce Griffiths wrote:
With some care its possible to make the emitter current of the shunt 
transistor approximately PTAT so that, at least for small signals the 
temperature dependence of the rejection is reduced significantly.


Sorry, what does PTAT mean? I'm not familiar with that term.



Its also possible to build a feedback style shunt regulator that has 
considerably higher supply rejection than the Wenzel circuit using an 
opamp and a shunt transistor together with a small resistance in 
series with one of the supply leads.


Bruce


The Wenzel article gives three circuit topologies. The third shows an 
opamp feeding a 2N4401 across 0.05 ohm in the power path. Sounds like 
what you are describing. Did you miss that one or are you describing 
something different?


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Re: [time-nuts] Low noise power supplies?

[Bruce Griffiths]

Poul-Henning Kamp wrote:

Content-Type: text/plain; charset=ISO-8859-1

In message, Tom Knox writes:
   

Starting with a hp supply this finesse regulator will really clean
up the output. http://www.wenzel.com/documents/finesse.html
 

I've played with that, and it can do impressive things.

However, to big caveats:

1.  It's very temperature sensitive so on average you only get tens
 of dB, not hundred dB damping.

2.  Noise which comes in from the load gets amplified.


   
With some care its possible to make the emitter current of the shunt 
transistor approximately PTAT so that, at least for small signals the 
temperature dependence of the rejection is reduced significantly.


Its also possible to build a feedback style shunt regulator that has 
considerably higher supply rejection than the Wenzel circuit using an 
opamp and a shunt transistor together with a small resistance in series 
with one of the supply leads.


Bruce
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Re: [time-nuts] Low noise power supplies?

[gary]

I've measured AA nicad impedance at a few kHz, but it was years ago. My 
recollection is it was in tens of milliohms.


ESR does have a frequency dependency. In the same time frame, I was 
trying to find a simple non-instrusive way to detect alkaline cells 
versus nicads. The key was in impedance versus frequency curve. It 
looked more than a bit hair brained, and given that there are no 
consumer devices that do automatic detection today, I gather no one else 
found an elegant solution.


But low ESR may not translate to low noise. Yeah, I know everyone is 
thinking thermal noise, but a battery is a chemical device. You can 
detect gas bubbles from electrical artifacts in some types of batteries. 
At least under high discharge. Also the impedance of nicads increases 
when they get old. I spent a ridiculous amount of time dealing with a 
customer that found some old batteries that were not being detected by 
the safety scheme built into a particular chip.


Lastly, the chemistry in these batteries isn't constant. Once you have 
one battery technology nailed down, they increase the capacity and it is 
a new ballgame. That lead to "chemistry independent" charging schemes 
where the chargers had uP interface so that the charging could be 
tweaked by the customer.


Personally, if the device you are using needs a power supply from god, 
it wasn't designed well. The manufacturer should incorporate the 
required regulation in the product so that it meets spec with run of the 
mill supplies. Nobody likes to spend time debugging some customer 
complaint due to a component outside your product.



On 1/30/2013 9:44 PM, Arthur Dent wrote:

But the only NiCd I know about are the AA sized ones.


I have some of the wet NiCd batteries that are capable of
putting out 200A continuously. I'm assuming the internal
resistance is pretty low. ;-)

Arthur
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Re: [time-nuts] Low noise power supplies?

[Poul-Henning Kamp]

Content-Type: text/plain; charset=ISO-8859-1

In message , Tom Knox writes:
>
>Starting with a hp supply this finesse regulator will really clean
>up the output. http://www.wenzel.com/documents/finesse.html

I've played with that, and it can do impressive things.

However, to big caveats:

1.  It's very temperature sensitive so on average you only get tens
of dB, not hundred dB damping.

2.  Noise which comes in from the load gets amplified.


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Low noise power supplies?

[Poul-Henning Kamp]

Content-Type: text/plain; charset=ISO-8859-1

In message , Mark Sims writes:
>
>A123 20Ah LiFePO4 cells have an internal resistance in the milliohm
>range.  Their M1 26650 format cells are around 8 milliohms.  Most
>high capacity (>3000 mAh) 18650 style lithium cells are around 10-15
>milliohms.

different chemistries have different levels of noise, and I belive
Lithium is not in the good end of the spectrum there.

As I understood the general theory: batteries have more noise the
further the electrodes are from being pure metals, so maybe the
best and lowest noise is to build a volta-pile ?


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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[time-nuts] Low noise power supplies?

[M. Simon]

Rick,

I'm just finishing up some low noise supplies that use the TPSA49xx regulator. 
The AC input is a 12 AC wall wart and it uses zener/darlington pre-regulators. 
+5 and +3.3 V @ 150 ma each. I have the boards in hand and am ordering parts. 
The voltages are tweakable. i.e. 5.1V and 3.4V for instance. 


If this is of some interest I will be making the boards available once the 
design is tested. That will allow you to customize the voltages if you need 
something different. 


I also have a board on the way that includes the above two voltages and +/- 12V 
@ 150 ma.  The voltages are tweakable so you can get +5.1 V and 3.4V and 
+/-12.3 - for instance. 


If this is of some interest let me know and I'll push them along.  If you have 
questions - ask. 


I also have a LM1117 board that is good for 800 ma each @ +5 and +3.3. Not so 
quiet but more current. That one requires a 12.6V AC CT transformer. Of course 
you can use a higher input voltage but it will reduce the maximum current. That 
is tested and for sale now. You can also get different voltages by adjusting 
components. 


Schematics, parts lists, and ordering instructions: 


http://spacetimepro.blogspot.com/2012/10/power-up.html


Simon 

 



Engineering is the art of making what you want from what you can get at a 
profit.
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Re: [time-nuts] Low noise power supplies?

[Tom Knox]

Hi Rick;
Starting with a hp supply this finesse regulator will really clean up the 
output. http://www.wenzel.com/documents/finesse.html
Best Wishes;
Thomas Knox


> Date: Wed, 30 Jan 2013 18:16:46 -0800
> From: rich...@karlquist.com
> To: time-nuts@febo.com
> Subject: [time-nuts] Low noise power supplies?
> 
> 
> I know this topic has been discussed in the past on the list, but
> a colleague is asking if there are any off the shelf low
> noise power supplies for testing oscillators.  Something
> a cut above an HP "brick" lab power supply etc.  They are hoping
> to avoid having to homebrew a power conditioning circuit.
> Did we ever arrive at a concensus as to the state of the art
> in homebrew power conditioning circuits?
> 
> Any help would be appreciated.
> 
> Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies?

[WB6BNQ]

YUP,

The C-130 aircraft uses larger than car battery size wet NiCd to fire up the
Genset that is used to start the Tubo-prop jet engines.  Definitely has lower
resistance then the Lead-Acid wet cell.

BillWB6BNQ

Arthur Dent wrote:

> >But the only NiCd I know about are the AA sized ones.
>
> I have some of the wet NiCd batteries that are capable of
> putting out 200A continuously. I'm assuming the internal
> resistance is pretty low. ;-)
>
> Arthur
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[time-nuts] Low noise power supplies?

[Arthur Dent]

>But the only NiCd I know about are the AA sized ones.

I have some of the wet NiCd batteries that are capable of 
putting out 200A continuously. I'm assuming the internal 
resistance is pretty low. ;-)

Arthur
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[time-nuts] Low noise power supplies?

[Mark Sims]

A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range.  
Their M1 26650 format cells are around 8 milliohms.  Most high capacity (>3000 
mAh) 18650 style lithium cells are around 10-15 milliohms.  
   
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Re: [time-nuts] Low noise power supplies?

[Bruce Griffiths]

Lester Veenstra wrote:

The typical test supply on a bench for clean VCO testing is a small gel cell
battery.  For a regulated power supply, make one using a 723. The 723 has
far lower noise out than the monolithic regulators.

   

Depends on the variety of 723 some are noisier than others.
Some use an internal zener reference, some use a bandgap reference.
The original used a zener reference.

Bruce

Lester B Veenstra  MØYCM K1YCM W8YCM
les...@veenstras.com

US Postal Address:
5 Shrine Club Drive
HC84 Box 89C
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GPS: 39.33675 N  78.9823527 W

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-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Richard (Rick) Karlquist
Sent: Wednesday, January 30, 2013 9:17 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Low noise power supplies?


I know this topic has been discussed in the past on the list, but a
colleague is asking if there are any off the shelf low noise power supplies
for testing oscillators.  Something a cut above an HP "brick" lab power
supply etc.  They are hoping to avoid having to homebrew a power
conditioning circuit.
Did we ever arrive at a concensus as to the state of the art in homebrew
power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies?

[Chris Albertson]

On Wed, Jan 30, 2013 at 9:05 PM, Jim Lux  wrote:
> On 1/30/13 8:28 PM, Chris Albertson wrote:
>
>> For once the "best" is also cheap:  Batteries.
>>
>> But not all batteries are the same.  You want one with low internal
>> resistance, so a lead acid flooded battery will be the best.
>
>
> Most NiCd have very low internal resistance.. much lower than lead acid

Really?  I'm talking about flooded cells not gel.  I think large
automotive engine start battery might only have 20 milliohms
resistance.   But the only NiCd I know about are the AA sized ones.
Not fair to compare.  Perhaps a size size NiCd would be even better.
I don't know.

Got a reference, Google did not turn up much.  I'd expect that some
place there might be a table.

I've powered resonably large transmitters with a bank of golf cart
batteries.  Not because I needed the low noise but because this was on
a sail boat in the ocean.
Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Low noise power supplies?

[Jim Lux]

On 1/30/13 8:28 PM, Chris Albertson wrote:


For once the "best" is also cheap:  Batteries.

But not all batteries are the same.  You want one with low internal
resistance, so a lead acid flooded battery will be the best.


Most NiCd have very low internal resistance.. much lower than lead acid.

But aside from batteries, Rick's question is interesting, and I'd turn 
it around a bit.. What "off the shelf catalog product" has the lowest 
noise?  Do you go get a linear regulated supply from someone like Acopian?


And even more interesting.. if you're concerned about efficiency and 
want to use a DC/DC switcher to convert some ratty DC supply (12V 
vehicle power, or a solar panel, for instance) to something really 
quiet, what's the best strategy, using off the shelf bricks and modules.


That is, I'm sure someone could do a fabulous job with a box full of Ls 
and Cs and discrete components and a couple months to design, prototype, 
and build.. but if someone came to you and said, we want a mobile 
microwave system to study propagation in 3 weeks because they just got 
permission to go up on some mountain.  Something like a CW carrier at 
tens of GHz multiplied up from your very quiet oscillator, and they're 
going to look at turbulence and scintillation in the path, so time 
scales of milliseconds to 1000s of seconds are important.


What would you order from Newark, Allied, mouser, etc. (assuming you 
have your OCXOs and such sitting around).

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Re: [time-nuts] Low noise power supplies?

[Chris Albertson]

On Wed, Jan 30, 2013 at 6:16 PM, Richard (Rick) Karlquist
 wrote:
>
> I know this topic has been discussed in the past on the list, but
> a colleague is asking if there are any off the shelf low
> noise power supplies for testing oscillators.  Something
> a cut above an HP "brick" lab power supply etc.

For once the "best" is also cheap:  Batteries.

But not all batteries are the same.  You want one with low internal
resistance, so a lead acid flooded battery will be the best.

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Low noise power supplies?

[Lester Veenstra]

The typical test supply on a bench for clean VCO testing is a small gel cell
battery.  For a regulated power supply, make one using a 723. The 723 has
far lower noise out than the monolithic regulators.  


Lester B Veenstra  MØYCM K1YCM W8YCM
les...@veenstras.com

US Postal Address:
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This e-mail and any documents attached hereto contain confidential or
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-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Richard (Rick) Karlquist
Sent: Wednesday, January 30, 2013 9:17 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Low noise power supplies?


I know this topic has been discussed in the past on the list, but a
colleague is asking if there are any off the shelf low noise power supplies
for testing oscillators.  Something a cut above an HP "brick" lab power
supply etc.  They are hoping to avoid having to homebrew a power
conditioning circuit.
Did we ever arrive at a concensus as to the state of the art in homebrew
power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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[time-nuts] Low noise power supplies?

[Richard (Rick) Karlquist]

I know this topic has been discussed in the past on the list, but
a colleague is asking if there are any off the shelf low
noise power supplies for testing oscillators.  Something
a cut above an HP "brick" lab power supply etc.  They are hoping
to avoid having to homebrew a power conditioning circuit.
Did we ever arrive at a concensus as to the state of the art
in homebrew power conditioning circuits?

Any help would be appreciated.

Rick Karlquist N6RK
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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[SAIDJACK]

Were getting of off the original thread about Electrolytics versus other  
caps a bit..
 
>A switcher at 2.2MHz does not have single frequency spikes in its  power
>spectrum, but a rather wideband distribution.
 
Yes, that's Fourier 101 basics.
 
But what matters to Time nuts is if the switcher is running close to 1.0MHz 
 or 2.0MHz, as the 10th or 5th harmonics of these would fall right into the 
phase  noise spectrum of the 10.0MHz output and may show up on the usual 
phase noise  plots.
 
It is also easier to filter out a ~2MHz carrier than a ~1MHz carrier from  
AM-modulating our 10MHz oscillator through the power supply lines. Most of 
the  noise will likely be on the input of the buck switcher, not the output.
 
With a 1MHz switcher, you could have a nasty spur at 10.01MHz right in the  
spectrum of interest. Running at 2.2MHz moves that spur 1MHz away from the 
10MHz  carrier, and the possibility of the switcher "injection locking" with 
 the 10MHz oscillator is reduced. This is easier to accomplish with a 
2.2MHz  switcher than a 1MHz switcher.
 
>but a load-dependent feedback loop that will
>change duty cycle  or frequency (depending on device) to maintain a target
>output. Check for yourself.
 
The part I listed as an example is a fixed frequency device. Stay away  
from variable frequency devices for anything Time Nuts related - that is my  
opinion.
 
>Try to get >90% efficiency for instance, from 24V down to 3.5V 5A.  
Unlikely you can work at 2MHz.

A) why would you need 3.5V at 5A for anything time-nuts related?
 
B) you could parallel two or three 2MHz devices to get 5A output power, and 
 synchronize them to each other
 
C) If you are consuming 17.5 Watts at 3.5V in the first place, then  why 
would you care about 90% efficiency versus 85% efficiency in time-nuts  
related projects? The difference is less than one Watt, and getting 85% from 
24V  
should be possible with the switchers that are out there.
 
We now have commercial Cesium Vapor atomic clocks running at 0.12W and  
less, so it should be possible to get power consumption down way below  17.5W 
for most time nuts related equipment I would think...
 
bye,
Said
 
 
In a message dated 11/28/2011 16:43:03 Pacific Standard Time,  
camar...@quantacorp.com writes:

A  switcher at 2.2MHz does not have single frequency spikes in its  power
spectrum, but a rather wideband distribution. It is not a fixed  frequency,
fixed duty cycle oscillator, but a load-dependent feedback loop  that will
change duty cycle or frequency (depending on device) to maintain  a target
output. Check for yourself.

Try to get >90% efficiency  for instance, from 24V down to 3.5V 5A. Unlikely
you can work at  2MHz.


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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Jose Camara]

A switcher at 2.2MHz does not have single frequency spikes in its power
spectrum, but a rather wideband distribution. It is not a fixed frequency,
fixed duty cycle oscillator, but a load-dependent feedback loop that will
change duty cycle or frequency (depending on device) to maintain a target
output. Check for yourself.

Try to get >90% efficiency for instance, from 24V down to 3.5V 5A. Unlikely
you can work at 2MHz.




-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of saidj...@aol.com
Sent: Monday, November 28, 2011 3:06 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

Hi Attila,
 
I like >2MHz switchers because they use small components (inductors  and 
capacitors) and are easier to filter out at our usual frequencies of
interest.
 
The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz  
and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur

issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH  
inductor for the same 1.8V, 500mA application example, a huge difference in 
size  and cost. The capacitor is also 22uF vs. 47uF, again a large size and 
cost  savings for the 2.2MHz part.
 
Not much of an efficiency difference between the 1MHz and 2MHz parts  
anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent

better at 1.1MHz. With proper layout these parts are extremely well behaved
and 
 don't have any noticeable ringing etc on the switch as older units did, 
and they  don't create a lot of noise when using shielded inductors.
 
bye,
Said
 
 
In a message dated 11/28/2011 14:22:58 Pacific Standard Time,  
att...@kinali.ch writes:

> Use  ceramic caps where vibration is not an issue. Use high frequency   
> (>2MHz) switchers wherever efficiency is required, otherwise use  linear  
> regulators.

Not really. If you want to have good  efficiency, then you want to stay
below 1MHz, otherwise switching loses get  too high. But the disadvantage
is that you have big and bulky capacitors  and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a  good compromise if
you can tolerate PFM (aka pulse skip) for low load  conditions. Going up
to 2MHz (and beyond) is only recomended if you are  severly space limited.


Attila Kinali


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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[SAIDJACK]

Hi Attila,
 
I like >2MHz switchers because they use small components (inductors  and 
capacitors) and are easier to filter out at our usual frequencies of  interest.
 
The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz  
and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur  
issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH  
inductor for the same 1.8V, 500mA application example, a huge difference in 
size  and cost. The capacitor is also 22uF vs. 47uF, again a large size and 
cost  savings for the 2.2MHz part.
 
Not much of an efficiency difference between the 1MHz and 2MHz parts  
anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent  
better at 1.1MHz. With proper layout these parts are extremely well behaved and 
 don't have any noticeable ringing etc on the switch as older units did, 
and they  don't create a lot of noise when using shielded inductors.
 
bye,
Said
 
 
In a message dated 11/28/2011 14:22:58 Pacific Standard Time,  
att...@kinali.ch writes:

> Use  ceramic caps where vibration is not an issue. Use high frequency   
> (>2MHz) switchers wherever efficiency is required, otherwise use  linear  
> regulators.

Not really. If you want to have good  efficiency, then you want to stay
below 1MHz, otherwise switching loses get  too high. But the disadvantage
is that you have big and bulky capacitors  and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a  good compromise if
you can tolerate PFM (aka pulse skip) for low load  conditions. Going up
to 2MHz (and beyond) is only recomended if you are  severly space limited.


Attila Kinali


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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Attila Kinali]

On Mon, 28 Nov 2011 16:16:58 -0500 (EST)
saidj...@aol.com wrote:

> Use foil caps to avoid vibration-microphonics. Very expensive, but hey you  
> get what you pay for. Use Tantalum caps if bulk bypassing is needed, using  
> multiple 100uF units if necessary. The design is not right if you need more 
> than  say 470uF anyways unless you are switching tens of amps as in an 
> Audio power  amp..

I can agree on that, though i also had a design where i used 5*100uF
and it was barely enough (a system that usually used just a couple of
mA, but occasionaly could draw up to 2A for half a second. Of course,
the power supply could only deliver about 500mA)
  
> Use ceramic caps where vibration is not an issue. Use high frequency  
> (>2MHz) switchers wherever efficiency is required, otherwise use linear  
> regulators.

Not really. If you want to have good efficiency, then you want to stay
below 1MHz, otherwise switching loses get too high. But the disadvantage
is that you have big and bulky capacitors and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a good compromise if
you can tolerate PFM (aka pulse skip) for low load conditions. Going up
to 2MHz (and beyond) is only recomended if you are severly space limited.


Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[SAIDJACK]

Hi guys,
 
yes, Electrolytics, the OS-CON are specified at an internal +20C  
temperature rise when running at rated AC current, and that's probably when 
they  are 
brand-new and have all of their initial capacitance. Temperature rise in  
high current apps will probably increase as the part ages and looses  
capacitance.
 
Electronics in an enclosure can easily run at +30C above ambient due  to 
self heating, so +50C to ambient on the capacitor can easily happen. With a  
30C ambient, we are looking at 80C on the cap, and are down to a year 
lifetime  again on the standard OS-con caps (they seem to have long-lifetime 
special  models available too which are probably much more expensive). Let's 
keep 
in mind  that the OS-Con caps standard lifetime versions are already very 
expensive in my  opinion.

Also, Sanyo specifies "lifetime" not MTBF! Assuming this means useful  
lifetime with less than 50% decrease in capacity, this may mean that the MTBF 
is 
 actually much lower than that, since many designs may not work properly 
with  -50% capacitance, or have more than +20C self heating on the cap.
 
We have to remember that it may work on a particular installation for years 
 on end especially if it used as a DC bypass cap without any AC current on 
it,  but when designing products we cannot rely on anecdotal information, 
but rather  have to do the math based on the parts' specsheet and the products 
expected  worst-case ambient environment.
 
In my opinion:
 
Use foil caps to avoid vibration-microphonics. Very expensive, but hey you  
get what you pay for. Use Tantalum caps if bulk bypassing is needed, using  
multiple 100uF units if necessary. The design is not right if you need more 
than  say 470uF anyways unless you are switching tens of amps as in an 
Audio power  amp..
 
Use ceramic caps where vibration is not an issue. Use high frequency  
(>2MHz) switchers wherever efficiency is required, otherwise use linear  
regulators.
 
Use electrolytics ONLY in external disposable low-cost power supplies, such 
 as the $15, 12V 1A Wall Wart supplies available at Mouser etc.
 
Just my own opinions..
 
bye,
Said
 
 
In a message dated 11/27/2011 23:22:08 Pacific Standard Time,  
att...@kinali.ch writes:

On Fri,  25 Nov 2011 22:25:37 -0800
Chris Albertson   wrote:

> One question:  How  does one avoid using electrolytic caps if you need
> (say) 1,000uF or  even 100uF.   Those would be some mighty big film
>  caps.

I think, aluminium electrolytics are meant, as these have a lot  of
"wear" and can die. 

Hence, you can use tantal or niob  electrolytics, which have a dry
eletrolyt.

Or you can use ceramics  which are already available at 100uF.

Attila Kinali

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Attila Kinali]

On Mon, 28 Nov 2011 01:05:22 -0800
gary  wrote:

> Ceramic caps can be microphonic. Just something to be on the look out. 
> Not so much with leaded ceramics, but more of a problem with surface mounts.

Ceramic caps have a lot of other problems too, like capacitance
derating on increasing voltage. Some types go down to 80% of rated
capacity when driven to the max rated voltage.
 
> Tantalums are prone to overvoltage failure. Best to really overspec them 
> regarding voltage.

Uhmm.. overspec? The rated voltage is the maximum allowed voltage.
Like something you should never cross. That's why we have these
odd numbers like 16V. They are not intended to be used at 16V but
rather at standard voltages like 12V.


> Note that some LDOs are not stable with really low ESR bypass. There are 
> app notes on this. 

Actually, the datasheet of any LDO (or power regulator) should define
the stable operation output capacitance and ESR. If you work outside
the speced range.. well.. your own fault if you get oscillation ;-)



Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[gary]

Ceramic caps can be microphonic. Just something to be on the look out. 
Not so much with leaded ceramics, but more of a problem with surface mounts.


Tantalums are prone to overvoltage failure. Best to really overspec them 
regarding voltage.


Note that some LDOs are not stable with really low ESR bypass. There are 
app notes on this. I've stated my preference for p-fet pass devices, or 
better yet, shunt regulators. The PNP pass devices will need feedforward 
compensation if the ESR is too low.



On 11/27/2011 11:21 PM, Attila Kinali wrote:

On Fri, 25 Nov 2011 22:25:37 -0800
Chris Albertson  wrote:


One question:  How does one avoid using electrolytic caps if you need
(say) 1,000uF or even 100uF.   Those would be some mighty big film
caps.


I think, aluminium electrolytics are meant, as these have a lot of
"wear" and can die.

Hence, you can use tantal or niob electrolytics, which have a dry
eletrolyt.

Or you can use ceramics which are already available at 100uF.

Attila Kinali



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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Attila Kinali]

On Fri, 25 Nov 2011 22:25:37 -0800
Chris Albertson  wrote:

> One question:  How does one avoid using electrolytic caps if you need
> (say) 1,000uF or even 100uF.   Those would be some mighty big film
> caps.

I think, aluminium electrolytics are meant, as these have a lot of
"wear" and can die. 

Hence, you can use tantal or niob electrolytics, which have a dry
eletrolyt.

Or you can use ceramics which are already available at 100uF.

Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[ehydra]

I molt them in a high-power charge-pump. The same with WIMA MKS.

At normal usage they will last forever and work even at low temperature 
whereas normal Al caps won't.


- Henry


gary schrieb:
At sane temperatures, OSCONs are very good. Who runs their gear hot 
enough to boil water?

http://edc.sanyo.com/pdf/e_oscon.pdf


--
ehydra.dyndns.info

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Jim Lux]

On 11/26/11 11:13 AM, Chris Albertson wrote:

On Fri, Nov 25, 2011 at 10:36 PM, Raj  wrote:

How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)

http://sound.westhost.com/project15.htm



The above actually uses several quite large electrolytic.   It is a
good example of why you NEED to use them.

Maybe someone can post a schematic of a simple  5V 5A power supply
that does NOT use any electro caps.




WHat ripple/regulation?

3 phase power and no filter gives you 8% ripple.




Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Chris Albertson]

On Fri, Nov 25, 2011 at 10:36 PM, Raj  wrote:
> How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)
>
> http://sound.westhost.com/project15.htm
>

The above actually uses several quite large electrolytic.   It is a
good example of why you NEED to use them.

Maybe someone can post a schematic of a simple  5V 5A power supply
that does NOT use any electro caps.


Chris Albertson
Redondo Beach, California

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[time-nuts] Low noise power supplies - dont' use Electrolytics

[ed breya]

Off topic: Actually, you can make almost anything withstand almost 
any conditions TEMPORARILY - it depends on the packaging too. If you 
wrap a circuit that can work at 100 deg C in a water jacket wrapped 
in high temperature insulation, you can keep it going until most of 
the water has boiled away. That's how those so-called fire safes can 
protect papers against fire for a certain amount of time - the 
insulation is hydrated gypsum, which insulates and provides cooling water.


On topic: You can use whatever capacitors make sense for the 
application, but you know that the hotter they need to run, the less 
life is to be expected.


Ed

On Sat, Nov 26, 2011 at 2:13 AM, gary 
<lists at 
lazygranch.com> wrote:

> At sane temperatures, OSCONs are very good. Who runs their gear hot enough
> to boil water?

Sat Nov 26 12:53:13 UTC 2011  Bob Paddock bob.paddock at gmail.com  wrote:

National Fire Protection Agency (NFPA) 2007 edition of their design
regulations state the electronics worn by Fire Fighters must work at
500'F for five minutes.
In the Paper Pusher's mind the Kevlar clothing can withstand those
temperatures, therefor anything else in the Universe can too.
Never under estimate the bureaucratic mind...




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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Bob Paddock]

On Sat, Nov 26, 2011 at 2:13 AM, gary  wrote:
> At sane temperatures, OSCONs are very good. Who runs their gear hot enough
> to boil water?

National Fire Protection Agency (NFPA) 2007 edition of their design
regulations state the electronics worn by Fire Fighters must work at
500'F for five minutes.
In the Paper Pusher's mind the Kevlar clothing can withstand those
temperatures, therefor anything else in the Universe can too.
Never under estimate the bureaucratic mind...

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Poul-Henning Kamp]

In message 
, Chris Albertson writes:

>One question:  How does one avoid using electrolytic caps if you need
>(say) 1,000uF or even 100uF.   Those would be some mighty big film caps.

One detail, often overlooked, is that electrolytics seldom are
dimensioned very precisely, mostly because they do come with such
big capacity but also because them have very big tolerances, +/-
50% is not uncommon.

Another effect that causes overdimensioning is that they are not very
good capacitors, in particular at higher frequency.

I have in a couple of instances replaced electrolytics with film-caps
and gotten away with less than 1% of the original capacitance by doing
a bit of calculations and measurements on the actual circuit.

In one case, an audio circuit had 1000uF for a handful of opamps,
using 4.7uF of good film capacitors instead reduced THD by 80%.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[gary]

At sane temperatures, OSCONs are very good. Who runs their gear hot 
enough to boil water?

http://edc.sanyo.com/pdf/e_oscon.pdf




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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Steve .]

To second the older electronics:

I maintain nearly 100 analytical instruments. The old designs(1970-late
80's) are almost all electrolytic caps and none of the caps have ever
failed. When I do find a bad cap it's always in a modern design. A high
frequency switcher with under rated caps. When i say under rated i mean
take the peak figure and multiple it by two, that's the real part value.

My opinion, bad designs.

Steve

On Sat, Nov 26, 2011 at 1:25 AM, Chris Albertson
wrote:

> Many of us have seen electronic equipment last longer then one year.
> Some of use even have still working antiques with old eletro caps.
> Those short lifetimes assume a worse case, usually with a very high
> ripple current.   IOf you can reduce the ripple the MTBF goes up.
>
> One question:  How does one avoid using electrolytic caps if you need
> (say) 1,000uF or even 100uF.   Those would be some mighty big film
> caps.
>
>
>
>
> On Fri, Nov 25, 2011 at 10:06 PM,   wrote:
> > Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their
> > website state "50K Hrs at 50C".
> >
> > This means only 6250 MTBF hours at 80C for one single cap. MTBF gets
>  worse
> > the more caps are being used of course. I have seen some  Panasonic
> > electrolytics state only 2000 hours MTBF at temperature in  their
> datasheets.
> >
> > That's not even one year before a mean failure occurs making these
> useless
> > in high-reliability applications.
> >
> > Note also that caps in high AC current situations (Buck DC-DC switcher
> > input cap for example) will self heat due to internal resistance, making
> things
> >  even worse. This is probably one of the main failure reasons for PC
> > motherboards.
> >
> > And that's with name brand parts, it's even worse if one ends up buying
> > counter-fit or non-name-brand Electrolytics.
> >
> > Some of our competitors use Electrolytics all over the place (we don't
>  use
> > any electrolytics) - that's been good for our business.
> >
> > bye,
> > Said
> >
> >
> > In a message dated 11/24/2011 17:08:42 Pacific Standard Time,
> > li...@lazygranch.com writes:
> >
> > I'm not  familiar with rubycon caps. The low ESR large value caps are
> > "organic  semiconductor." OSCON is a common brand from Sanyo. Finding the
> > ultimate  cap is nearly as much fun as finding the ultimate LDO. Check
> > out Nichicon.  Or you can stick with the Rubycon. Glancing at their
> > website, they seem to  copy the Nichicon product  line.
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Raj]

How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)

http://sound.westhost.com/project15.htm


>One question:  How does one avoid using electrolytic caps if you need
>(say) 1,000uF or even 100uF.   Those would be some mighty big film
>caps.


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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Chris Albertson]

Many of us have seen electronic equipment last longer then one year.
Some of use even have still working antiques with old eletro caps.
Those short lifetimes assume a worse case, usually with a very high
ripple current.   IOf you can reduce the ripple the MTBF goes up.

One question:  How does one avoid using electrolytic caps if you need
(say) 1,000uF or even 100uF.   Those would be some mighty big film
caps.




On Fri, Nov 25, 2011 at 10:06 PM,   wrote:
> Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their
> website state "50K Hrs at 50C".
>
> This means only 6250 MTBF hours at 80C for one single cap. MTBF gets  worse
> the more caps are being used of course. I have seen some  Panasonic
> electrolytics state only 2000 hours MTBF at temperature in  their datasheets.
>
> That's not even one year before a mean failure occurs making these useless
> in high-reliability applications.
>
> Note also that caps in high AC current situations (Buck DC-DC switcher
> input cap for example) will self heat due to internal resistance, making 
> things
>  even worse. This is probably one of the main failure reasons for PC
> motherboards.
>
> And that's with name brand parts, it's even worse if one ends up buying
> counter-fit or non-name-brand Electrolytics.
>
> Some of our competitors use Electrolytics all over the place (we don't  use
> any electrolytics) - that's been good for our business.
>
> bye,
> Said
>
>
> In a message dated 11/24/2011 17:08:42 Pacific Standard Time,
> li...@lazygranch.com writes:
>
> I'm not  familiar with rubycon caps. The low ESR large value caps are
> "organic  semiconductor." OSCON is a common brand from Sanyo. Finding the
> ultimate  cap is nearly as much fun as finding the ultimate LDO. Check
> out Nichicon.  Or you can stick with the Rubycon. Glancing at their
> website, they seem to  copy the Nichicon product  line.
>
>
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>



-- 

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[SAIDJACK]

Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their  
website state "50K Hrs at 50C".
 
This means only 6250 MTBF hours at 80C for one single cap. MTBF gets  worse 
the more caps are being used of course. I have seen some  Panasonic 
electrolytics state only 2000 hours MTBF at temperature in  their datasheets.
 
That's not even one year before a mean failure occurs making these useless  
in high-reliability applications.
 
Note also that caps in high AC current situations (Buck DC-DC switcher  
input cap for example) will self heat due to internal resistance, making things 
 even worse. This is probably one of the main failure reasons for PC  
motherboards.
 
And that's with name brand parts, it's even worse if one ends up buying  
counter-fit or non-name-brand Electrolytics.

Some of our competitors use Electrolytics all over the place (we don't  use 
any electrolytics) - that's been good for our business. 
 
bye,
Said
 
 
In a message dated 11/24/2011 17:08:42 Pacific Standard Time,  
li...@lazygranch.com writes:

I'm not  familiar with rubycon caps. The low ESR large value caps are 
"organic  semiconductor." OSCON is a common brand from Sanyo. Finding the 
ultimate  cap is nearly as much fun as finding the ultimate LDO. Check 
out Nichicon.  Or you can stick with the Rubycon. Glancing at their 
website, they seem to  copy the Nichicon product  line.


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Attila Kinali]

On Thu, 24 Nov 2011 11:45:05 -0700
Kevin Rosenberg  wrote:

> > 78xx Regulators are quite noisy. You can use them to filter the
> > noise of a cheap DC/DC converter, but i wouldnt use them feed
> > high precision electronics. There are a lot better designs these days.
> 
> Would you mind recommending some low-noise regulators? Perhaps for
> both low and high current applications? I'm looking for 12V to power 
> some OXCOs to be used a reference oscillator for a phase noise tester.
> On the higher current side, maybe to power a rubidium (or at least
> filter the switcher).

As Bob Camp already said, Linear has some low noise LDO's.
Also Ti and Analog are worth a look. All three of them also have
a lot of app notes describing how to filter power supply noise
for instrumentation and PLL applications.

A quick googling revealed the following guides:
http://www.ti.com/lit/an/slyt201/slyt201.pdf
http://www.designers-guide.org/Design/bypassing.pdf

HTH
Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Kevin Rosenberg]

On Nov 24, 2011, at 4:46 PM, Bob Camp wrote:
> The Linear LT1764 is reasonably quiet / high current / low dropout. Don't 
> count on getting all three at once.

Thanks, Bob!

Kevin


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Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board

[gary]

The LTC datasheet "crows" about low current in dropout. Yeah, it's worth 
crowing about since not all chip use what is called a "sat catcher" 
circuit. High current in dropout with PNP pass devices can be a problem. 
I've seen Micrel regulators that are horrible in dropout. The sat 
catcher is yet another feedback loop, so it is best to stay out of low 
dropout if possible.


Generally when I buy a LDO, I use the type with a P-fet rather than PNP. 
I'm not sure if any of these exist with low noise. [I'm usually more 
concerned with stability.] TI makes good ones. The P-fet pass device 
doesn't need a sat catcher, so there is one less loop to worry about. 
Having designed both types, I find the P-fet pass much easier to 
stabilize. Bipolar devices don't isolated as well as MOS.


I'm not familiar with rubycon caps. The low ESR large value caps are 
"organic semiconductor." OSCON is a common brand from Sanyo. Finding the 
ultimate cap is nearly as much fun as finding the ultimate LDO. Check 
out Nichicon. Or you can stick with the Rubycon. Glancing at their 
website, they seem to copy the Nichicon product line.


On 11/24/2011 1:37 PM, Tim wrote:

Hi All
,
I find it interesting that this subject came up just as I was looking
into cleaning up some of my supplies that power my RB's.

Anyway

I just bought two of these to play with

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=130605436528

and they're based on this device...

http://www.linear.com/product/LT1764

regards

Tim




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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Bob Camp]

Hi

The Linear LT1764 is reasonably quiet / high current / low dropout. Don't count 
on getting all three at once.

Bob



On Nov 24, 2011, at 12:45 PM, Kevin Rosenberg  wrote:

>> 78xx Regulators are quite noisy. You can use them to filter the
>> noise of a cheap DC/DC converter, but i wouldnt use them feed
>> high precision electronics. There are a lot better designs these days.
> 
> Hi Attila,
> 
> Would you mind recommending some low-noise regulators? Perhaps for
> both low and high current applications? I'm looking for 12V to power 
> some OXCOs to be used a reference oscillator for a phase noise tester.
> On the higher current side, maybe to power a rubidium (or at least
> filter the switcher).
> 
> Thanks very much,
> 
> Kevin
> 
> 
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Re: [time-nuts] Low noise power supplies for time nuts circuitry - 40μV Adjustable Voltage Regulator Board

[Tim]

Hi All
,
I find it interesting that this subject came up just as I was looking 
into cleaning up some of my supplies that power my RB's.


Anyway

I just bought two of these to play with

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=130605436528

and they're based on this device...

http://www.linear.com/product/LT1764

regards

Tim


--
VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Azelio Boriani]

The -12V in the TBolt is not used for the serial port. the HIN232 of the
TBolt goes from the +5V only, it generates the + and - by the usual
switched capacitor technique common to other RS232 interfaces (ADM232,
MAX3221 and so on). The -12V powers the LT1014 quad precision opamp that I
presume handles the EFC, so care must be taken about the -12 although the
PSRR of the opamp comes to the rescue.

On Thu, Nov 24, 2011 at 8:25 PM,  wrote:

> When you design a regulator, lots of gain is not a criteria in the error
> amp. (Who needs microvolt accuracy?) High gain generally means two gain
> stages, which in turn makes it difficult to compensate when driving
> reactive loads. Thus most op amps are generally a bad idea for an error amp
> in a regulator.
>
> Noise needs to be defined. Generally it means broadband noise. But if your
> regulator is on the verge of oscillation when the load current or line
> voltage changes, who cares if the broadband noise is low?
>
> This thread is starting to baffle me. Simply dig up a low noise regulator
> chip. LTC comes to mind. Or troll the net for audiophile shunt designs if
> you are going to roll your own.
>
> What you see done in design often is dubious. Just because it is built,
> doesn't mean it is good. (Hey, there are doctors that give bad medical
> advice.) You need to evaluate existing designs for your application.
>
> It pays to read the datasheet religiously. Some of these high accuracy
> regulators can't handle low ESR caps on the output.
> -Original Message-
> From: Joe Gwinn 
> Sender: time-nuts-boun...@febo.com
> Date: Thu, 24 Nov 2011 10:14:35
> To: 
> Reply-To: Discussion of precise time and frequency measurement
> 
> Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry
>
> At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote:
> >Message: 3
> >Date: Thu, 24 Nov 2011 13:22:38 +0100
> >From: Attila Kinali 
> >To: Discussion of precise time and frequency measurement
> >   
> >Subject: Re: [time-nuts] Low noise power supplies for time nuts
> >   circuitry
> >Message-ID: <2024132238.0c810b78.att...@kinali.ch>
> >Content-Type: text/plain; charset=US-ASCII
> >
> >On Wed, 23 Nov 2011 04:50:49 -0800
> >Chuck Forsberg WA7KGX N2469R  wrote:
> >
> >>  How well would a pair of cascaded 3 terminal regulators do - say a 7815
> >>  feeding a 7812.
> >
> >78xx Regulators are quite noisy. You can use them to filter the
> >noise of a cheap DC/DC converter, but i wouldnt use them feed
> >high precision electronics. There are a lot better designs these days.
>
> What I see done in low-noise circuits is a low-noise opamp used as a
> linear voltage regulator to clean up the output of a 78xx or the like
> regulator.
>
> Joe Gwinn
>
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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[lists]

When you design a regulator, lots of gain is not a criteria in the error amp. 
(Who needs microvolt accuracy?) High gain generally means two gain stages, 
which in turn makes it difficult to compensate when driving reactive loads. 
Thus most op amps are generally a bad idea for an error amp in a regulator. 

Noise needs to be defined. Generally it means broadband noise. But if your 
regulator is on the verge of oscillation when the load current or line voltage 
changes, who cares if the broadband noise is low? 

This thread is starting to baffle me. Simply dig up a low noise regulator chip. 
LTC comes to mind. Or troll the net for audiophile shunt designs if you are 
going to roll your own. 

What you see done in design often is dubious. Just because it is built, doesn't 
mean it is good. (Hey, there are doctors that give bad medical advice.) You 
need to evaluate existing designs for your application. 

It pays to read the datasheet religiously. Some of these high accuracy 
regulators can't handle low ESR caps on the output. 
-Original Message-
From: Joe Gwinn 
Sender: time-nuts-boun...@febo.com
Date: Thu, 24 Nov 2011 10:14:35 
To: 
Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry

At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote:
>Message: 3
>Date: Thu, 24 Nov 2011 13:22:38 +0100
>From: Attila Kinali 
>To: Discussion of precise time and frequency measurement
>   
>Subject: Re: [time-nuts] Low noise power supplies for time nuts
>   circuitry
>Message-ID: <2024132238.0c810b78.att...@kinali.ch>
>Content-Type: text/plain; charset=US-ASCII
>
>On Wed, 23 Nov 2011 04:50:49 -0800
>Chuck Forsberg WA7KGX N2469R  wrote:
>
>>  How well would a pair of cascaded 3 terminal regulators do - say a 7815
>>  feeding a 7812.
>
>78xx Regulators are quite noisy. You can use them to filter the
>noise of a cheap DC/DC converter, but i wouldnt use them feed
>high precision electronics. There are a lot better designs these days.

What I see done in low-noise circuits is a low-noise opamp used as a 
linear voltage regulator to clean up the output of a 78xx or the like 
regulator.

Joe Gwinn

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Kevin Rosenberg]

On Nov 23, 2011, at 5:50 AM, Chuck Forsberg WA7KGX N2469R wrote:
> How sensitive are each of a Thunderbolt's 3 supplies to noise?

This doesn't break down the sensitivities to noise, but Tom shows
a range of TBolt output noise for different 3 voltage power supplies:
http://www.leapsecond.com/pages/tbolt/noise.htm

My suspicion is the -12V is the least sensitive as I heard that it
is only used for the RS-232 port. I think either the the +5V which
controls the electronics (including things like comparators) and
the +12V (which controls the heater to the OXCO) are both noise
sensitive. I think the +5V will be the most sensitive.

For the PRS10 Rb, two 24V inputs are provided. A higher current
for the heater and a lower current for the electronics. To my
mind, that makes it likely the electronics (+5V on the TBolt)
are the most sensitive.

Maybe someone will actually have data to show.

Kevin


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Kevin Rosenberg]

> 78xx Regulators are quite noisy. You can use them to filter the
> noise of a cheap DC/DC converter, but i wouldnt use them feed
> high precision electronics. There are a lot better designs these days.

Hi Attila,

Would you mind recommending some low-noise regulators? Perhaps for
both low and high current applications? I'm looking for 12V to power 
some OXCOs to be used a reference oscillator for a phase noise tester.
On the higher current side, maybe to power a rubidium (or at least
filter the switcher).

Thanks very much,

Kevin


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Joe Gwinn]

At 2:28 PM + 11/24/11, time-nuts-requ...@febo.com wrote:

Message: 3
Date: Thu, 24 Nov 2011 13:22:38 +0100
From: Attila Kinali 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Low noise power supplies for time nuts
circuitry
Message-ID: <2024132238.0c810b78.att...@kinali.ch>
Content-Type: text/plain; charset=US-ASCII

On Wed, 23 Nov 2011 04:50:49 -0800
Chuck Forsberg WA7KGX N2469R  wrote:


 How well would a pair of cascaded 3 terminal regulators do - say a 7815
 feeding a 7812.


78xx Regulators are quite noisy. You can use them to filter the
noise of a cheap DC/DC converter, but i wouldnt use them feed
high precision electronics. There are a lot better designs these days.


What I see done in low-noise circuits is a low-noise opamp used as a 
linear voltage regulator to clean up the output of a 78xx or the like 
regulator.


Joe Gwinn

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[shalimr9]

>From a noise and long term stability standpoint, it would not be better than 
>the last device in the chain, and the 78xx series is not great.
But you would gain additional ripple and line variation rejection, so if that's 
what you need to do, it may help.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-Original Message-
From: Chuck Forsberg WA7KGX N2469R 
Sender: time-nuts-boun...@febo.com
Date: Wed, 23 Nov 2011 04:50:49 
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Low noise power supplies for time nuts circuitry

How well would a pair of cascaded 3 terminal regulators do - say a 7815 
feeding a 7812.
How sensitive are each of a Thunderbolt's 3 supplies to noise?

On 11/23/2011 04:13 AM, Attila Kinali wrote:
> On Tue, 22 Nov 2011 12:38:43 -0500
> Bob Camp  wrote:
>
>> There are a couple of circuits (low noise op-amp based)
>> that can generate lower noise than what he's shown.
> What circuits would that be?
>
>   Attila Kinali
>

-- 
Chuck Forsberg WA7KGX N2469R c...@omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
   Omen Technology Inc  "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Attila Kinali]

On Wed, 23 Nov 2011 04:50:49 -0800
Chuck Forsberg WA7KGX N2469R  wrote:

> How well would a pair of cascaded 3 terminal regulators do - say a 7815 
> feeding a 7812.

78xx Regulators are quite noisy. You can use them to filter the
noise of a cheap DC/DC converter, but i wouldnt use them feed
high precision electronics. There are a lot better designs these days.

Attila Kinali
-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Chuck Forsberg WA7KGX N2469R]

How well would a pair of cascaded 3 terminal regulators do - say a 7815 
feeding a 7812.

How sensitive are each of a Thunderbolt's 3 supplies to noise?

On 11/23/2011 04:13 AM, Attila Kinali wrote:

On Tue, 22 Nov 2011 12:38:43 -0500
Bob Camp  wrote:


There are a couple of circuits (low noise op-amp based)
that can generate lower noise than what he's shown.

What circuits would that be?

Attila Kinali



--
Chuck Forsberg WA7KGX N2469R c...@omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
  Omen Technology Inc  "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430


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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[Attila Kinali]

On Tue, 22 Nov 2011 12:38:43 -0500
Bob Camp  wrote:

> 
> There are a couple of circuits (low noise op-amp based)
> that can generate lower noise than what he's shown.

What circuits would that be?

Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[ehydra]

li...@lazygranch.com schrieb:
The bozos at Broadcom have actually patented using shunt regulation in their chips. Good luck enforcing that patent. 


Must be a joke or misunderstanding.

Look for example in the datasheet of TCA440. A really old IC. In the 
internal circuit displayed is a diode shunt regulator serving at the 
same time as reference divider.


- Henry

--
ehydra.dyndns.info

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Re: [time-nuts] Low noise power supplies for time nuts circuitry

[lists]

Yes, load isolation is a valuable feature I left out. Perhaps the key feature. 
The audio designers like it for channel separation.  
--Original Message--
From: ed breya
Sender: time-nuts-boun...@febo.com
To: time-nuts@febo.com
ReplyTo: Discussion of precise time and frequency measurement
Subject: [time-nuts]  Low noise power supplies for time nuts circuitry
Sent: Nov 22, 2011 2:17 PM

The shunt regulator also serves to isolate load current fluctuations 
from the main supply, since it makes it appear as a constant 
resistance, current, or power load, depending on the design. This can 
eliminate cross-talk between various circuitry.

For example, I just made one for my new 5065A LED clock design. It 
makes 4 V for the display, and is able to absorb the nasty 90 mA to 
250 mA local range caused by the LED numeric and scan load, but the 
steps are virtually invisible to the +5 V supply - it looks like 
about a 4 ohm resistive load into about 4 V source.

Ed


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