Re: [neonixie-l] Re: Linear power supplies for nixies

['threeneurons' via neonixie-l]

On Tuesday, October 6, 2015 at 3:50:51 PM UTC-7, gregebert wrote:
>
> I dont know if it's still common practice, but many radios and small TVs 
> in the US in the 1960's & 1970's had a 'hot-chassis' where one side of the 
> AC line was connected to the metal interior chassis. Obviously, these 
> devices had non-conductive (usually plastic) cases. Polarized cords 
> supposedly ensured the neutral side was connected to the chassis, but 
> extension cords etc left it a 50-50 chance it was electrically hot. I cant 
> recall if any of these were UL listed, or not.
>


Those are the "All American 5" (AA5) tube radios, which first came out in 
the late 30's. Various tube line ups, which changed as more modern tubes 
became available. Still being made into the early 70's. There were also TV 
sets made with hot chassis and series heater strings. Usually "portables". 
"Portable" being a 35 lb box with a handle on top.

UL standards get superseded by newer ones, continually. I remember one time 
when there were 3 standards covering consumer products. I contacted UL, to 
ask which one I should use for a new product. Their reply was "pick one". 
But they also said, that the older ones would be phased out, and eventually 
there would only be one. So the AA5 probably met some long defunct UL 
standard. UL is not a government regulatory agency, but a private 
organization setup by the insurance industry.

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/0d7d6c10-a3fb-4137-9cbd-ab4c65cb97ba%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[Instrument Resources of America]

On 10/6/2015 3:50 PM, gregebert wrote:
I dont know if it's still common practice, but many radios and small 
TVs in the US in the 1960's & 1970's had a 'hot-chassis' where one 
side of the AC line was connected to the metal interior chassis. 
Obviously, these devices had non-conductive (usually plastic) cases. 
Polarized cords supposedly ensured the neutral side was connected to 
the chassis, but extension cords etc left it a 50-50 chance it was 
electrically hot. I cant recall if any of these were UL listed, or not.
Those chassis IIRC were insulated from the cabinets with nylon/plastic 
bushings.   I think even the control shafts were also insulated from the 
chassis just in case one of the control knobs came off.


You would think that if hot-chassis devices were "safe", then usage of 
a pseudo-isolation transformer would be safer. I was probably 12 years 
old when I opened-up my first hot-chassis radio (yes, it was 
unplugged) and couldn't believe my eyes when I saw the power-connector 
tied to the large all-metal chassis.


And for you vacuum-tube enthusiasts, you may have wondered why there 
was a tube with a 35-volt filament (35W4). That's because the 
filaments were wired in-series to the AC line, and the remaining tubes 
had 12.6-volt filaments.
Except for the audio output tube which had a "50" volt filament, e.g. 
50C5 or 50B5.   Ira






--
You received this message because you are subscribed to the Google 
Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send 
an email to neonixie-l+unsubscr...@googlegroups.com 
.
To post to this group, send email to neonixie-l@googlegroups.com 
.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/cd819a31-c745-4ac8-91a6-a9118b094ffd%40googlegroups.com 
.

For more options, visit https://groups.google.com/d/optout.


--
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/56147FF8.8090105%40HUGHES.NET.
For more options, visit https://groups.google.com/d/optout.
<>

Re: [neonixie-l] Re: Linear power supplies for nixies

[gregebert]

I dont know if it's still common practice, but many radios and small TVs in 
the US in the 1960's & 1970's had a 'hot-chassis' where one side of the AC 
line was connected to the metal interior chassis. Obviously, these devices 
had non-conductive (usually plastic) cases. Polarized cords supposedly 
ensured the neutral side was connected to the chassis, but extension cords 
etc left it a 50-50 chance it was electrically hot. I cant recall if any of 
these were UL listed, or not.

You would think that if hot-chassis devices were "safe", then usage of a 
pseudo-isolation transformer would be safer. I was probably 12 years old 
when I opened-up my first hot-chassis radio (yes, it was unplugged) and 
couldn't believe my eyes when I saw the power-connector tied to the large 
all-metal chassis. 

And for you vacuum-tube enthusiasts, you may have wondered why there was a 
tube with a 35-volt filament (35W4). That's because the filaments were 
wired in-series to the AC line, and the remaining tubes had 12.6-volt 
filaments.





-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/cd819a31-c745-4ac8-91a6-a9118b094ffd%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[Dekatron42]

I do not know anything about this topic, that's why I asked.

I was told by a friend that the Low Voltage Directive in the EN61010 
standard was the right place to look for answers, so I did and found some 
details but I do not understand it all. I found 
this http://www.ni.com/white-paper/2827/en/ which talks about instruments 
and isolation, which is interesting as it also mentions transformers and 
the categories used. So I emailed two transformer manufacturers and the 
Swedish National Electrical Safety Board and asked them about the use of 
transformer winding usage and also asked my insurance company.

One transformer manufacturer answered me that as long as the combined 
voltage of the secondary plus primary winding is within the isolation 
category, and voltage for the primary isolation barrier, it would of course 
work and be within the approval limits but they did not recommend it for a 
few reasons, the foremost reason being that a transformer is not tested for 
this connection and it would probably fail (not due to the voltages used 
but more so because there is no test for this condition) in an approval 
test under this condition and/or at least need an expensive new way of 
testing to be performed for an approval - being within the approval limits 
is not the same as being approved when used in a way that the approval 
testing has not tested nor taken into account they told me. One other 
reason for not using this way of connecting the windings is because the 
heating of the transformer windings in this condition is not taken into 
consideration when the transformer is designed and that could affect 
performance.

When it comes to the insurance question it would not be ok if it did not 
have an approval and was the starting cause for the fire, if it had an 
approval it would be just fine.

So, it will probably work ok but it might be hard to get an approval and 
therefore not good to use if it catches fire, at least in Sweden and with 
my insurance company. So I'll stick with transformer bought from reliable 
transformer manufacturers for now.

/Martin

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/df368542-835c-4b09-86d6-40640cf80e4e%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[David Forbes]

I once had to fix our neighbors' coffee grinder at Burning Man. I found that it 
had a blown thermal fuse, probably because they were using a household coffee 
grinder for an espresso bar which served dozens of cups a day.


Solution:
1. Bypass thermal fuse
2. Write on the case "For playa use only. Safety systems disabled"
3. Safety third!


On 10/5/2015 1:32 PM, Charles MacDonald wrote:

I can see the sort of thinking that going into passing those tests when I
overworked a blender and it stopped working.  The maker had buried a thermal
fuse inside the motor. which had opened.  not serviceable but it would not catch
fire in the UL/CSA tests.


--
David Forbes, Tucson, AZ

--
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/5612E045.2000802%40dakotacom.net.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[Charles MacDonald]

On 15-10-05 03:44 AM, Jim_Z wrote:


Also note that in the case of power supplies it's not important to UL
whether they really work or not- only that they perform to the UL
requirements which don't typically specify performance values.
Jim


Thinking of this thread bought back a converstaion I had in the 1980s 
with one of the senior people at what was Commodore Canada.  They were 
just coming out with the Vic-20 and the topic of the conversation got on 
to CSA.


Basically he told me that they were expected to submit two production 
samples of each product. CSA would take these and literally torture them 
to death.  for a pwer supply for example, short the output and make sure 
the fuse blows or it otherwise shuts down.  This after drawing twice the 
rated current for a while and getting neither smoke nor flames.  He also 
talked about the lab dousing the unit with a flammable substance and 
making sure it did not catch fire.


(at that time before NAFTA items needed a CSA sticker in canada and a UL 
sticker in the USA.  Now several labs can do the tests and put a "C" or 
"us" or both depending on whose standards are met)


I am sure he was exaggerating somewhat, but his voice was exasperated 
when he mentioned that they them charged extra if he wanted the test 
items, which were now totally unusable even for parts - back


I can see the sort of thinking that going into passing those tests when 
I overworked a blender and it stopped working.  The maker had buried a 
thermal fuse inside the motor. which had opened.  not serviceable but it 
would not catch fire in the UL/CSA tests.



--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca  Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

--
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/5612DE45.4070808%40zeusprune.ca.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[Jim_Z]

Having worked for UL as an engineer I have a few comments.
UL does not "approve" anything- they List, Recognize and Classify items. 
"Approval"  implies that an item can be used without regards to its limited 
testing by UL. The UL lawyers hate the term "Approved By UL" and 
routinely  send out letters to the corporate abusers of that terminology.
In the case of power supplies they are usually "Recognized" components 
meaning that they are tested to certain parameters but are dependent on the 
actual environment they are applied to (that is the backwards UL 
symbol). For instance, if a  previously UL "Recognized" power supply is 
installed in a computer that is submitted for "Listing" and it is used 
within its UL defined "Recognition" than limited investigation is required.
Also note that in the case of power supplies it's not important to UL 
whether they really work or not- only that they perform to the UL 
requirements which don't typically specify performance values.
Jim 

On Wednesday, September 30, 2015 at 9:14:11 PM UTC-7, gregebert wrote:

> I did some research on UL/CSA approved transformers, and there is a 
> requirement that all windings withstand a minimum breakdown voltage, even 
> if they are intended to be connected together, such as dual-primaries. 
> Depending upon the VA rating and the voltage, the breakdown must be between 
> 1050 and 4000 V RMS according to how I read the spec (UL5058-2 / CSA C22.2 
> #66). The test is conducted between 1 winding, and all other windings and 
> the core combined and at elevated temperature. There are copies of the spec 
> online.
>
> I knew there had to be some amount of isolation, but I did not realize it 
> was *that* high. While I would never expose or touch anything that is 
> supposedly "isolated", it does reassure me there is decent insulation.
>
>
>

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/6979989c-4bef-492a-8912-86b0818600f0%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

RE: [neonixie-l] Re: Linear power supplies for nixies

[Jeff Walton]

Agency approval only becomes a big deal if there is a lawsuit and the attorneys 
are trying to find negligence.  

In business purchases, many larger companies demand agency approvals by policy. 
 The company I am working with manufactures a device for field testing of 
thermal conductivity, which involves large heaters.  Selling into the European 
block requires the CE approval process, which is a self-administered and 
documented testing.  While it is demanded by many customers, the self-test and 
approval process leaves a tremendous amount of leeway and flexibility.  We do 
have CE markings.  As NeonJohn implied, there is not always a black and white 
answer but you should make the effort to eliminate known hazards.

In a legal contest, if you do something that can be shown to be a willful "bad" 
engineering practice and is found as negligence, you lose.  A clock burning up 
is probably not going to trigger a lawsuit - unless it kills someone.  At that 
point, the outcome depends on how good your legal representation is. 

Beyond the input isolation and materials used to build the clock, there 
probably isn't much to be worried about from a strictly legal standpoint.  Over 
the years, I've lost a few projects to transformer and other line-connected 
component failure and have come to love a well designed, agency-tested power 
brick on the front end of anything that stays plugged in and runs unattended. 
They aren't perfect either...

I had a small fire from a nixie clock I designed in the late 60's, which ran 
just fine for over 30 years until a cap failure in the voltage doubler caused 
overheating, followed by a short, and caught the wood/plexiglass housing on 
fire.  For some reason, the fuse did not fail soon enough.  The insurance 
company paid the claim with no problems.  Fortunately, smoke damage only and no 
one hurt.

Jeff 

-Original Message-
From: neonixie-l@googlegroups.com [mailto:neonixie-l@googlegroups.com] On 
Behalf Of NeonJohn
Sent: Friday, October 02, 2015 7:38 PM
To: neonixie-l@googlegroups.com
Subject: Re: [neonixie-l] Re: Linear power supplies for nixies



On 10/02/2015 03:07 AM, Dekatron42 wrote:
> Can anyone direct me to a document that says that it is allowed to 
> sell an electronic apparatus that uses a primary winding as a 
> secondary winding - I spent a lot of time Googling this and I can't find 
> anything.

I'm truly amazed that anyone would think that this sort of triviality would be 
written down somewhere.  Just as you wouldn't find, for example, an official 
document saying that one can use a 2n3904 as a very fast avalanche pulse 
generator. Or any of the millions of other techniques engineers use to 
accomplish the job.

If you pay close attention to the NEC, you'll see that most requirements can be 
modified or over-ridden by "good engineering judgement".  That is, a competent 
engineer can look at a specific situation, determine that the cook-book 
requirement doesn't fit and design a solution specific to the situation.

Of course, the engineer assumes liability for any subsequent malfunctions, just 
as an architect does for new building techniques.

I can assume with reasonable certainty that you don't know how the agency 
approval (UL, ETL, etc) works.  There's no massive tome on high that is 
consulted to determine if a given gadget works.

If you take your new design for a transformer-based wall-wart to ETL, they will 
consult their files to see if there is a testing procedure already on record.  
If so, you pay them about $2500 and they test your gadget against the procedure.

If your gadget covers new area, then you pay them something starting at about 
$10k for them to develop the testing procedure.  THEIR engineers use good 
engineering judgement based on experience when determining the testing 
procedure.  "Is 2500 VDC for 1 minute enough of an interwinding potential or 
should it be 4500?"  Based on their collected body of experience and data, as 
well as any applicable standards, they'll select an appropriate value.

Contrary to popular belief, at least here in the US, a product does NOT have to 
have agency approval to be marketed and used, except for a few malignant 
jurisdictions such as NYC.

At Fluxeon, we decided at start-up not to waste the money on agency approvals 
for our portable induction heaters.  We lose a sale here and there but all in 
all, that has turned out to be the correct decision.

As Chief Engineer and as a member of the Board, the onus for product safety 
falls on my shoulders.  My qualification requirements are vastly tougher than 
any agency would require.

A prime example is the output transformer.  It has about 1200 VAC on the 
primary and about 60 VAC on the other.  It is also the life safety barrier 
separating line voltage from the user.  An agency might require a safety factor 
of 5 and require a HiPot test of

Re: [neonixie-l] Re: Linear power supplies for nixies

[NeonJohn]

On 10/02/2015 03:07 AM, Dekatron42 wrote:
> Can anyone direct me to a document that says that it is allowed to sell an 
> electronic apparatus that uses a primary winding as a secondary winding - I 
> spent a lot of time Googling this and I can't find anything. 

I'm truly amazed that anyone would think that this sort of triviality
would be written down somewhere.  Just as you wouldn't find, for
example, an official document saying that one can use a 2n3904 as a very
fast avalanche pulse generator. Or any of the millions of other
techniques engineers use to accomplish the job.

If you pay close attention to the NEC, you'll see that most requirements
can be modified or over-ridden by "good engineering judgement".  That
is, a competent engineer can look at a specific situation, determine
that the cook-book requirement doesn't fit and design a solution
specific to the situation.

Of course, the engineer assumes liability for any subsequent
malfunctions, just as an architect does for new building techniques.

I can assume with reasonable certainty that you don't know how the
agency approval (UL, ETL, etc) works.  There's no massive tome on high
that is consulted to determine if a given gadget works.

If you take your new design for a transformer-based wall-wart to ETL,
they will consult their files to see if there is a testing procedure
already on record.  If so, you pay them about $2500 and they test your
gadget against the procedure.

If your gadget covers new area, then you pay them something starting at
about $10k for them to develop the testing procedure.  THEIR engineers
use good engineering judgement based on experience when determining the
testing procedure.  "Is 2500 VDC for 1 minute enough of an interwinding
potential or should it be 4500?"  Based on their collected body of
experience and data, as well as any applicable standards, they'll select
an appropriate value.

Contrary to popular belief, at least here in the US, a product does NOT
have to have agency approval to be marketed and used, except for a few
malignant jurisdictions such as NYC.

At Fluxeon, we decided at start-up not to waste the money on agency
approvals for our portable induction heaters.  We lose a sale here and
there but all in all, that has turned out to be the correct decision.

As Chief Engineer and as a member of the Board, the onus for product
safety falls on my shoulders.  My qualification requirements are vastly
tougher than any agency would require.

A prime example is the output transformer.  It has about 1200 VAC on the
primary and about 60 VAC on the other.  It is also the life safety
barrier separating line voltage from the user.  An agency might require
a safety factor of 5 and require a HiPot test of perhaps 6kVDC for a
minute.

Every transformer is tested at 8kVDC for one minute primary to
secondary.  The prototypes and random samples pulled from production are
tested at 12KV high frequency AC for 12 hours.  High frequency AC is a
much tougher test than DC because the HF generates dielectric losses and
other effects not seen with DC.


> I am also 
> concerned about safety and what an insurance company would have to say if a 
> fire breaks out and the culprit is the home built equipment which uses a 
> primary winding as a secondary winding.

I don't know where this widely believed fiction originated from but at
least in every state I've lived in, homeowner's insurance doesn't look
any further than whether arson was involved.

When I place burned after a computer monitor caught fire in the night,
the adjuster made a copy of the fire marshal’s report, cut me a check
for the policy limit, wished me good luck and left.  All over with in 30
minutes.

John


-- 
John DeArmond
Tellico Plains, Occupied TN
http://www.fluxeon.com  <-- THE source for induction heaters
http://www.neon-john.com<-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
https://www.etsy.com/shop/BarbraJoanOriginals  <-- please visit
PGP key: wwwkeys.pgp.net: BCB68D77

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/560F2381.1020001%40neon-john.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[Charles MacDonald]

On 15-10-02 03:07 AM, Dekatron42 wrote:

Can anyone direct me to a document that says that it is allowed to sell
an electronic apparatus that uses a primary winding as a secondary
winding - I spent a lot of time Googling this and I can't find anything.
I am also concerned about safety and what an insurance company would
have to say if a fire breaks out and the culprit is the home built
equipment which uses a primary winding as a secondary winding.



depends on the jurisdiction.  Generally to sell something you need it to 
pass an electrical inspection to be 100% kosher.  In fact technically 
here in Ontario, you need an inspection to be able to legally plug it in 
yourself!


That is what the  c(UL)US or C(CSA)us stickers you see on manufactured 
goods are all about.


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca  Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

--
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/560F16E4.6000700%40zeusprune.ca.
For more options, visit https://groups.google.com/d/optout.

RE: [neonixie-l] Re: Linear power supplies for nixies

[chuck richards]

 Reading your last post, I would suppose then,
that 5 volts would be considered "high tension"  :)


>
>
> Original Message 
>From: gregeb...@hotmail.com
>To: neonixie-l@googlegroups.com
>Subject: RE: [neonixie-l] Re: Linear power supplies for nixies
>Date: Fri, 2 Oct 2015 09:06:23 -0700 (PDT)
>
>>If you are going to sell finished products, your best option is to
>use an 
>>*external* agency-approved power-supply to produce ~12-18V. Laptop 
>>computers are a good example of this practice. Of course, you'll
>need an 
>>internal DC-DC converter so it's no longer a linear power supply :-(
>
>>
>>Regulations will vary by region, and there are organizations (UL,
>CSA, VDE, 
>>etc) that can certify your product. If you go that route, it's going
>to 
>>cost a lot of money and probably not worth the expense for something
>like 
>>nixie clocks. I'm certain that the transformer construction is a
>lesser 
>>issue; there are all sorts of things that affect approval.
>>
>>Another option is to do what I do:  chicken-out and make things only
>for 
>>yourself.  I take enough risks at my day-job because my employer has
>cost 
>>and schedule constraints developing their bleeding-edge products.
>When I 
>>make nixie clocks, I do it at my own leisure with no regard for
>cost, 
>>complexity, or schedule. I keep working on it until it's perfect.
>Then I 
>>plug it in for everyone to enjoy.
>>
>>BTW, at work we call 1.3 volts "high-voltage", and 1.5 volts is 
>>"extremely-high-voltage".  Nobody discusses 1.8 volts anymore
>because 
>>that's insanely too high to deal with
>>
>>-- 
>>You received this message because you are subscribed to the Google
>Groups "neonixie-l" group.
>>To unsubscribe from this group and stop receiving emails from it,
>send an email to neonixie-l+unsubscr...@googlegroups.com.
>>To post to this group, send an email to neonixie-l@googlegroups.com.
>>To view this discussion on the web, visit
>https://groups.google.com/d/msgid/neonixie-l/1f38e9e2-3bb0-47fa-a6fe-
>94abf42387a6%40googlegroups.com.
>>For more options, visit https://groups.google.com/d/optout.
>>



$4.95/mo. National Dialup, Anti-Spam, Anti-Virus, 5mb personal web space. 5x 
faster dialup for only $9.95/mo. No contracts, No fees, No Kidding! See 
http://www.All2Easy.net for more details!

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/380-22015105217383487%40all2easy.net.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[gregebert]

If you are going to sell finished products, your best option is to use an 
*external* agency-approved power-supply to produce ~12-18V. Laptop 
computers are a good example of this practice. Of course, you'll need an 
internal DC-DC converter so it's no longer a linear power supply :-( 

Regulations will vary by region, and there are organizations (UL, CSA, VDE, 
etc) that can certify your product. If you go that route, it's going to 
cost a lot of money and probably not worth the expense for something like 
nixie clocks. I'm certain that the transformer construction is a lesser 
issue; there are all sorts of things that affect approval.

Another option is to do what I do:  chicken-out and make things only for 
yourself.  I take enough risks at my day-job because my employer has cost 
and schedule constraints developing their bleeding-edge products. When I 
make nixie clocks, I do it at my own leisure with no regard for cost, 
complexity, or schedule. I keep working on it until it's perfect. Then I 
plug it in for everyone to enjoy.

BTW, at work we call 1.3 volts "high-voltage", and 1.5 volts is 
"extremely-high-voltage".  Nobody discusses 1.8 volts anymore because 
that's insanely too high to deal with

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/1f38e9e2-3bb0-47fa-a6fe-94abf42387a6%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[JohnK]

One of the 'requirements' here in Australia is/was for the primary and 
secondaries to be on separated parts of the bobbin. I haven't looked for the 
'rule', I just remember that when it was introduced the blurb with various 
electronic kits [and advertisements] highlighted the fact that the mains 
transformer met .  I prefer the split bobbin windings because they 'should' 
be safer if the transformer gets very overheated. I do not know what 
transformers are required to have the inbuilt thermal fuse.  I also do not know 
if separating the windings on the bobbin [as is done on the small transformers] 
is efficient enough to be used on larger transformers. 
There was a debate in a local electronics magazine about safety and 
transformers. It was pointed out there that toroidal transformers had a history 
of failing when hot due to mechanical pressures between the layers. I don't 
know how well-built the offending transformers were. Might have been 'cheapies' 
for an amplifier kit.

Lots of "I don't know" from me there - but it might contribute to talking 
points :-)

AND, the topic of RCDs. There are RCDs built in to mains plugs available. They 
might be good for extra safety.

One aspect of RCD useage which is often overlooked: they can shut off the power 
if there is a fire.  It can be worthwhile taking an earth/ground into "2-wire" 
equipment or installations to assist with protection against water ingress and 
fire. It is a long story, but I was in a position to analyse faults of PIR 
[passive infra red] detector installations and it is amazing what actually goes 
wrong. Plan for the worst thing to happen - it will somewhere ! 

John K
Australia
  - Original Message - 
  From: Dekatron42 
  To: neonixie-l 
  Sent: Friday, October 02, 2015 4:37 PM
  Subject: [neonixie-l] Re: Linear power supplies for nixies


  Can anyone direct me to a document that says that it is allowed to sell an 
electronic apparatus that uses a primary winding as a secondary winding - I 
spent a lot of time Googling this and I can't find anything. I am also 
concerned about safety and what an insurance company would have to say if a 
fire breaks out and the culprit is the home built equipment which uses a 
primary winding as a secondary winding.


  /Martin

  On Thursday, 1 October 2015 06:14:11 UTC+2, gregebert wrote:
I did some research on UL/CSA approved transformers, and there is a 
requirement that all windings withstand a minimum breakdown voltage, even if 
they are intended to be connected together, such as dual-primaries. Depending 
upon the VA rating and the voltage, the breakdown must be between 1050 and 4000 
V RMS according to how I read the spec (UL5058-2 / CSA C22.2 #66). The test is 
conducted between 1 winding, and all other windings and the core combined and 
at elevated temperature. There are copies of the spec online.


I knew there had to be some amount of isolation, but I did not realize it 
was that high. While I would never expose or touch anything that is supposedly 
"isolated", it does reassure me there is decent insulation.





  -- 
  You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
  To unsubscribe from this group and stop receiving emails from it, send an 
email to neonixie-l+unsubscr...@googlegroups.com.
  To post to this group, send email to neonixie-l@googlegroups.com.
  To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/a6a3a865-ae1b-4e3d-879f-e7dc87318c03%40googlegroups.com.
  For more options, visit https://groups.google.com/d/optout.

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/EFA64C2B2FEE41B59AB54B4F779BB167%40compunet4f9da9.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[Dekatron42]

Can anyone direct me to a document that says that it is allowed to sell an 
electronic apparatus that uses a primary winding as a secondary winding - I 
spent a lot of time Googling this and I can't find anything. I am also 
concerned about safety and what an insurance company would have to say if a 
fire breaks out and the culprit is the home built equipment which uses a 
primary winding as a secondary winding.

/Martin

On Thursday, 1 October 2015 06:14:11 UTC+2, gregebert wrote:
>
> I did some research on UL/CSA approved transformers, and there is a 
> requirement that all windings withstand a minimum breakdown voltage, even 
> if they are intended to be connected together, such as dual-primaries. 
> Depending upon the VA rating and the voltage, the breakdown must be between 
> 1050 and 4000 V RMS according to how I read the spec (UL5058-2 / CSA C22.2 
> #66). The test is conducted between 1 winding, and all other windings and 
> the core combined and at elevated temperature. There are copies of the spec 
> online.
>
> I knew there had to be some amount of isolation, but I did not realize it 
> was *that* high. While I would never expose or touch anything that is 
> supposedly "isolated", it does reassure me there is decent insulation.
>
>
>

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/a6a3a865-ae1b-4e3d-879f-e7dc87318c03%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Re: [neonixie-l] Re: Linear power supplies for nixies

[NeonJohn]

you are correct.  it is perfectly safe to use dual primaries (or
secondaries) for isolation.  The wire is triple-coated with enamel,
plastic and another layer of enamel.

While I have a multi-thousand dollar Topaz 10kVA Ultra-isolator on my
development bench, we require something cheaper for production testing
of our inductin heaters.  Dual primary dry type transformers fill the
bill just fine.  Each new transformer is HiPotted at 2500 volts winding
to winding for 10 minutes before being put into service.  Never had one
fail.

John


On 10/01/2015 12:14 AM, gregebert wrote:
> I did some research on UL/CSA approved transformers, and there is a 
> requirement that all windings withstand a minimum breakdown voltage, even 
> if they are intended to be connected together, such as dual-primaries. 
> Depending upon the VA rating and the voltage, the breakdown must be between 
> 1050 and 4000 V RMS according to how I read the spec (UL5058-2 / CSA C22.2 
> #66). The test is conducted between 1 winding, and all other windings and 
> the core combined and at elevated temperature. There are copies of the spec 
> online.
> 
> I knew there had to be some amount of isolation, but I did not realize it 
> was *that* high. While I would never expose or touch anything that is 
> supposedly "isolated", it does reassure me there is decent insulation.
> 
> 

-- 
John DeArmond
Tellico Plains, Occupied TN
http://www.fluxeon.com  <-- THE source for induction heaters
http://www.neon-john.com<-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
https://www.etsy.com/shop/BarbraJoanOriginals  <-- please visit
PGP key: wwwkeys.pgp.net: BCB68D77

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/560D7562.7010100%40neon-john.com.
For more options, visit https://groups.google.com/d/optout.

RE: [neonixie-l] Re: Linear power supplies for nixies

[chuck richards]

Yeah.  I just take a very simplistic view of it all.

Those guys at UL test that stuff under extremely harsh conditions.
If it does not break down and fail on those tests, it is very likely
that any of those windings can be used in any way anyone wants them to
be, as long as common sense is used as far as excessive current,
voltage,
power, and heat.

One of my rules of thumb:  If it runs hot enough that I can't
hold my hand on it indefinitely, it's running too hot.

Chuck


 Original Message 
From: gregeb...@hotmail.com
To: neonixie-l@googlegroups.com
Subject: [neonixie-l] Re: Linear power supplies for nixies
Date: Wed, 30 Sep 2015 21:14:11 -0700 (PDT)

>I did some research on UL/CSA approved transformers, and there is a 
>requirement that all windings withstand a minimum breakdown voltage,
>even 
>if they are intended to be connected together, such as
>dual-primaries. 
>Depending upon the VA rating and the voltage, the breakdown must be
>between 
>1050 and 4000 V RMS according to how I read the spec (UL5058-2 / CSA
>C22.2 
>#66). The test is conducted between 1 winding, and all other windings
>and 
>the core combined and at elevated temperature. There are copies of
>the spec 
>online.
>
>I knew there had to be some amount of isolation, but I did not
>realize it 
>was *that* high. While I would never expose or touch anything that is
>
>supposedly "isolated", it does reassure me there is decent
>insulation.
>
>
>-- 
>You received this message because you are subscribed to the Google
>Groups "neonixie-l" group.
>To unsubscribe from this group and stop receiving emails from it,
>send an email to neonixie-l+unsubscr...@googlegroups.com.
>To post to this group, send an email to neonixie-l@googlegroups.com.
>To view this discussion on the web, visit
>https://groups.google.com/d/msgid/neonixie-l/49ff59a7-f8f7-4ccc-bd7c-
>5969e6fd2514%40googlegroups.com.
>For more options, visit https://groups.google.com/d/optout.



$4.95/mo. National Dialup, Anti-Spam, Anti-Virus, 5mb personal web space. 5x 
faster dialup for only $9.95/mo. No contracts, No fees, No Kidding! See 
http://www.All2Easy.net for more details!

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/380-2201510414521890%40all2easy.net.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[gregebert]

I did some research on UL/CSA approved transformers, and there is a 
requirement that all windings withstand a minimum breakdown voltage, even 
if they are intended to be connected together, such as dual-primaries. 
Depending upon the VA rating and the voltage, the breakdown must be between 
1050 and 4000 V RMS according to how I read the spec (UL5058-2 / CSA C22.2 
#66). The test is conducted between 1 winding, and all other windings and 
the core combined and at elevated temperature. There are copies of the spec 
online.

I knew there had to be some amount of isolation, but I did not realize it 
was *that* high. While I would never expose or touch anything that is 
supposedly "isolated", it does reassure me there is decent insulation.


-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/49ff59a7-f8f7-4ccc-bd7c-5969e6fd2514%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Xformers Re: [neonixie-l] Re: Linear power supplies for nixies

[Charles MacDonald]

On 15-09-30 10:11 AM, gregebert wrote:

It's not the cost, but the availability. Ever since the demise of vacuum
tubes in the 1970's, high-ish voltage transformers have been getting
scarce.


If you are willing to PAY for them, there are reasonable units form 
folks like Hammond.  They have crept up in price, although the recent 
drop in the Canadian Dollar has probably put some downward  presure on 
the price in the States.


these guys for example 
https://www.hammfg.com/electronics/transformers/classic/261-262  cover 
off a lot of Nixie applications, using the "filament" windings for the 
digital stuff.


Hammond has been making similar units for about 70 or more years so no 
surprises, You an get them through places like Mouser or Antique 
electronics.  they make many of them in Guelph Ontario so even if they 
run low on stock the back order should be manageable.


--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca  Just Beyond the Fringe
No Microsoft Products were used in sending this e-mail.

--
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/560C8DC5.6030803%40zeusprune.ca.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[gregebert]

It's not the cost, but the availability. Ever since the demise of vacuum 
tubes in the 1970's, high-ish voltage transformers have been getting 
scarce. The only exception being transformers used in microwave ovens, 
which produce way too much voltage. I'm leery of salvaged transformers 
because they can degrade with age, and it's unlikely you will find 2 or 
more of the same item.

Hooking 2 transformers back-to-back is another method to get isolation, 
though less efficient.

As long as nothing is electrically exposed, it should be fine to use (or 
should I say, misuse) a dual-primary transformer.

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/090b7aab-a39b-4ea9-9c86-1c6984e5c65f%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

['marta_kson' via neonixie-l]

Using a double primary as a substitute for a secondary is a big no-no! You 
won't have the appropriate insulation to the mains. You will be just the 
thickness of two layers of enamel from grabbing the mains supply if any 
parts of the circuit can be touched. Scarry, isn't it?...

Compromizing safety to save on money is never an alternative. Order a 
properly made transformer with a safe insulation distance to the mains on 
the HV winding before something lethal happens...

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/6eb80cb1-9215-4fef-8c2a-3e57d183cada%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

RE: [neonixie-l] Re: Linear power supplies for nixies

[chuck richards]

MPJA has some nice dual-primary type power transformers
for very affordable prices.  An LP-430, which has 4 amp.
12-volt secondary works very nicely using one of the primaries
as a secondary, and then putting the real secondary in series
with it to add a bit more voltage.

Then, after rectification and filtering, that lashup feeds to a zener
diode shunt regulator which maintains 170 volts within a volt or so.

Since I am not much up on switching supply design, and since
I kind of like big, dumb, simple sorts of things, this
HV supply seems quite workable.  It's being tested now in a nixie
clock which is spread out on solderless boards.  It uses 6 of the 8422
tubes and it uses 6 of the 74HC160 counters.

Chuck
>
>
> Original Message 
>From: gregeb...@hotmail.com
>To: neonixie-l@googlegroups.com
>Subject: RE: [neonixie-l] Re: Linear power supplies for nixies
>Date: Sat, 26 Sep 2015 23:43:05 -0700 (PDT)
>
>>2. Instead of a voltage doubler, a 'boost' supply is another way to
>get 
>>higher anode-supply voltage. One version (hvsupply.pdf) 'adds' a few
>volts 
>>to the AC line before it's rectified, though it's not isolated. I
>use this 
>>in my big clock to get around +220VDC. The other version 
>>(neondr_pwrsupp.jpg)  accomplishes the same result, but it's
>isolated from 
>>the AC line and that's desirable for safety reasons.
>>
>>
>>
>>For the non-isolated supply (hvsupply.pdf), I used a 36 V
>transformer. 
>>There's a full-wave section for 220VDC (D4 & C4). There's also a
>half-wave 
>>doubler (D1, D2, D3, C2, and C3) that generates +440V for the
>dekatron in 
>>this particular clock. R3, R12, and R4 are important for safety
>reasons: 
>>They discharge the capacitors. The role of R12 is subtle, but if you
>study 
>>the circuit you will see the discharge path thru the transformer.
>RESD2 is 
>>one of several high-value resistors in the overall design that
>provide a DC 
>>path between all supplies to reduce ESD susceptibility while the
>clock is 
>>being built.
>>
>>The isolated supply (neondr_pwrsupp.jpg) is from the clock I'm
>currently 
>>designing. This circuit has not been tested in actual usage yet, but
>I have 
>>run quite a few simulations on it. I still need to run it with
>transformer 
>>winding resistance. The rectifier (XD101) and filter cap (C101)
>provide 
>>about +180V. This clock has fourteen IN-18 tubes, each running at
>5mA, so 
>>it's a fair amount of current.
>>
>>In order to get isolation, you need a dual-primary transformer. One
>of the 
>>primaries is connected to the AC line and supplies the energy; the
>other 
>>primary winding is used as a secondary winding. When using a
>transformer in 
>>this manner for isolation, you must be careful not to exceed the VA 
>>(volt-amps) rating and that means you must include the VA
>consumption for 
>>all secondary windings (which includes the primary winding that got 
>>re-purposed as a secondary). Assuming you use a diode-> capacitor 
>>rectifier, you will want to calculate the VA rating based on peak
>current, 
>>which is higher than the load current. If you pick a transformer
>with a VA 
>>rating that's too low, you will see more losses (heat). Some will be
>
>>I-squared-R losses in the windings, and most will probably be from
>core 
>>saturation. The easiest way to determine peak current is with a
>circuit 
>>simulation (LTspice and ngspice are excellent simulators available
>for 
>>free). Or, you can just try it out and see if the transformer gets
>warm; if 
>>it does, get a higher VA rating.
>>
>>I'll post another article about designing the correct filter cap
>value.
>>
>>-- 
>>You received this message because you are subscribed to the Google
>Groups "neonixie-l" group.
>>To unsubscribe from this group and stop receiving emails from it,
>send an email to neonixie-l+unsubscr...@googlegroups.com.
>>To post to this group, send an email to neonixie-l@googlegroups.com.
>>To view this discussion on the web, visit
>https://groups.google.com/d/msgid/neonixie-l/a7b6bab1-eb4f-4b67-b19c-
>69e5528d9f57%40googlegroups.com.
>>For more options, visit https://groups.google.com/d/optout.
>>



$4.95/mo. National Dialup, Anti-Spam, Anti-Virus, 5mb personal web space. 5x 
faster dialup for only $9.95/mo. No contracts, No fees, No Kidding! See 
http://www.All2Easy.net for more details!

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/380-22015902714274381%40all2easy.net.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[gregebert]

2. Instead of a voltage doubler, a 'boost' supply is another way to get 
higher anode-supply voltage. One version (hvsupply.pdf) 'adds' a few volts 
to the AC line before it's rectified, though it's not isolated. I use this 
in my big clock to get around +220VDC. The other version 
(neondr_pwrsupp.jpg)  accomplishes the same result, but it's isolated from 
the AC line and that's desirable for safety reasons.



For the non-isolated supply (hvsupply.pdf), I used a 36 V transformer. 
There's a full-wave section for 220VDC (D4 & C4). There's also a half-wave 
doubler (D1, D2, D3, C2, and C3) that generates +440V for the dekatron in 
this particular clock. R3, R12, and R4 are important for safety reasons: 
They discharge the capacitors. The role of R12 is subtle, but if you study 
the circuit you will see the discharge path thru the transformer. RESD2 is 
one of several high-value resistors in the overall design that provide a DC 
path between all supplies to reduce ESD susceptibility while the clock is 
being built.

The isolated supply (neondr_pwrsupp.jpg) is from the clock I'm currently 
designing. This circuit has not been tested in actual usage yet, but I have 
run quite a few simulations on it. I still need to run it with transformer 
winding resistance. The rectifier (XD101) and filter cap (C101) provide 
about +180V. This clock has fourteen IN-18 tubes, each running at 5mA, so 
it's a fair amount of current.

In order to get isolation, you need a dual-primary transformer. One of the 
primaries is connected to the AC line and supplies the energy; the other 
primary winding is used as a secondary winding. When using a transformer in 
this manner for isolation, you must be careful not to exceed the VA 
(volt-amps) rating and that means you must include the VA consumption for 
all secondary windings (which includes the primary winding that got 
re-purposed as a secondary). Assuming you use a diode-> capacitor 
rectifier, you will want to calculate the VA rating based on peak current, 
which is higher than the load current. If you pick a transformer with a VA 
rating that's too low, you will see more losses (heat). Some will be 
I-squared-R losses in the windings, and most will probably be from core 
saturation. The easiest way to determine peak current is with a circuit 
simulation (LTspice and ngspice are excellent simulators available for 
free). Or, you can just try it out and see if the transformer gets warm; if 
it does, get a higher VA rating.

I'll post another article about designing the correct filter cap value.

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/a7b6bab1-eb4f-4b67-b19c-69e5528d9f57%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

[taylorjpt]

...And I thought optimizing a switching power supply was supposed to be 
difficult!

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/4193759b-e66e-4e64-ac2b-c9950d9e0824%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[neonixie-l] Re: Linear power supplies for nixies

['Dave' via neonixie-l]

very informative, thanks.

I look forward to the next two installments!

On Thursday, September 24, 2015 at 3:52:06 PM UTC-4, gregebert wrote:
>
> [Forking a new thread from the partially-lighted nixie]
>
> I've used 3 different linear (ie non-switching) HV supplies in my clock 
> designs. I'll describe the basics of each in separate posts.
>
> #1: Voltage doubler. My first nixie clock has no transformers, so I use 
> the AC line directly (120V rms, 60Hz in USA). The real trick here is to 
> make sure the design is fail-safe. When the AC-line is rectified, it 
> produces about +170VDC. Nixie-tube datasheets, such as the Burroughs 5092, 
> specify a *minimum* anode voltage of 170, so that leaves no margin. With 
> a voltage-doubler, you get +340V and that gives plenty of margin, though at 
> the expense of more wasted energy (heat). If your tubes run at 2.2mA, 
> running at 340V instead of 170V will waste an extra 375mw per tube, or 
> 2.25W for a 6-digit clock. You will get reliable tube ionization at 340V, 
> and you will also have less variation in tube current as the tube ages, or 
> line-voltage variation. It's important to keep tube current in the correct 
> range, otherwise lifetime will suffer. To select the right anode resistor, 
>
> calculate R = (AnodeSupplyVoltage - OperatingVoltage)/(OperatingCurrent).
>
> For an IN-18, I've measured the operating voltage 137V at 5mA of current. 
> Tube-voltage does vary with current.
> In this example, R = 40.6K-ohms for a 340V anode supply.
>
> Referring to the attached schematic, the half-wave voltage doubler uses 2 
> diodes (D6+D10, and D2), and 2 capacitors (C5 and C1). On the negative 1/2 
> cycle, C5 is charged to the line-voltage. On the positive 1/2-cycle, C5's 
> voltage is "added" to the line-voltage, and you get twice the AC-input 
> voltage charging C1. There are also triplers, quadruplers, etc that can be 
> made.
>
> Safety is very important, so that's why there are so many 'extra' 
> components. Obviously fuses, and I put one on each AC line for redundancy, 
> and also in case hot/neutral get swapped. Resistors R15 and R16 are 
> actually 33 ohms each, and they have 3 functions: (1) limit inrush current 
> so the fuses dont blow when the caps are initially charged, (2) create an 
> RC low-pass filter along with C3 so that AC line-noise doesn't cause the 
> clock to "skip" time, and (3) act as redundant fuses. Hard to explain 
> without a picture of the PC board, but the fuse-clips are exposed metal and 
> it's possible a short could happen "before" the fuse. The varistor and C3 
> suppress voltage spikes, and if spikes are particularly nasty enough to 
> endanger the capacitors, the fuses will blow. C3 is rated at 1kV; C1 and C5 
> are rated at 450V.  So why are there 2 diodes (D6 + D10) ? In case 1 fails 
> as a short, it will prevent AC from causing a catastrophic failure of C5. 
> BTW, bridge rectifiers dont have this vulnerability; they simply short-out 
> when a single diode shorts-out.
>
> Unique for this clock, there's R21 to current-limit the AC line on the PCB 
> to ~120mA before it's sent to the NE2 bulbs that I use for the colons; just 
> extra paranoia in case something causes a short on the PCB. Those NE-2s 
> each have a 220K series resistor. You can see 6 anode resistors (R7-R12). 
> R3 & R4 form a voltage divider so I can get the 60Hz line-frequency 
> reference; this gets clamped by diodes D3 & D4 before it goes to the 
> 400-series logic for the clock divider. The remaining devices (D5, R2, Z1, 
> Z2, C2) provide +10VDC for the CMOS clock logic. Why 10 volts ? It's plenty 
> enough to drive the NMOS driver transistors for the nixie tubes (all 45 of 
> them because it's direct-drive), and also improves noise-margin.
>
> As I mentioned, this clock has no transformer. Part of the reason is to 
> reduce power-consumption, but also because I had this silly idea that you 
> can reliably operate CMOS devices off the AC line with sufficient 
> circuitry. But, there's no isolation, so just about anything on the PCB can 
> give you a shock.
>
>
>
>

-- 
You received this message because you are subscribed to the Google Groups 
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to neonixie-l+unsubscr...@googlegroups.com.
To post to this group, send an email to neonixie-l@googlegroups.com.
To view this discussion on the web, visit 
https://groups.google.com/d/msgid/neonixie-l/35ac895c-0a01-4c25-931d-beefba9caa8c%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.