Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Ken Strauss 
"Thermistor" is the generic name for a device that changes resistance with
temperature. I believe that they are available as both NTC and PTC
(negative/positive temperature coefficient) devices. As noted in my earlier
email with the TM symbol a "Surgistor" is a name trademarked by Stetron that
has now expired. For the gory details see
https://trademarks.justia.com/734/96/surgistor-73496193.html

> -Original Message-
> From: Gene Heskett [mailto:ghesk...@wdtv.com]
> Sent: Sunday, December 06, 2015 11:43 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Poor mans soft turnon
>
> On Sunday 06 December 2015 22:57:52 Rafael wrote:
>
> > On 12/06/2015 07:25 PM, Gene Heskett wrote:
> > > Greetings all;
> > >
> > > Before tv's lost their crt's, there was a component in the power
> > > inlet circuit that had a very high negative temp coefficient, which
> > > was used to create a high voltage drop when it was cold, which in
> > > turn forced the first few seconds of its power draw after being
> > > turned on, thru the degaussing coils wrapped around the crt in order
> > > to demagnetise it.
> > >
> > > That voltage drop heated it, and it got hot enough to get down to
> > > just a couple of ohms, which was not enough to overcome the MOV in
> > > series with the coils.  This also allowed the tv itself to be
> > > soft-started, and it worked so well that it was often the major part
> > > failure in the tv for the first 3 or 4 years.
> > >
> > > About 3 or 4 of those, wired in parallel, would also serve as an
> > > inrush limiter when I turn on the power supply for my G0704 mill.
> > > But the parts houses we had locally have all evaporated.  I just
> > > checked a couple surplus places without finding any of those
> > > critters.
> > >
> > > Does anyone have a suggestion as to where a small handfull of these
> > > could be sourced?  Usually bare, they look like a graphite quarter
> > > coin with a lead wire soldered to the middle of a silver plated dot
> > > in the middle of each face.  Usually slightly thicker than a
> > > 'merican quarter.
> >
> > I think you are looking for NTC (Negative Temperature Coefficient).
> > Search brings back numerous links to choose from. However, there are
> > better solutions but cost a bit more of course.
>
> Yes, and contrary to a previous poster, the name isn't a Surgistor, but a
> "Thermistor" for the NTC component.
>
> > Here is an excellent article/solution I found searching for "inrush
> >current limiter":
> > http://www.edn.com/design/analog/4316203/Simple-and-effective-inrush-c
> >urrent-limiter-stops-surges
> >
> Unforch, they do not seem to want to feed iceweasel the pdf.
>
> > Circuit is simple enough to implement it on a generic experimental
> > board.
>
> Left coast. I assume you are getting in practice at ducking behind
something
> solid. :)
>
> Thanks Rafael.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
>
>

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Jon Elson 
On 12/07/2015 06:11 AM, Gene Heskett wrote:
> I definitely need to restore some means of bleeding them 
> off when powered down. IIRC I saw some mini-candelabra 
> sockets at Wallies a while back so I need to get 2 of them 
> and put a lamp across each half of the supply. Its 2 in 
> series and 2 of those in parallel. You can see the jumpers 
> between the buss bars in the pix.
I would just get some vitreous enamel resistors.  They are 
not that expensive, even new.  Something like a 5 W 6 K Ohm 
resistor, Digi-Key 45F6K0E is about $1.86.

Jon

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread andy pugh 
On 7 December 2015 at 15:53, Jon Elson  wrote:
> I would just get some vitreous enamel resistors.  They are
> not that expensive, even new.

Or higher-power lower-resistance for a faster discharge.
http://www2.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyTHS50560RJ

As the capacitance and voltage rise you get to the point that the
bleed-of resistor becomes an electric heater, but I think you may be
below that point.

My mill has 6600uF at 300V, and I wanted a 10 second discharge
That means a 500R resistor,
A 500R resistor permanently across a 300V bus dissipates 180W. And
that's a pretty big resistor. Which is why, in my case, I decided to
only switch-in the resistor at power-off.

With less capacitance, and lower voltage, the power requirement falls
rapidly. (with the square of V).

120V and 3300uF comes out at a far more reasonable 14W with a 1K resistor

-- 
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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Ralph Stirling 
Haas cnc mills use a kitchen stove top heating element
for their spindle braking resistor.  The smaller diameter
elements are about 45 ohms, and the bigger ones 27 ohms.
Wattage is over a kw, as they run at 240vac.  The resistance
is a bit low for a capacitor discharge resistor, but at the
price you could stack a few in series.

Haas mounts them in a metal cage on top of the electrical
cabinet.

-- Ralph

From: andy pugh [bodge...@gmail.com]
Sent: Monday, December 07, 2015 8:13 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Poor mans soft turnon

On 7 December 2015 at 15:53, Jon Elson <el...@pico-systems.com> wrote:
> I would just get some vitreous enamel resistors.  They are
> not that expensive, even new.

Or higher-power lower-resistance for a faster discharge.
http://www2.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyTHS50560RJ

As the capacitance and voltage rise you get to the point that the
bleed-of resistor becomes an electric heater, but I think you may be
below that point.

My mill has 6600uF at 300V, and I wanted a 10 second discharge
That means a 500R resistor,
A 500R resistor permanently across a 300V bus dissipates 180W. And
that's a pretty big resistor. Which is why, in my case, I decided to
only switch-in the resistor at power-off.

With less capacitance, and lower voltage, the power requirement falls
rapidly. (with the square of V).

120V and 3300uF comes out at a far more reasonable 14W with a 1K resistor

--
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Marcus Bowman 

On 7 Dec 2015, at 03:57, Rafael wrote:

> 
> 
> On 12/06/2015 07:25 PM, Gene Heskett wrote:
>> Greetings all;
>> 
>> Before tv's lost their crt's, there was a component in the power inlet
>> circuit that had a very high negative temp coefficient, which was used
>> to create a high voltage drop when it was cold, which in turn forced the
>> first few seconds of its power draw after being turned on, thru the
>> degaussing coils wrapped around the crt in order to demagnetise it.
>> 
>> That voltage drop heated it, and it got hot enough to get down to just a
>> couple of ohms, which was not enough to overcome the MOV in series with
>> the coils.  This also allowed the tv itself to be soft-started, and it
>> worked so well that it was often the major part failure in the tv for
>> the first 3 or 4 years.
>> 
>> About 3 or 4 of those, wired in parallel, would also serve as an inrush
>> limiter when I turn on the power supply for my G0704 mill.  But the
>> parts houses we had locally have all evaporated.  I just checked a
>> couple surplus places without finding any of those critters.
>> 
>> Does anyone have a suggestion as to where a small handfull of these could
>> be sourced?  Usually bare, they look like a graphite quarter coin with a
>> lead wire soldered to the middle of a silver plated dot in the middle of
>> each face.  Usually slightly thicker than a 'merican quarter.
>> 
> 
> I think you are looking for NTC (Negative Temperature Coefficient). 
> Search brings back numerous links to choose from. However, there are 
> better solutions but cost a bit more of course.
> 
> Here is an excellent article/solution I found searching for "inrush 
> current limiter":
> http://www.edn.com/design/analog/4316203/Simple-and-effective-inrush-current-limiter-stops-surges
> 
> Circuit is simple enough to implement it on a generic experimental board.
> 
>> When I was setting up the mill, and building that supply, I had wired up
>> a 4 plex on the wall behind it, putting it by itself on a 20 amp
>> breaker.  Turning it on, trips the 20 instantly as the motor supply has
>> a huge amount of microfarads, probably in excess of 80,000 uf, mainly
>> because that was the size of the caps I could source, NOS, locally by
>> the fine old art of horse trading.
> 
> One variation of the above circuit could have a resistor/relay on the 
> large capacitors side to limit the inrush current then short the 
> resistor when they are at 70%+ voltage.
> 

That's similar to the PSU I built. It uses a pull-in relay (if that's the right 
term) which only latches once the supply has come up to voltage. The inrush 
current heats a metal-cased resistor and a thermistor senses the heat. The 
resistor limits the inrush to the capacitor. Once it has charged, the relay 
latches on. It only takes a second, but its enough to give an effective 
soft-start. The PSU runs 79volts at 40 amps, and uses two large toroidal 
transformers, powering a pair of steppers off each.  The specs are complete 
overkill. The start-up current is only the holding torque of the size 42 
steppers when the machine is stationary. The spindle motor is completely 
separate and has its own electronics and PSU, so that's not part of the 
equation. It only runs 2kW, so is not a problem. Soft-start there too, and 
electronic speed control, but a manufacturer-supplied control circuit.
 
Marcus

>> 
>> So, while it draws less than 3 amps with the spindle motor off, and could
>> reach 18 if the motor was in a LR state, but it takes a 30 amp breaker
>> to withstand the in-rush. If I could find some of these critters,
>> building them into that motor supply, I could put the 20 amp breaker
>> back in and it wouldn't be quite so ill eagle if an inspector looked it
>> over.
>> 
>> Cheers, Gene Heskett
>> 
> 
> Greetings from the left coast.
> 
> -- 
> Rafael
> 
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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 05:29:15 andy pugh wrote:

> On 7 December 2015 at 03:25, Gene Heskett  wrote:
> > About 3 or 4 of those, wired in parallel, would also serve as an
> > inrush limiter when I turn on the power supply for my G0704 mill.
>
> http://uk.rs-online.com/web/p/thermistors/2118030/
>
> (And similar)
>
> But finding one that is big enough might be harder.
>
> When I built the PSU for my milling machine I put a 100W resistor on
> the inlet line, with a relay to bypass it after a fixed time (using a
> 555 timer).
>
> By a coincidence, I was building a PSU for my lathe this weekend, and
> I have taken a different approach. The drives are Mesa 8i20, and these
> report bus voltage back to HAL. So the new PSU has the internal relays
> controlled by HAL.
> One SSR turns the power on, then another will be closed by HAL when
> the bus voltage has reached a threshold, and at that point the
> ...enable... pins will be toggled.
> The same chunk of HAL will be set up so that the PSU can't be turned
> on unless the bus voltage is <2V. This is to prevent arcing/welding of
> the contacts of a third (mechanical) relay that connects a crowbar
> resistor across the caps when the power goes off.

That was the reason for the night light lamp cobbled into mine, but its 
since burned out, probably from some rigid tapping as Jon's WM servo is 
a full 4 quadrant amplifier, lighting up that lamp well past its normal 
brightness as it reverses the spindle motor.  Those caps under the pcb 
buss bars can hold a surprising charge for an hour or more.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread andy pugh 
On 7 December 2015 at 03:25, Gene Heskett  wrote:
> About 3 or 4 of those, wired in parallel, would also serve as an inrush
> limiter when I turn on the power supply for my G0704 mill.

http://uk.rs-online.com/web/p/thermistors/2118030/

(And similar)

But finding one that is big enough might be harder.

When I built the PSU for my milling machine I put a 100W resistor on
the inlet line, with a relay to bypass it after a fixed time (using a
555 timer).

By a coincidence, I was building a PSU for my lathe this weekend, and
I have taken a different approach. The drives are Mesa 8i20, and these
report bus voltage back to HAL. So the new PSU has the internal relays
controlled by HAL.
One SSR turns the power on, then another will be closed by HAL when
the bus voltage has reached a threshold, and at that point the
...enable... pins will be toggled.
The same chunk of HAL will be set up so that the PSU can't be turned
on unless the bus voltage is <2V. This is to prevent arcing/welding of
the contacts of a third (mechanical) relay that connects a crowbar
resistor across the caps when the power goes off.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 03:24:21 Marcus Bowman wrote:

> On 7 Dec 2015, at 03:57, Rafael wrote:
> > On 12/06/2015 07:25 PM, Gene Heskett wrote:
> >> Greetings all;
> >>
> >> Before tv's lost their crt's, there was a component in the power
> >> inlet circuit that had a very high negative temp coefficient, which
> >> was used to create a high voltage drop when it was cold, which in
> >> turn forced the first few seconds of its power draw after being
> >> turned on, thru the degaussing coils wrapped around the crt in
> >> order to demagnetise it.
> >>
> >> That voltage drop heated it, and it got hot enough to get down to
> >> just a couple of ohms, which was not enough to overcome the MOV in
> >> series with the coils.  This also allowed the tv itself to be
> >> soft-started, and it worked so well that it was often the major
> >> part failure in the tv for the first 3 or 4 years.
> >>
> >> About 3 or 4 of those, wired in parallel, would also serve as an
> >> inrush limiter when I turn on the power supply for my G0704 mill. 
> >> But the parts houses we had locally have all evaporated.  I just
> >> checked a couple surplus places without finding any of those
> >> critters.
> >>
> >> Does anyone have a suggestion as to where a small handfull of these
> >> could be sourced?  Usually bare, they look like a graphite quarter
> >> coin with a lead wire soldered to the middle of a silver plated dot
> >> in the middle of each face.  Usually slightly thicker than a
> >> 'merican quarter.
> >
> > I think you are looking for NTC (Negative Temperature Coefficient).
> > Search brings back numerous links to choose from. However, there are
> > better solutions but cost a bit more of course.
> >
> > Here is an excellent article/solution I found searching for "inrush
> > current limiter":
> > http://www.edn.com/design/analog/4316203/Simple-and-effective-inrush
> >-current-limiter-stops-surges
> >
> > Circuit is simple enough to implement it on a generic experimental
> > board.
> >
> >> When I was setting up the mill, and building that supply, I had
> >> wired up a 4 plex on the wall behind it, putting it by itself on a
> >> 20 amp breaker.  Turning it on, trips the 20 instantly as the motor
> >> supply has a huge amount of microfarads, probably in excess of
> >> 80,000 uf, mainly because that was the size of the caps I could
> >> source, NOS, locally by the fine old art of horse trading.
> >
> > One variation of the above circuit could have a resistor/relay on
> > the large capacitors side to limit the inrush current then short the
> > resistor when they are at 70%+ voltage.
>
> That's similar to the PSU I built. It uses a pull-in relay (if that's
> the right term) which only latches once the supply has come up to
> voltage. The inrush current heats a metal-cased resistor and a
> thermistor senses the heat. The resistor limits the inrush to the
> capacitor. Once it has charged, the relay latches on. It only takes a
> second, but its enough to give an effective soft-start. The PSU runs
> 79volts at 40 amps, and uses two large toroidal transformers, powering
> a pair of steppers off each.  The specs are complete overkill. The
> start-up current is only the holding torque of the size 42 steppers
> when the machine is stationary. The spindle motor is completely
> separate and has its own electronics and PSU, so that's not part of
> the equation. It only runs 2kW, so is not a problem. Soft-start there
> too, and electronic speed control, but a manufacturer-supplied control
> circuit.
>
> Marcus

I did not put any cooling fans in this one, and it also warms up in use, 
but the major heat source is those 4 toroids that make up the spindle 
supply.  Those are stacks of 2 in the pix at sublink 

"GO704-pix/inside-of-electronics-box.jpg"

So while I am at it, I'll put a line powered rotron style fan in it to 
move some air around those toroids.  The stepper drivers are arranged 
such that the stepper supply fans, when they come on, are cooled by the 
outflow from the stepper psu's. Pix of that as it was being built are on 
my web page. That night light was to serve as a bleeder when it was 
powered down, but failed I assume while I was doing some rigid tapping 
as Jon's PWN Servo amplifier is a full 4 quadrant controller, and 
recovers the energy from the motor when its doing a reversal, driving 
the normal 126 volts no load voltage up to around 150 as it does the 
slowdown phase of reversing that 1HP motor. Thats at or slightly above 
the surge voltage rating of the capacitor bank hidden under the PCB bus 
bars to the right of the toroids in the above pix.

The active link is to GO704-pix, which I thought was in my sig, but its 
under 'More recent stuff is "here"' on the front page.  Now I think I 
have the link in the sig fixed. I'll revert that in a few days.  Pix of 
that shop-made cyclone dust separator are also there.  The entry line 
going in the top, projects downward to about 3" below the sides tangent 
entry.  Even the

Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread andy pugh 
On 7 December 2015 at 12:11, Gene Heskett  wrote:
> IIRC I saw some mini-candelabra sockets at Wallies a while back
> so I need to get 2 of them and put a lamp across each half of the
> supply. Its 2 in series and 2 of those in parallel.

I wonder if it would be worth using 240V lamps, just to keep the
brightness down?

Though, in the UK, you can pretty much only get LED and CF energy
saving lamps now, which are not ideal as dummy loads :-)

-- 
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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread andy pugh 
On 7 December 2015 at 11:23, Gene Heskett  wrote:
> a third (mechanical) relay that connects a crowbar
>> resistor across the caps when the power goes off.
>
> That was the reason for the night light lamp cobbled into mine, but its
> since burned out, probably from some rigid tapping as Jon's WM servo is
> a full 4 quadrant amplifier, lighting up that lamp well past its normal
> brightness as it reverses the spindle motor.

If you are using the Pico servo amp then I guess you are running from
120V power?

My caps are charged to about 320V which makes me rather wary of them,
hence the active discharging circuit.

-- 
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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 06:52:38 andy pugh wrote:

> On 7 December 2015 at 11:23, Gene Heskett  wrote:
> > a third (mechanical) relay that connects a crowbar
> >
> >> resistor across the caps when the power goes off.
> >
> > That was the reason for the night light lamp cobbled into mine, but
> > its since burned out, probably from some rigid tapping as Jon's WM
> > servo is a full 4 quadrant amplifier, lighting up that lamp well
> > past its normal brightness as it reverses the spindle motor.
>
> If you are using the Pico servo amp then I guess you are running from
> 120V power?
>
Yes, with a slight stepdown, so the rectified voltage is about 126 no 
load, 123 when the motor is at 2500 revs but not loaded.  And they can 
do serious damage to a screwdriver an hour after powerdown, so I 
definitely need to restore some means of bleeding them off when powered 
down.  IIRC I saw some mini-candelabra sockets at Wallies a while back 
so I need to get 2 of them and put a lamp across each half of the 
supply. Its 2 in series and 2 of those in parallel.  You can see the 
jumpers between the buss bars in the pix.

> My caps are charged to about 320V which makes me rather wary of them,
> hence the active discharging circuit.

Yes, thats not play voltage for sure.  Neither is mine, but I've been 
used for the discharge medium for higher voltages than that, several 
times.  Somehow, I'm still here.  Not my time I guess.  A good jolt and 
some burns can sure put you up for a month with shingles though.  That 
is definitely NOT on my list of fun experiences.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 07:19:25 andy pugh wrote:

> On 7 December 2015 at 12:11, Gene Heskett  wrote:
> > IIRC I saw some mini-candelabra sockets at Wallies a while back
> > so I need to get 2 of them and put a lamp across each half of the
> > supply. Its 2 in series and 2 of those in parallel.
>
> I wonder if it would be worth using 240V lamps, just to keep the
> brightness down?
>
240 volt lamps would be special order, probably in S-6 format on this 
side of the pond, and in my experience, not at all dependable, the very 
fine filaments are VERY easily broken by vibration even when cold. So 
thats something I'd never consider.  But a single 120 volter across each 
63 volt supply would suffice for this I believe.  And at a dull red 
glow, should last till the rapture.  We have one "nightlight" that has 2 
of those bulbs in it, in series.  They are dim, but 20 some years old. I 
use it for the off load to absorb the leakage of an X10 lamp module 
whose other load is a string of ccfl and led Christmas lights we 
rednecks never take down.  Otherwise they all flicker when they are 
supposed to be off. :(

> Though, in the UK, you can pretty much only get LED and CF energy
> saving lamps now, which are not ideal as dummy loads :-)


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 10:53:53 Jon Elson wrote:

> On 12/07/2015 06:11 AM, Gene Heskett wrote:
> > I definitely need to restore some means of bleeding them
> > off when powered down. IIRC I saw some mini-candelabra
> > sockets at Wallies a while back so I need to get 2 of them
> > and put a lamp across each half of the supply. Its 2 in
> > series and 2 of those in parallel. You can see the jumpers
> > between the buss bars in the pix.
>
> I would just get some vitreous enamel resistors.  They are
> not that expensive, even new.  Something like a 5 W 6 K Ohm
> resistor, Digi-Key 45F6K0E is about $1.86.
>
> Jon

Well, I had this crazy thought of drilling some holes above them in the 
front cover and using them for a power on indicator.  The 
mini-candelabra sockets and the lamps would cost more than the R's, but 
there would be a certain artistic "panache" to it, reminding me it 
hasn't been powered down when I turn off the lights for the night as I 
always look back to see what else besides the computer & monitor is on.  
A mental checklist as it were.  

Busy making the breadboard end keys, which at the feed rates I can use, 
takes about 20 minutes a key, and needs my presence for a couple minutes 
as the end of each is approached to make sure the cutoffs don't get 
tangled up & wreck a key.  So thats about an hours runtime to do them 3 
up in the width of ebony I have.  And I'm digging the slots with wood 
chisels as I don't have a 1/4" slot cutter.  Or a guide and stop for it.  
I'd dig them with a router, but it would take longer to make a guide 
shoe for the router than it takes to dig them by hand.  The downside of 
course is edge damage from the chisels.  One lid has them fitted & glued 
as of lights out this evening.  I can remove it from the jig & do the 
next lid tomorrow while 6 more keys are being cut.  Need 4 more, but the 
roundover has already created one scrap to save for pen making or 
whatever.

Thanks Andy.
'
Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-07 Thread Gene Heskett 
On Monday 07 December 2015 11:13:45 andy pugh wrote:

> On 7 December 2015 at 15:53, Jon Elson  wrote:
> > I would just get some vitreous enamel resistors.  They are
> > not that expensive, even new.
>
> Or higher-power lower-resistance for a faster discharge.
> http://www2.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtual
>keyTHS50560RJ
>
> As the capacitance and voltage rise you get to the point that the
> bleed-of resistor becomes an electric heater, but I think you may be
> below that point.
>
> My mill has 6600uF at 300V, and I wanted a 10 second discharge
> That means a 500R resistor,
> A 500R resistor permanently across a 300V bus dissipates 180W. And
> that's a pretty big resistor. Which is why, in my case, I decided to
> only switch-in the resistor at power-off.
>
> With less capacitance, and lower voltage, the power requirement falls
> rapidly. (with the square of V).
>
> 120V and 3300uF comes out at a far more reasonable 14W with a 1K
> resistor

I have nominally 63 volts and nearly 100k u-f to discharge.  I have a 
similar getup on the lathe at slightly lower total voltage (107) & quite 
a bit less u-f, and its about 15 minutes to screwdriver safe.  3 or 4 
minutes until the bulb is dark.

This may need the switched load if you want to work in it without going 
in and re-boreing an empty coffee cup & refilling it for a time 
killer. :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Some mill pix are at:
Genes Web page 

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[Emc-users] Poor mans soft turnon

2015-12-06 Thread Gene Heskett 
Greetings all;

Before tv's lost their crt's, there was a component in the power inlet 
circuit that had a very high negative temp coefficient, which was used 
to create a high voltage drop when it was cold, which in turn forced the 
first few seconds of its power draw after being turned on, thru the 
degaussing coils wrapped around the crt in order to demagnetise it.

That voltage drop heated it, and it got hot enough to get down to just a 
couple of ohms, which was not enough to overcome the MOV in series with 
the coils.  This also allowed the tv itself to be soft-started, and it 
worked so well that it was often the major part failure in the tv for 
the first 3 or 4 years.

About 3 or 4 of those, wired in parallel, would also serve as an inrush 
limiter when I turn on the power supply for my G0704 mill.  But the 
parts houses we had locally have all evaporated.  I just checked a 
couple surplus places without finding any of those critters.

Does anyone have a suggestion as to where a small handfull of these could 
be sourced?  Usually bare, they look like a graphite quarter coin with a 
lead wire soldered to the middle of a silver plated dot in the middle of 
each face.  Usually slightly thicker than a 'merican quarter.

When I was setting up the mill, and building that supply, I had wired up 
a 4 plex on the wall behind it, putting it by itself on a 20 amp 
breaker.  Turning it on, trips the 20 instantly as the motor supply has 
a huge amount of microfarads, probably in excess of 80,000 uf, mainly 
because that was the size of the caps I could source, NOS, locally by 
the fine old art of horse trading.

So, while it draws less than 3 amps with the spindle motor off, and could 
reach 18 if the motor was in a LR state, but it takes a 30 amp breaker 
to withstand the in-rush. If I could find some of these critters, 
building them into that motor supply, I could put the 20 amp breaker 
back in and it wouldn't be quite so ill eagle if an inspector looked it 
over.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Gene Heskett 
On Sunday 06 December 2015 22:55:27 Ken Strauss wrote:

> I assume that you mean a Surgistor(TM). You'll find them for very high
> prices on eBay (the one currently listed is $25!). Google shows
> several places that claim to have them.
>
Sound like they renamed it so they could charge antique prices for it. 
They were just a couple bucks back in 1985.

I'll google the net for the new name.

Thanks Ken.

> > -Original Message-
> > From: Gene Heskett [mailto:ghesk...@wdtv.com]
> > Sent: Sunday, December 06, 2015 10:26 PM
> > To: Enhanced Machine Controller (EMC)
> > Subject: [Emc-users] Poor mans soft turnon
> >
> > Greetings all;
> >
> > Before tv's lost their crt's, there was a component in the power
> > inlet
>
> circuit
>
> > that had a very high negative temp coefficient, which was used to
> > create a high voltage drop when it was cold, which in turn forced
> > the first few
>
> seconds
>
> > of its power draw after being turned on, thru the degaussing coils
> > wrapped around the crt in order to demagnetise it.
> >
> > That voltage drop heated it, and it got hot enough to get down to
> > just a
>
> couple
>
> > of ohms, which was not enough to overcome the MOV in series with the
>
> coils.
>
> > This also allowed the tv itself to be soft-started, and it worked so
> > well
>
> that it
>
> > was often the major part failure in the tv for the first 3 or 4
> > years.
> >
> > About 3 or 4 of those, wired in parallel, would also serve as an
> > inrush
>
> limiter
>
> > when I turn on the power supply for my G0704 mill.  But the parts
> > houses
>
> we
>
> > had locally have all evaporated.  I just checked a couple surplus
> > places
>
> without
>
> > finding any of those critters.
> >
> > Does anyone have a suggestion as to where a small handfull of these
> > could
>
> be
>
> > sourced?  Usually bare, they look like a graphite quarter coin with
> > a lead
>
> wire
>
> > soldered to the middle of a silver plated dot in the middle of each
> > face. Usually slightly thicker than a 'merican quarter.
> >
> > When I was setting up the mill, and building that supply, I had
> > wired up a
>
> 4
>
> > plex on the wall behind it, putting it by itself on a 20 amp
> > breaker.
>
> Turning it
>
> > on, trips the 20 instantly as the motor supply has a huge amount of
> > microfarads, probably in excess of 80,000 uf, mainly because that
> > was the
>
> size
>
> > of the caps I could source, NOS, locally by the fine old art of
> > horse
>
> trading.
>
> > So, while it draws less than 3 amps with the spindle motor off, and
> > could
>
> reach
>
> > 18 if the motor was in a LR state, but it takes a 30 amp breaker to
>
> withstand
>
> > the in-rush. If I could find some of these critters, building them
> > into
>
> that motor
>
> > supply, I could put the 20 amp breaker back in and it wouldn't be
> > quite so
>
> ill
>
> > eagle if an inspector looked it over.
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > Genes Web page <http://geneslinuxbox.net:6309/gene>
>
> --
>-- --
>
> > Go from Idea to Many App Stores Faster with Intel(R) XDK Give your
> > users amazing mobile app experiences with Intel(R) XDK.
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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Jon Elson 
On 12/06/2015 10:42 PM, Gene Heskett wrote:
> On Sunday 06 December 2015 22:57:52 Rafael wrote:
>
>> On 12/06/2015 07:25 PM, Gene Heskett wrote:
>>> Greetings all;
>>>
>>> Before tv's lost their crt's, there was a component in the power
>>> inlet circuit that had a very high negative temp coefficient, which
>>> was used to create a high voltage drop when it was cold, which in
>>> turn forced the first few seconds of its power draw after being
>>> turned on, thru the degaussing coils wrapped around the crt in order
>>> to demagnetise it.
>>>
>>> That voltage drop heated it, and it got hot enough to get down to
>>> just a couple of ohms, which was not enough to overcome the MOV in
>>> series with the coils.  This also allowed the tv itself to be
>>> soft-started, and it worked so well that it was often the major part
>>> failure in the tv for the first 3 or 4 years.
>>>
>>> About 3 or 4 of those, wired in parallel, would also serve as an
>>> inrush limiter when I turn on the power supply for my G0704 mill.
>>> But the parts houses we had locally have all evaporated.  I just
>>> checked a couple surplus places without finding any of those
>>> critters.
>>>
>>> Does anyone have a suggestion as to where a small handfull of these
>>> could be sourced?  Usually bare, they look like a graphite quarter
>>> coin with a lead wire soldered to the middle of a silver plated dot
>>> in the middle of each face.  Usually slightly thicker than a
>>> 'merican quarter.
>> I think you are looking for NTC (Negative Temperature Coefficient).
>> Search brings back numerous links to choose from. However, there are
>> better solutions but cost a bit more of course.
> Yes, and contrary to a previous poster, the name isn't a Surgistor, but
> a "Thermistor" for the NTC component.
Digi-Key has them, but maybe not in a current you want.
http://www.digikey.com/product-search/en/circuit-protection/inrush-current-limiters-icl/656273?k=ntc%20thermistor

Here's more :
http://www.digikey.com/product-search/en/sensors-transducers/thermistors-ntc/1966148?k=ntc%20thermistor
>
Jon

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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Rafael 


On 12/06/2015 07:25 PM, Gene Heskett wrote:
> Greetings all;
>
> Before tv's lost their crt's, there was a component in the power inlet
> circuit that had a very high negative temp coefficient, which was used
> to create a high voltage drop when it was cold, which in turn forced the
> first few seconds of its power draw after being turned on, thru the
> degaussing coils wrapped around the crt in order to demagnetise it.
>
> That voltage drop heated it, and it got hot enough to get down to just a
> couple of ohms, which was not enough to overcome the MOV in series with
> the coils.  This also allowed the tv itself to be soft-started, and it
> worked so well that it was often the major part failure in the tv for
> the first 3 or 4 years.
>
> About 3 or 4 of those, wired in parallel, would also serve as an inrush
> limiter when I turn on the power supply for my G0704 mill.  But the
> parts houses we had locally have all evaporated.  I just checked a
> couple surplus places without finding any of those critters.
>
> Does anyone have a suggestion as to where a small handfull of these could
> be sourced?  Usually bare, they look like a graphite quarter coin with a
> lead wire soldered to the middle of a silver plated dot in the middle of
> each face.  Usually slightly thicker than a 'merican quarter.
>

I think you are looking for NTC (Negative Temperature Coefficient). 
Search brings back numerous links to choose from. However, there are 
better solutions but cost a bit more of course.

Here is an excellent article/solution I found searching for "inrush 
current limiter":
http://www.edn.com/design/analog/4316203/Simple-and-effective-inrush-current-limiter-stops-surges

Circuit is simple enough to implement it on a generic experimental board.

> When I was setting up the mill, and building that supply, I had wired up
> a 4 plex on the wall behind it, putting it by itself on a 20 amp
> breaker.  Turning it on, trips the 20 instantly as the motor supply has
> a huge amount of microfarads, probably in excess of 80,000 uf, mainly
> because that was the size of the caps I could source, NOS, locally by
> the fine old art of horse trading.

One variation of the above circuit could have a resistor/relay on the 
large capacitors side to limit the inrush current then short the 
resistor when they are at 70%+ voltage.

>
> So, while it draws less than 3 amps with the spindle motor off, and could
> reach 18 if the motor was in a LR state, but it takes a 30 amp breaker
> to withstand the in-rush. If I could find some of these critters,
> building them into that motor supply, I could put the 20 amp breaker
> back in and it wouldn't be quite so ill eagle if an inspector looked it
> over.
>
> Cheers, Gene Heskett
>

Greetings from the left coast.

-- 
Rafael

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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Ken Strauss 
I assume that you mean a Surgistor(TM). You'll find them for very high
prices on eBay (the one currently listed is $25!). Google shows several
places that claim to have them.


> -Original Message-
> From: Gene Heskett [mailto:ghesk...@wdtv.com]
> Sent: Sunday, December 06, 2015 10:26 PM
> To: Enhanced Machine Controller (EMC)
> Subject: [Emc-users] Poor mans soft turnon
>
> Greetings all;
>
> Before tv's lost their crt's, there was a component in the power inlet
circuit
> that had a very high negative temp coefficient, which was used to create a
> high voltage drop when it was cold, which in turn forced the first few
seconds
> of its power draw after being turned on, thru the degaussing coils wrapped
> around the crt in order to demagnetise it.
>
> That voltage drop heated it, and it got hot enough to get down to just a
couple
> of ohms, which was not enough to overcome the MOV in series with the
coils.
> This also allowed the tv itself to be soft-started, and it worked so well
that it
> was often the major part failure in the tv for the first 3 or 4 years.
>
> About 3 or 4 of those, wired in parallel, would also serve as an inrush
limiter
> when I turn on the power supply for my G0704 mill.  But the parts houses
we
> had locally have all evaporated.  I just checked a couple surplus places
without
> finding any of those critters.
>
> Does anyone have a suggestion as to where a small handfull of these could
be
> sourced?  Usually bare, they look like a graphite quarter coin with a lead
wire
> soldered to the middle of a silver plated dot in the middle of each face.
> Usually slightly thicker than a 'merican quarter.
>
> When I was setting up the mill, and building that supply, I had wired up a
4
> plex on the wall behind it, putting it by itself on a 20 amp breaker.
Turning it
> on, trips the 20 instantly as the motor supply has a huge amount of
> microfarads, probably in excess of 80,000 uf, mainly because that was the
size
> of the caps I could source, NOS, locally by the fine old art of horse
trading.
>
> So, while it draws less than 3 amps with the spindle motor off, and could
reach
> 18 if the motor was in a LR state, but it takes a 30 amp breaker to
withstand
> the in-rush. If I could find some of these critters, building them into
that motor
> supply, I could put the 20 amp breaker back in and it wouldn't be quite so
ill
> eagle if an inspector looked it over.
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
>
>

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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Gene Heskett 
On Sunday 06 December 2015 22:57:52 Rafael wrote:

> On 12/06/2015 07:25 PM, Gene Heskett wrote:
> > Greetings all;
> >
> > Before tv's lost their crt's, there was a component in the power
> > inlet circuit that had a very high negative temp coefficient, which
> > was used to create a high voltage drop when it was cold, which in
> > turn forced the first few seconds of its power draw after being
> > turned on, thru the degaussing coils wrapped around the crt in order
> > to demagnetise it.
> >
> > That voltage drop heated it, and it got hot enough to get down to
> > just a couple of ohms, which was not enough to overcome the MOV in
> > series with the coils.  This also allowed the tv itself to be
> > soft-started, and it worked so well that it was often the major part
> > failure in the tv for the first 3 or 4 years.
> >
> > About 3 or 4 of those, wired in parallel, would also serve as an
> > inrush limiter when I turn on the power supply for my G0704 mill. 
> > But the parts houses we had locally have all evaporated.  I just
> > checked a couple surplus places without finding any of those
> > critters.
> >
> > Does anyone have a suggestion as to where a small handfull of these
> > could be sourced?  Usually bare, they look like a graphite quarter
> > coin with a lead wire soldered to the middle of a silver plated dot
> > in the middle of each face.  Usually slightly thicker than a
> > 'merican quarter.
>
> I think you are looking for NTC (Negative Temperature Coefficient).
> Search brings back numerous links to choose from. However, there are
> better solutions but cost a bit more of course.

Yes, and contrary to a previous poster, the name isn't a Surgistor, but 
a "Thermistor" for the NTC component.

> Here is an excellent article/solution I found searching for "inrush
> current limiter":
> http://www.edn.com/design/analog/4316203/Simple-and-effective-inrush-c
>urrent-limiter-stops-surges
>
Unforch, they do not seem to want to feed iceweasel the pdf.

> Circuit is simple enough to implement it on a generic experimental
> board.

Left coast. I assume you are getting in practice at ducking behind 
something solid. :)

Thanks Rafael.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Genes Web page 

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Re: [Emc-users] Poor mans soft turnon

2015-12-06 Thread Gene Heskett 
On Monday 07 December 2015 00:01:20 Jon Elson wrote:

> On 12/06/2015 10:42 PM, Gene Heskett wrote:
> > On Sunday 06 December 2015 22:57:52 Rafael wrote:
> >> On 12/06/2015 07:25 PM, Gene Heskett wrote:
> >>> Greetings all;
> >>>
> >>> Before tv's lost their crt's, there was a component in the power
> >>> inlet circuit that had a very high negative temp coefficient,
> >>> which was used to create a high voltage drop when it was cold,
> >>> which in turn forced the first few seconds of its power draw after
> >>> being turned on, thru the degaussing coils wrapped around the crt
> >>> in order to demagnetise it.
> >>>
> >>> That voltage drop heated it, and it got hot enough to get down to
> >>> just a couple of ohms, which was not enough to overcome the MOV in
> >>> series with the coils.  This also allowed the tv itself to be
> >>> soft-started, and it worked so well that it was often the major
> >>> part failure in the tv for the first 3 or 4 years.
> >>>
> >>> About 3 or 4 of those, wired in parallel, would also serve as an
> >>> inrush limiter when I turn on the power supply for my G0704 mill.
> >>> But the parts houses we had locally have all evaporated.  I just
> >>> checked a couple surplus places without finding any of those
> >>> critters.
> >>>
> >>> Does anyone have a suggestion as to where a small handfull of
> >>> these could be sourced?  Usually bare, they look like a graphite
> >>> quarter coin with a lead wire soldered to the middle of a silver
> >>> plated dot in the middle of each face.  Usually slightly thicker
> >>> than a 'merican quarter.
> >>
> >> I think you are looking for NTC (Negative Temperature Coefficient).
> >> Search brings back numerous links to choose from. However, there
> >> are better solutions but cost a bit more of course.
> >
> > Yes, and contrary to a previous poster, the name isn't a Surgistor,
> > but a "Thermistor" for the NTC component.
>
> Digi-Key has them, but maybe not in a current you want.
> http://www.digikey.com/product-search/en/circuit-protection/inrush-cur
>rent-limiters-icl/656273?k=ntc%20thermistor
>
> Here's more :
> http://www.digikey.com/product-search/en/sensors-transducers/thermisto
>rs-ntc/1966148?k=ntc%20thermistor
>
> Jon

Now that I've thought about it, since the loading is highly dependent on 
the spindle motors loading,so the draw can run from about 2.75 amps to 
perhaps 18 or so for locked rotor, at least a 6/1 ratio, the more I 
realize that is the wrong approach.  Far more consistent would be a flat 
time delay, operated by one of the other supplies in that box, rigged to 
put a 8 ohm 20 watt R in series with the line in, for perhaps 1/2 second 
after power on.  That should cut the inrush by at least 50% of its peak 
amperage.  Most time delays I can find are more than 1 second, least I 
found tonight was 6 seconds, and I don't have enough of those 8 ohm 20 
watters to last that long.

I may, when things slow a bit, see about building my own time delay in 
hal.  Maybe even tie it to the charge pump so I can control the power to 
the mill with LCNC.  Use a time delay hal module to gate the charge 
pump, first to power it up, then half a second later to close the relay 
and short the current limiter.  The switched charge pump is controlling 
the vacuum cleaner (older Bucket Max) just fine.  And I still have quite 
a few pins on the 2nd BoB to do that with yet.

Thanks Jon.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

--
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Give your users amazing mobile app experiences with Intel(R) XDK.
Use one codebase in this all-in-one HTML5 development environment.
Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs.
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