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PICList Thread
'[EE] Neon lamps'
2007\09\27@155717 by David VanHorn

picon face
Like the NE-51 and such..

I'm building a blinky box for a friend, powered by 12 9V batteries in
series, and have hit a bit of a snag.

When first powered up, the lamps flash as you'd expect, using 10M and
22M resistors with 0.1uF 250V caps.  But after running for a week or
two, the lamps glow softly and don't blink.  Touching the lamps,
turning on the room lights, or even bringing a finger near them will
cause a blink when they are glowing softly but then they return to
glowing.

Am I running too low a resistance value?? Is there something wrong
with my neons?   It's probably something that was widely known 30
years ago, but I haven't had any luck gargoyling for an answer.

2007\09\27@161416 by Thomas C. Sefranek

face picon face
Voltage is too high!
Google the ignition voltage of NE-2s.

 *
 |  __O    Thomas C. Sefranek  spam_OUTWA1RHPTakeThisOuTspamARRL.NET
 |_-\<,_   Amateur Radio Operator: WA1RHP
 (*)/ (*)  Bicycle mobile on 145.41MHz PL74.4

ARRL Instructor, Technical Specialist, VE Contact.
hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

{Original Message removed}

2007\09\27@161458 by Peter P.

picon face
David VanHorn <microbrix <at> gmail.com> writes:

Neons die if they run directly off a cap. Replace them and put a reasonable
resistor in series with each to limit the current. I'd try 1K 1W for about 100mA
inrush assuming Vign=140V and Vburn=70V. This is more than 50 times their
operating current afaik but it might keep them alive longer. In general you
should never connect something with negative resistance directly to a voltage
source (like a charged cap).

Peter P.




2007\09\28@004328 by David VanHorn

picon face
On 9/27/07, Thomas C. Sefranek <.....tcsKILLspamspam@spam@cmcorp.com> wrote:
> Voltage is too high!
> Google the ignition voltage of NE-2s.


How would it ever get too high?
The ckt is cap in parallel with the neon, and there's a 10 or 22 MEG
resistor between the cap/neon and the battery.  Voltage ramps up to
about 55-60V, then dumps down.
But when they get in this half-on mode, they sit there with 55-60V on them.
Hard to measure, the scope probe capacitance affects things.

2007\09\28@004501 by David VanHorn

picon face
On 9/27/07, Peter P. <plpeter2006spamKILLspamyahoo.com> wrote:
> David VanHorn <microbrix <at> gmail.com> writes:
>
> Neons die if they run directly off a cap. Replace them and put a reasonable
> resistor in series with each to limit the current. I'd try 1K 1W for about 100mA
> inrush assuming Vign=140V and Vburn=70V.

I've NEVER seen the circuit done with a second resistor like that.


> This is more than 50 times their
> operating current afaik but it might keep them alive longer. In general you
> should never connect something with negative resistance directly to a voltage
> source (like a charged cap).

That's the whole point of a relaxation oscillator, isn't it?
I've done it with tunnel diodes, UJTs, and neons before.

2007\09\28@004549 by

picon face
you might try smaller resistorsi can remember building one with 16  ne-2
and seems like i used 4.7 meg resistoes and 0.5 caps.,
as far as i can remember the resistors & neons are in series across the
power supply
and the caps are daisy chained between the neons..
hope this helps.
de Jx
                             
                               

{Quote hidden}

> --

2007\09\28@013643 by William \Chops\ Westfield

face picon face

On Sep 27, 2007, at 1:12 PM, Thomas C. Sefranek wrote:

> Voltage is too high!

That's my gut feel too.  90V was "typical" for such circuits
(built one in HS, but it got stolen before it had been on for
weeks.)  IIRC, the bulbs would light at about 70V; try connecting
to an assorted string of batteries through a 10k resistor, and
stop when you get a solid glow.

In the old days, you could sort of count on the high internal
resistance of Zn/Cl 90V dry cells to keep them relatively safe.
These days, I imagine a sting of 12 alkaline 9V batteries could
deliver quite a shock!

BillW

2007\09\28@073608 by Thomas C. Sefranek

face picon face
With the voltage too high, the ballast resistor is too low to cause
extinction.
The lamp will "simmer" in the sustain region, hence the low glow.
True, I believe you can have any voltage, but you must limit the current.

Think of it this way, the capacitor is the energy storage for the main
flash.  The lamp just needs an ignition pulse, much like a xenon lamp.


 *
 |  __O    Thomas C. Sefranek  WA1RHPspamspam_OUTARRL.NET
 |_-\<,_   Amateur Radio Operator: WA1RHP
 (*)/ (*)  Bicycle mobile on 145.41MHz PL74.4

ARRL Instructor, Technical Specialist, VE Contact.
hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

{Original Message removed}

2007\09\28@074326 by Thomas C. Sefranek

face picon face
I think I would again mention the xenon flash lamp example.
There is NO need to ballast the flash lamp IF you have considered the
watt/seconds you will be dissipating in the lamp.
With enough capacitance/voltage, you can affect the life of the lamp.

How many have seen appliances with flickering or dead neon lamps?
Yes, they have a limited lifetime, even when run at the recommended current.

 *
 |  __O    Thomas C. Sefranek  @spam@WA1RHPKILLspamspamARRL.NET
 |_-\<,_   Amateur Radio Operator: WA1RHP
 (*)/ (*)  Bicycle mobile on 145.41MHz PL74.4

ARRL Instructor, Technical Specialist, VE Contact.
hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

{Original Message removed}

2007\09\28@083453 by David VanHorn

picon face
> In the old days, you could sort of count on the high internal
> resistance of Zn/Cl 90V dry cells to keep them relatively safe.
> These days, I imagine a sting of 12 alkaline 9V batteries could
> deliver quite a shock!

Yes it would, I've tried shorting it momentarily, nice fat arc.
The string of 9V batteries is less expensive (at batteries plus) than
the equivalent HV battery, and I figured for the future that the 9V
answer would be more survivable.

2007\09\28@085835 by Alan B. Pearce

face picon face
>I think I would again mention the xenon flash lamp example.
>There is NO need to ballast the flash lamp IF you have considered
>the watt/seconds you will be dissipating in the lamp.
>With enough capacitance/voltage, you can affect the life of the lamp.

I a number of cases that I am aware of with photographic flash lamps, the
discharge current is limited by the wiring from the capacitor to the lamp
being of sufficient length to have enough microhenries to limit dv/dt, so
the lamp doesn't act as a total short circuit on the capacitor. Such wiring
was not shown explicitly on the schematic as an inductor, just as a
connection.

2007\09\28@095509 by David VanHorn

picon face
ourworld.compuserve.com/homepages/Bill_Bowden/page7.htm#neon.gif

The circuit I'm using is the first one, on the left, just feeding it a
higher voltage is all.
I'm using 10-20M and 0.1uF, but the RC values aren't critical.

2007\09\28@103826 by David VanHorn

picon face
On 9/28/07, Thomas C. Sefranek <KILLspamtcsKILLspamspamcmcorp.com> wrote:
> With the voltage too high, the ballast resistor is too low to cause
> extinction.
> The lamp will "simmer" in the sustain region, hence the low glow.
> True, I believe you can have any voltage, but you must limit the current.

So I tried varying the operating voltage.
12 batteries is what I've been using, the old lamps glow weakly, new
ones flash nicely.
11 batteries, new lamps flash very slowly, old lamps glow weaker.
10 batteries, only one or two of the new lamps flash, old lamps are off.

Makes sense to me that the voltage would change things a bit,
interesting that 90V dosen't seem to drive things very well though..
Maybe I need to use 1M and 90V instead of 10M and 110V?

> Think of it this way, the capacitor is the energy storage for the main
> flash.  The lamp just needs an ignition pulse, much like a xenon lamp.

I understand what you mean, but I have never, EVER seen one of these
circuits use a limiting resistor in series with the lamp. I think the
lamp itself limits the current significantly, I may get motivated
enough to stick a 1 ohm in there and measure it.  Or I suppose I could
measure the optical pulse width as well.

2007\09\28@115226 by Bob Blick

face picon face

--- David VanHorn <RemoveMEmicrobrixTakeThisOuTspamgmail.com> wrote:

> So I tried varying the operating voltage.
> 12 batteries is what I've been using, the old lamps
> glow weakly, new
> ones flash nicely.
> 11 batteries, new lamps flash very slowly, old lamps
> glow weaker.
> 10 batteries, only one or two of the new lamps
> flash, old lamps are off.

To me it seems clear that the old bulbs are worn out,
albeit prematurely.

> I have never, EVER
> seen one of these
> circuits use a limiting resistor in series with the
> lamp.

Until recently, all the circuits I have ever seen(and
built) have ALWAYS had limiting resistors. I think
this is the reason for the premature wear on the
bulbs.

Cheerful regards,

Bob

2007\09\28@121046 by Bob Blick

face picon face
--- "Thomas C. Sefranek" <spamBeGonetcsspamBeGonespamcmcorp.com> wrote:

> How many have seen appliances with flickering or
> dead neon lamps?

That's the (almost only) advantage to 240 volts.
Fluorescent lamps and neon bulbs last a lot longer.
But incandescents burn out a lot quicker, the thin
filaments just can't take as much punishment.

Cheerful regards,

Bob

2007\09\28@144549 by David VanHorn

picon face
>
> Until recently, all the circuits I have ever seen(and
> built) have ALWAYS had limiting resistors. I think
> this is the reason for the premature wear on the
> bulbs.


Limiting resistors when used with an HV power supply, or battery
directly, but I've never seen one between the cap and neon in a
flasher that gets roughly 10 microamps average current from the
battery.

Measuring it, I inserted a 10 ohm series resistor on the ground side
of the lamp, and I see about 0.9V peak, with a risetime of 25uS and a
fall slightly slower.

Of course if it is the peak current, then that begs the question of
what SHOULD it be limited to? I haven't seen a spec sheet in a long
time on one of these.
Seems 0.5 - 3mA is typical, so assuming 1mA then 68k seems reasonable.

I'll try it, but man in 40 years I have never seen a neon flasher
schematic with more than ONE resistor!

2007\09\28@150837 by David VanHorn

picon face
Interesting!

The original neon, with no current limiting resistor, has dropped to
less than half the discharge current that I originally measured.

68K meanwhile gives me a much broader discharge pulse, limited to
roughly 0.5mA. 34V peak across the resistor, so the lamp has roughly
the same impedance at this current.

There are also some interesting aspects to the discharge, I can see
current building up slowly, at very low levels, just prior to
discharge.  Hmm.. :)

2007\09\28@190214 by Peter P.

picon face
David VanHorn <microbrix <at> gmail.com> writes:

> I've NEVER seen the circuit done with a second resistor like that.

The indicator neons are delicate and their electrode spacing is critical for
uniform lighting. Repeated high current discharges will plate a whisker or blow
a small raw edged hole in an electrode that will change the ignition voltage. I
am willing to bet a small virtual sum that the neons are not burning faintly but
oscillating at high frequency because of that. Also some indicators have a
coating on the electrodes. If this was blown off it may cause what you are
seeing. Ditto if the gas pressure changed due to desorbed stuff (like plating)
from the tortured electrodes.

I think that the reason you never saw a circuit like that was, that those
circuits with the proper resistors *never* fail (within reason).

1K in series should make almost no difference in the perceived light pulses.

Unlike flash bulbs and surge arrestors the neon indicators are very delicate. I
cannot find a max current rating but I think that you can say that running 100
times stated current life will be shortened 100 times. From 10,000 hours to,
say, 100. According to datasheets the life end occurs when the ignition voltage
reaches the line voltage (i.e. it increases during life). If you are using a 110V
circuit without a voltage doubler rectifier this may be happening prematurely in
your circuit (they say use minimum 135V as ignition voltage). They also say that
ign. voltage in light is higher than in darkness. That seems to contradict what
I know about how these tubes work (they need light to get started).

Here is a contemporary circuit that shows no current paths that have no
resistors in them:

 http://www.decodesystems.com/ge-glow-lamp-6162m.gif

Please refer to a datasheet (f.ex. from CML) to see ignition voltages etc.

Peter P.


2007\09\29@110310 by David VanHorn

picon face
> I think that the reason you never saw a circuit like that was, that those
> circuits with the proper resistors *never* fail (within reason).

I don't follow.. What I'm saying is that every published circuit I've
seen for these has not had a resistor in series with the lamp.

> 1K in series should make almost no difference in the perceived light pulses.

Not much in the discharge current either.  It took 33k-68k to get the
current down into the right range.

I'm convinced now that the resistors in series with the lamp are
needed, I measured severe degradation on my test lamp, current levels
falling by more than 50%, in only about an hour's operation at a few
PPS.


> Unlike flash bulbs and surge arrestors the neon indicators are very delicate. I
> cannot find a max current rating but I think that you can say that running 100
> times stated current life will be shortened 100 times. From 10,000 hours to,
> say, 100. According to datasheets the life end occurs when the ignition voltage
> reaches the line voltage (i.e. it increases during life). If you are using a 110V
> circuit without a voltage doubler rectifier this may be happening prematurely in
> your circuit (they say use minimum 135V as ignition voltage).

??  These light at 55-60V, and are powered from batteries. 12x9V in this case.

> They also say that
> ign. voltage in light is higher than in darkness. That seems to contradict what
> I know about how these tubes work (they need light to get started).

I think that's wrong. Light helps, the light knocks electrons loose
from the metal.


>
> Here is a contemporary circuit that shows no current paths that have no
> resistors in them:
>
>   http://www.decodesystems.com/ge-glow-lamp-6162m.gif

True, but in this case they are picking off the signal to do somethig with it.
It's not obvious that the resistor is ALSO preventing the lamp from
being destroyed.  The novelty flasher circuits I've seen always had
one resistor, one cap, and one lamp.  (I'm just repeating that 50
times. )

> Please refer to a datasheet (f.ex. from CML) to see ignition voltages etc.

If only.. I have NO idea who made these, or if they are even in
business anymore.
I just measured the ign voltage myself, and I'm using the low end of
the 0.5 - 3mA current ranges I've seen on other "neon lamp" data
sheets, like NE-51 and NE-52.

2007\09\29@133851 by Brooke Clarke

flavicon
face
Hi David:

What you are seeing is the neon lamp acting as a voltage regulator.  I.e. after
it fires there's still enough voltage to keep it alive.

You haven't mentioned what you're using for the capacitor.  Is it a 1950
vintage part or a modern low loss cap?  If the latter then there's not enough
leakage current in the cap to pull the voltage down below the extinction voltage.

Just add a shunt resistor across the cap.
--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam

2007\09\29@144223 by Peter P.

picon face
David VanHorn <microbrix <at> gmail.com> writes:

> True, but in this case they are picking off the signal to do somethig with
> it.
> It's not obvious that the resistor is ALSO preventing the lamp from
> being destroyed.  The novelty flasher circuits I've seen always had
> one resistor, one cap, and one lamp.  (I'm just repeating that 50
> times. )

It depends a lot on the lamp and the make. Literature that uses several talks
about 'aging' them. There are also lamps designed for gradual light-up, they
were used as bar graph indicators. Abrupt on and uniform lighting depends on
relatively large radius parallel or concentric electrodes at very exact spacing
to each other and on a certain pressure and gas filling. In general I find the
green phosphor covered 'neons' much better for everything. This is the same
lamp and filling but 10 times brighter at the same current and insensitive to
electrode shape (or so it seems, since I can't see inside).

> > Please refer to a datasheet (f.ex. from CML) to see ignition voltages etc.
>
> If only.. I have NO idea who made these, or if they are even in
> business anymore.
> I just measured the ign voltage myself, and I'm using the low end of
> the 0.5 - 3mA current ranges I've seen on other "neon lamp" data
> sheets, like NE-51 and NE-52.

Please try this:

 http://www.cml-it.com/cgi-bin/htmlos.cgi/002125.3.226925588468068392

There are better versions of those datasheets on the web, with less cryptic
details, but I cannot find them. In general, dc ign. voltage > ac ign. voltage
(by 20-30%) and depends on temperature, age, previous life history (!) and
other things, such as present microwave radiation and ambient light. The
recommended minimum dc voltage for some lamps is 200V (before the resistor!) to
ensure ignition in fast applications (like multiplexed nixies).

With regards to current capability, I have to say that I blew one of these
things up. It was the sofite kind with a cartridge resistor, which I had
replaced with a piece of thick wire for direct operation. Later I forgot about
this and I put it in a panel I was building, for panel testing. When the
relevant relay was energized the thing exploded 30 cm in front of my eyes with
a blue-white flash peppering everyting with glass shards (I wear glasses), and
threw a 35Amp breaker in the process. I was quasi blind for 15 minutes. The
2.5mm^2 bit of wire that had replaced the resistor was welded in the case
(I cut it open to see after I could see again and after removing the glass
from my face with tweezers). Ever since I test each unmarked 'neon' indicator
for resistor presence before anything else.

hope this helps,
Peter P.


2007\09\29@150431 by Peter P.

picon face
David VanHorn <microbrix <at> gmail.com> writes:

> ??  These light at 55-60V, and are powered from batteries. 12x9V in this case.
> I think that's wrong. Light helps, the light knocks electrons loose
> from the metal.

Please see here (Max breakdown Voltage, DC, and Footnotes):

 http://www.cml-it.com/cgi-bin/htmlos.cgi/002288.2.424941928210712802

Apparently, adding another 4-5 batteries and series resistors might help. The
counter circuit had 22k resistors I think. The maximum current capability is
clear (at least once ...). Life seems to vary a lot, from 2000 to 25,000 hours
by type and by other parameters. As I was saying, I have had better luck with the
green ones.
 
Peter P.


2007\09\29@175144 by David VanHorn

picon face
>
>   http://www.cml-it.com/cgi-bin/htmlos.cgi/002125.3.226925588468068392

"No web site found at this address"..

2007\09\29@181434 by Peter P.

picon face
David VanHorn <microbrix <at> gmail.com> writes:
> >   http://www.cml-it.com/cgi-bin/htmlos.cgi/002125.3.226925588468068392

That seems to be the pdf server that wants to see a valid referrer address
before giving up what it has to serve.

Peter P.


2007\09\30@043954 by Peter P.

picon face

> "No web site found at this address"..

That site allows no 'inside' bookmarks. How clever, that must have been the
reason why I had to search for it so much. Verbal instructions:

 http://www.cml-it.com -> Neon -> WIH -> A1C

Please see Max Breakdown DC and Footnotes in the box.

Peter P.


2007\09\30@204132 by David VanHorn

picon face
On 9/30/07, Peter P. <TakeThisOuTplpeter2006EraseMEspamspam_OUTyahoo.com> wrote:
>
> > "No web site found at this address"..
>
> That site allows no 'inside' bookmarks. How clever, that must have been the
> reason why I had to search for it so much. Verbal instructions:

It's worse that that.. I'm on debian with epiphany web browser, the
nav bar dosen't display at all.. :-P

Anyway, I don't know whose neons these are, so I'm assuming 0.5mA,
which works out nicely to 33k, measuring the peak voltage across the
33k during the discharge.

So all those schematics I saw over the years, they were either wrong,
or assuming internal resistors in the lamps, yet I'm SURE I have seen
magazine articles with them where there was clearly no resistor.  Then
again, it wouldn't be the first magazine project I've seen that had
serious design issues.

2007\09\30@231455 by William \Chops\ Westfield

face picon face

On Sep 30, 2007, at 5:41 PM, David VanHorn wrote:

> So all those schematics I saw over the years, they were either wrong,
> or assuming internal resistors in the lamps, yet I'm SURE I have seen
> magazine articles with them where there was clearly no resistor.

The circuits you're talking about were the pre-LED, pre-
microcontroller "blink light" circuits, and current limiting  
resistors for the Neon bulbs were somewhat less common than they are  
in todays projects that drive LEDs from a microcontroller with no  
current limiting resistors.  I don't think that should be a BIG  
surprise.  There was no internet in those days to report problems  
with the Neon bulbs after a few hours of operation :-)

On the other hand, you may have problems with aged neon bulbs.  I  
wouldn't have thought that this would be a particular failure mode as  
bulbs got older, but I doubt that there's very much real data on how  
neon bulbs behave after a few decades (who knows HOW old neon bulbs  
you buy these days are.  I know how old the ones in my junkbox are!)

Were there ever any "professional" circuits that relied on the  
negative resistance behavior of neon bulbs?  I don't recall seeing  
anything other than use as indicator lights or "novelty flashers."

BillW


'[EE] Neon lamps'
2007\10\01@004433 by
picon face
back in the 50's when i was just getting into the hobby of electronics we
used
neons as voltage regulator for screen voltage and as tone generators for
code
practice oscillators,
some where in my collection of paper i have a circuit that i built with 16
neons
and it set on my work bench for years blinking away and it would randomly
change sequence.
it was powered from a line voltage supply.
de Jx


{Quote hidden}

> --

2007\10\01@004823 by

picon face
i also remember the first frequency counter that i came in contact with
was made by hewlett packard and it used decade counters with neons
for display seems like the model number was 524.
de Jx


{Quote hidden}

> --

2007\10\01@062043 by Peter P.

picon face
> > Were there ever any "professional" circuits that relied on the  
> > negative resistance behavior of neon bulbs?  I don't recall seeing  
> > anything other than use as indicator lights or "novelty flashers."

I am almost sure that no-one used neons as is in negative resistance mode
because that would have implied using them in arc mode (the negative resistance
appears in arc mode, i.e. at much higher current than in a glow discharge).
Anyway I meant to write "hysteresis behavior" and not negative resistance. It is
well known that the discharge characteristics can be controlled in many clever
ways with the electrode shape and gas pressure. Anything from abrupt hysteresis
through linear light-up [*] through negative resistance is possible. In general,
the life of discharge bulbs seems to be in reverse proportion to their size. A
large one with E27 socket from the 1930s is more likely to be operational than a
miniature neon from the 1960s or 1970s.

I know of at least two professional uses of neons in 1950s-1960s era equipment,
namely as pre-regulator in power supplies, for bias of the valved 'opamp' that
formed the regulator proper, and as set voltage detector in such apparatus as
xenon flash capacitor supplies. At least one of these used the neon in series
with a sensitive relay to remotely signal that the capacitor is charged and
ready to flash, in a studio flash unit.

[*] Look on Ebay for Russian made IN-9 and IN-13 linear bargraph 'neon' (and
Argon - purple) indicators. These make very nice VU meters for tube equipment.
A simple driver schematic is also available on the web, is uses a triode as
driver. The devices are current controlled with about 13mA needed for full
length light-up. They cost about $2 each (over 10cm long step-less bargraphs).
Links:

http://www.die-wuestens.de/rd/IN9-2.pdf

cgi.ebay.com/IN-9-NIXIE-BARGRAPH-TUBE-PURPLE-12-NEW-SUPER-PRICE_W0QQ
itemZ230175138681QQihZ013QQcategoryZ58174QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

(paste 2 lines)

This is unrelated to Dave's problem now, and I have no stake in those ebay sales.

Peter P.


2007\10\01@093123 by David VanHorn

picon face
Electronic organs used them in tone generators.



I have an update, I'd replaced 20 of the neons with new ones, using
33k resistors to limit max discharge current to 0.5mA (measured by
scope).  I'm planning to do the other 30 tonight.

Today, after a 48 hr burnin, I have one that's on continuous, and the
rest are nicely flashing. The glowing one I haven't investigated, but
it's surprisingly bright.

I'll look into upping the voltage, it does greatly affect the flash rate.

LEDs are SO much less trouble.. :)  An AVR, a couple of shift
registers, and a bunch of LEDs...  But in this case, that's not the
point, the lady I'm doing this for wanted a recreation of the box her
father built for her that got crushed in a move.   She's had any
number of guys tell her how easy they are to build, and then totally
fail to come through and actually BUILD one.


'[EE] Neon lamps'
2007\11\28@155039 by Barry Gershenfeld
face picon face
I just had to add my two cents to this six-weeks-ago thread that I just
came across.  I, too, built one of these "idiot boxes" whilst in junior
high school (late '60s).  I used NE-51's and it was powered from a
(technically) "dead" 200 volt photoflash battery.  It ran for a year or two
before I had to get another battery.  I probably ran it until I went to
college, and I can't be certain I didn't have it there as well.  I keep
hoping I will find it in the garage someday, since I never throw anything
away.  Each lamp used a single resistor in the classic fashion.  I never
had to replace a lamp.  Probable reason being that "200 volts always wins".

The number of lights was attributable to the number of junk TV sets I was
able to locate.  Each chassis in the high voltage section would yield up
one each 10 or 22 meg resistor, and a .1 at 400 volt mylar cap.   Then I
could add another light to the box.  I ended up with 13 lights.

Barry

2007\11\28@161012 by David VanHorn

picon face
This one will end up with 50, 10 and 22 meg resistors from VCCC, and
33k between the cap and neon.
Without the extra resistor, I was able to probe the current and watch
the lamp degrade over about an hour very significantly.
With the resistor, the current remains stable for many weeks.

Interesting. I didn't expect to learn anything on this project, but I did.  :)


'[EE] Neon lamps'
2007\12\02@115022 by Brooke Clarke
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face
Hi David:

Reference your message of Thu, 27 Sep 2007 15:57:15 -0400

While looking for something else I came across a U.S. patent for a survival
vest ID Light that uses a Neon lamp and a second neon lamp to extinguish the
main Neon lamp.  I've posted a redrawn schematic which includes the values at:
 http://www.prc68.com/I/LED.shtml#Neon
The main 3 Watt Neon lamp is described as not "self extinguishing".
You might be able to use one neon lamp running at 10 CPS to extinguish some
number of other lamps running around 1 CPS.  Or maybe a Johnson counter type
circuit when a lamp fires it also turns off a prior lamp?

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


'[EE] Neon lamps'
2008\01\08@221835 by Brooke Clarke
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face
Hi David VanHorn:

I know it's been a long time since you post but just came across another patent
that uses two different wattage Neon Lamps for the eyes of a toy bear.  It in
turn calls out more patents.  Use the FIND function of  your browser on my
Flashlights Patents web page: http://www.prc68.com/I/FlashlightPat.shtml
and search for 2647222 Toy Bear.

The patent has a schematic and circuit values.

--
Have Fun,

Brooke Clarke
http://www.prc68.com/Alpha.shtml  All my web pages listed based on html name
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam

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