>" Perhaps you are confusing the striking voltage with the on/regulating
>voltage (different ionization levels,look in Handbook of Chemistry and
>Physics). "
Something I never had cause to look into, but if that voltage really is that stable I guess that is sort of the tube equivalent of a Zener diode, bidirectional in fact.
Their solid-state HV regulator is a lot noisier than the Codatron(R),
roughly as bad as the regulators that Titan Industries used to make.
Reply by Robert Baer●August 11, 20152015-08-11
jurb6006@gmail.com wrote:
>> "Why bother shielding the NE-2s? A bit of radiation or UVA will improve the turn->on performance, and is pretty unlikely to be noticed in operation. "
>
> Wouldn't that change the ionization somehow and thus the intrinsic voltage drop needed to regulate voltage ?
>
> And I say just use one and use resistors like they did in the earlier solid state analog "pass transistor" type regulator controllers.
>
>
Perhaps you are confusing the striking voltage with the on/regulating
voltage (different ionization levels,look in Handbook of Chemistry and
Physics).
Reply by Robert Baer●August 11, 20152015-08-11
bitrex wrote:
> On 8/9/2015 7:36 AM, Phil Hobbs wrote:
>> Why bother shielding the NE-2s? A bit of radiation or UVA will improve
>> the turn-on performance, and is pretty unlikely to be noticed in
>> operation.
>>
>> Cheers
>>
>> Phil Hobbs
>>
>
> Indeed, I think some glow tubes were manufactured back in the day with a
> small amount of radioactive material to encourage ionization in dark
> environments.
That was one of the tricks that Victoreen did for their Corotron(TM)
high voltage regulators.
Reply by Jeff Liebermann●August 9, 20152015-08-09
On Sun, 9 Aug 2015 19:48:13 -0400, M Philbrook
<jamie_ka1lpa@charter.net> wrote:
>I bet that website is on the watch list :)
>Jamie
I don't have a watch list. I keep a collection of bookmarks on
CDV-700 repairs because I was receiving about one related repair
question per month. The short story is that I own exactly one CDV-700
6B Lionel GM Survey Meter:
<http://www.orau.org/ptp/collection/civildefense/cdv700.htm>
Thanks to my inept initial repairs, I had some difficulties getting it
to work reliably. I compounded my mistake by allowing the two D cell
batteries to leak all over the inside. After a few assorted questions
and answers in various Yahoo groups, I managed to fix it. Since then,
I've repaired 5 similar meters, mostly by careful cleaning the
phenolic PCB. Two had sick GV3A Corotron regulator tubes, which I
replaced with a string of zener diodes totaling 900v. I also replace
the nearby high voltage disc capacitors which ocassionally arc over
and short.
Would you believe only 2 transistors?
<http://www.dvq.com/geiger/cdv700_6.jpg>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Reply by Jeff Liebermann●August 9, 20152015-08-09
On Mon, 10 Aug 2015 00:16:34 +0000 (UTC), Frank Miles
<fpm@u.washington.edu> wrote:
>Back in the day, Tektronix used neons as power indicators. They
>subsequently banned them from this service as all too often their
>negative dynamic resistance oscillated with the stray wiring
>capacitance (as in Jeff L's example). This could get into other
>parts of the 'scopes and cause real mischief.
Yep. I have two Tektronix T922 scopes. They're the one's on the top
of the pile:
<http://802.11junk.com/jeffl/crud/scopes-to-be-fixed.jpg>
<http://www.logwell.com/tech/oscilloscopes/T922R_service_notes.html>
"T922Rs below serial number B011950 have a neon power
indicator pilot lamp, and those with serial number B011950
and up have an LED power indicator."
Both of mine came with the a neon indicator, which could sometimes be
visually seen oscillating at about 2 Hz. There is a 1uf across the
neon lamp and 100K resistor in series. It's powered by +100v
unregulated, which should be high enough to prevent oscillation, but
doesn't. Per a suggestion on the Yahoo TekScopes group, I replaced it
with an LED. The 2 Hz glitches on the slow sweeps went away.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Reply by whit3rd●August 9, 20152015-08-09
On Saturday, August 8, 2015 at 9:49:07 PM UTC-7, Geoffrey S. Mendelson wrote:
> I am building an experimental radiation detector. Being an experiment, I
> want to avoid buying anything for it. Sort of a junkbox project...
> The geiger muler tubes I have require 400 volts. I could do it easily buy
> buying 200 volt zener diodes and put two in series.
The principle of a Geiger detector is that it stores VERY LITTLE energy, and
the HV supply isn't regulated, it takes a drastic drop every time a particle
is detected, Use a transformer-winding ratio and battery supply
at (nearly constant) voltage will give you a steady-enough HV source.
Reply by Frank Miles●August 9, 20152015-08-09
On Sat, 08 Aug 2015 23:16:18 -0700, Jeff Liebermann wrote:
> On Sun, 9 Aug 2015 04:49:03 +0000 (UTC), "Geoffrey S. Mendelson"
> <gsm@mendelson.com> wrote:
>
>>What I do have is 50 NE2 bulbs with resitors. Could I use those?
>>
>>It would probably take 5 or 6 in series to do it, which compared to two
>>5 cent zeners from eBay seems like a waste of money and circuit board
>>real estate, but I am looking to do something that does not require me
>>to order anything from anyone.
>
> The last time I tried to use a neon lamp as a voltage regulator, I
> managed to build to perfectly functional relaxation oscillator instead.
> Try googling for a GM power supply schematic:
> <https://www.google.com/search?tbm=isch&q=geiger+counter+power+supply
+schematic>
> See any that use neon lamp regulators? That should be a clue.
>
> My antique CDV-900 counter uses a 900v regulator tube made by Victoreen.
> <http://www.logwell.com/tech/dhdwe/HV_woes.html>
> <http://www.logwell.com/products/Codatron_Corotron.html>
> There's a difference between these and neon lamps, but I don't recall
> the details. The designer of these replacements is someone that posts
> regularly to this newsgroup.
Back in the day, Tektronix used neons as power indicators. They
subsequently banned them from this service as all too often their
negative dynamic resistance oscillated with the stray wiring
capacitance (as in Jeff L's example). This could get into other
parts of the 'scopes and cause real mischief.
Reply by M Philbrook●August 9, 20152015-08-09
In article <lunfsa1bgrq05vl2fv3a1hf7g53qjbc7m2@4ax.com>,
jeffl@cruzio.com says...