Some of the geiger counter kits from Electronics Goldmine use a chain of NE-2 bulbs as their HV DC regulator. "NE-2 bulbs with resistors" Cut off the resistors, just use a chain of neon lamps alone.
Using NE2 bulbs as voltage regulators
Started by ●August 9, 2015
Reply by ●August 9, 20152015-08-09
Reply by ●August 9, 20152015-08-09
>"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.
Reply by ●August 9, 20152015-08-09
>"I would try to come up with a circuit that used one neon bulb across part of a >voltage divider to do the regulating. I think trying to use 5 or 6 in series >would lead to very erratic behaviour.> Dan "Agreed, in fact I just posted something to that effect almost.
Reply by ●August 9, 20152015-08-09
On Sun, 9 Aug 2015 15:25:27 -0700 (PDT), 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 ?No. The radiation only lowers the threshold voltage by ionizing some of the gas inside the bulb. It has the same effect as shining a light on the NE-2 to produce the "dark effect". Once the lamp "fires", the lamp is full of ionized gas, which keeps the neon lamp turned on (hysteresis). Once "fired", the operating voltage remains constant and is unaffected by the radiation. Therefore, no change in regulation voltage.>And I say just use one and use resistors like they did >in the earlier solid state analog "pass transistor" type regulator >controllers.Supposedly, you can use the neon lamp threshold effect to build a gamma ray radiation detector without the GM tube or PIN diode detector (alpha and beta won't go through the thick NE-2 glass envelope): <http://electronicdesign.com/test-amp-measurement/simple-geiger-detector-uses-neon-glow-lamp> <http://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/files/29/1634/figure_01.gif> Of course, there are those in this newsgroups who claim it doesn't work: <https://groups.google.com/forum/#!topic/sci.electronics.design/8SBFx8tEBe0> If you don't like high voltage, there are also PIN diode and solar cell radiation detectors: <http://www.maximintegrated.com/en/app-notes/index.mvp/id/2236> <http://www.carroll-ramsey.com/detect.htm> <http://hackaday.com/2013/06/03/a-very-tiny-gamma-ray-detector/> <https://www.sparkfun.com/products/9541> Or, you can buy one ready to play for your Android or iThing: <http://www.ebay.com/sch/i.html?_nkw=android+radiation+detector> A friend bought one and we compared it to my CD-700 GM counter. It worked and would detect my sources, but at far lower cpm (counts per min). Actually, the sensitivity is about the same, but the capture area of the PIN diode is much smaller than the GM tube. -- 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 ●August 9, 20152015-08-09
On Sun, 9 Aug 2015 04:49:03 +0000 (UTC), "Geoffrey S. Mendelson" <gsm@mendelson.com> wrote: (...) Never mind using neon bulbs as regulators. Use zener diodes. 400V High Voltage Regulator. $7.50 <http://uraniumrocks.com/collections/cdv-700-parts-and-upgrades/products/400v-high-voltage-regulator-for-cdv-700-use-with-russian-gm-tubes> -- 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 ●August 9, 20152015-08-09
In article <lunfsa1bgrq05vl2fv3a1hf7g53qjbc7m2@4ax.com>, jeffl@cruzio.com says...> > On Sun, 9 Aug 2015 04:49:03 +0000 (UTC), "Geoffrey S. Mendelson" > <gsm@mendelson.com> wrote: > (...) > > Never mind using neon bulbs as regulators. Use zener diodes. > > 400V High Voltage Regulator. $7.50 > <http://uraniumrocks.com/collections/cdv-700-parts-and-upgrades/products/400v-high-voltage-regulator-for-cdv-700-use-with-russian-gm-tubes>I bet that website is on the watch list :) Jamie
Reply by ●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 ●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 ●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 ●August 9, 20152015-08-09
On Sun, 9 Aug 2015 19:48:13 -0400, M Philbrook <jamie_ka1lpa@charter.net> wrote:>In article <lunfsa1bgrq05vl2fv3a1hf7g53qjbc7m2@4ax.com>, >jeffl@cruzio.com says...>400V High Voltage Regulator. $7.50 ><http://uraniumrocks.com/collections/cdv-700-parts-and-upgrades/products/400v-high-voltage-regulator-for-cdv-700-use-with-russian-gm-tubes>>I bet that website is on the watch list :) >JamieI 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
