I have an old Soviet personal radiation dosimeter that I broke as a kid by dropping it into water. I opened it up a while ago and the electronics in there were quite simple – mainly a ~10cm Geiger tube and what looked like Soviet variants of standard logic ICs. The tube looked intact – is there a way for me to test if it's worth salvaging, though?
Electronic – Testing an old Geiger tube
geiger-muller-tuberepairtest
Related Solutions
Speakers are AC devices, the cone will move with the waveform to make it audible. However, like Matt says, you should hear a click when you connect a DC supply, and another one if you remove the source. That doesn't contradict the AC behavior; when you connect the power supply the voltage steps up and for a very short time you get a alternating current. Striking a power wire against the connection may give you something more audible.
Best guess based on a Gargoyling skim consensus seems to be that
Lifetime is probably finite but largish.
Years to 10+ years of continuous operation in a non lethal environment seems very likely.Modern tubes (since about 1950~) tend to be halogen quenched.
- Particle impacts cause destruction of quench targets BUT halogen recombines subsequently leading to semi-infinite life
Many references refer to "extended" life rather than infinite. Some older one say infinite.
Older organic quenched tubes had a lifetime of about 10^8 events. So you could expect a "longer life tube to have say 10^10+ events life.
1 year = 8765 hours =~~ 3 x 10^7 seconds. So:
- 1 year life at 10^10 events ~= 300+ events / second average.
- = 10 years at 30+ events/second.
A Gargoyle search using
- geiger muller halogen quenched lifetime
produces results that look useful.
This is a 1957! paper that discusses the early days of Halogen quenched tubes. It thus tends to less gloss over things that may be taken for granted nowadays - and also he doesn't know things that nave been learned in the last 55 years :-). Useful and interesting though.
Firing cahatcteristics of halogen quenched Geiger muller tubes
Wow! 1972 Airforce Institute of Technology :-)
... investigation into ... short lifetime ...
No doubt pople havce long since come to grips with the problems described, but they give insight - lead solder reaction with Bromine and general Bromine attack causing depletion of the halogen quench gas.
Book Extract pages 103-104 especiall but generally fascinating
1960's halogen quenched tube:
Only passing relevance, but interest guaranteed :-)
Passing relevance. Page 53. BY James Van Allen :-) :-) :-) :-) !!!
From 1999 lab notes mentioned above - pages one & two
Best Answer
You have to apply a high voltage, like +500 V DC via 3 or more series resistors to the central anode, and connect the cathode via a 100 k\$\Omega\$ resistor to ground. The HV supply has only to source less than a mA. If an ionizing particle passes through the GM-tube, it will cause a brief discharge current, which in turn will give a brief pulse over the resistor.
You'll need a radioactive source to test it. The higher the radioactivity the more pulses per minute you'll get (and the more unhealthy it is!). The pulses are short, IIRC in the order of microseconds, depending on the kind of particle. You'll need a storage scope to see them, or trigger a monostable multivibrator (MMV) with them, so that they're stretched in time.