FAQ - Geiger counter - A basic hookup circuit
Posted: Tue May 12, 2009 2:20 pm
I have published this before, but I don't think in an FAQ. Here it is. A simple five component hook up
1. Variable power supply 0 to 1500 volt variable
2. Simple radio shack audio amp and speaker combo (1Vp-p input)
3. Any geiger detector tube
4. One capacitor .001 - .005 @ 2-3kv
5. One resistor 3.3 or 3.9 megohms (three 1 meg resistors in series is best.)
Oh, you must also have a decent source of radiation handy, U ore, radium dial, etc.
The supply need not be able to supply more than 1ma at most.
The audio amp can be any small amp or even a hi-fi amp be sure to use the high level input that needs to be about 1v P-P and not a low signal preamp input or you will overdrive the amp.
The GM tube can be of any type as the supply will work any GM tube over about a 500-1200 volt range normally found in these tubes.
The resistor needs to be physically large, (long) to stand off and evenly distribute voltage. This why a small series string is recommended.
The image below is obvious as it is diagramatic in nature and not schematic. This was produced specifically for one type of tube, but is completely generic in nature for all tubes.
Be sure to turn up the volume on the amp so that the onset of GM action can be heard.
Once the clicking due to a nearby source of radiation is heard, you should be able to safely advance the supply another 50 volts to put you well onto the geiger plateau region. Never raise the voltage more than 100 volts over the onset of clicking.
If you span the full voltage of the supply and get no clicking, then the GM tube is bad.
For a vastly more involved FAQ checdk out...
viewtopic.php?f=13&t=5347&hilit=FAQ#p33791
Richard Hull
1. Variable power supply 0 to 1500 volt variable
2. Simple radio shack audio amp and speaker combo (1Vp-p input)
3. Any geiger detector tube
4. One capacitor .001 - .005 @ 2-3kv
5. One resistor 3.3 or 3.9 megohms (three 1 meg resistors in series is best.)
Oh, you must also have a decent source of radiation handy, U ore, radium dial, etc.
The supply need not be able to supply more than 1ma at most.
The audio amp can be any small amp or even a hi-fi amp be sure to use the high level input that needs to be about 1v P-P and not a low signal preamp input or you will overdrive the amp.
The GM tube can be of any type as the supply will work any GM tube over about a 500-1200 volt range normally found in these tubes.
The resistor needs to be physically large, (long) to stand off and evenly distribute voltage. This why a small series string is recommended.
The image below is obvious as it is diagramatic in nature and not schematic. This was produced specifically for one type of tube, but is completely generic in nature for all tubes.
Be sure to turn up the volume on the amp so that the onset of GM action can be heard.
Once the clicking due to a nearby source of radiation is heard, you should be able to safely advance the supply another 50 volts to put you well onto the geiger plateau region. Never raise the voltage more than 100 volts over the onset of clicking.
If you span the full voltage of the supply and get no clicking, then the GM tube is bad.
For a vastly more involved FAQ checdk out...
viewtopic.php?f=13&t=5347&hilit=FAQ#p33791
Richard Hull