Geiger Detector with Neon Bulb

Well, this is not about using the Neon bulb as detector element itself, but using the Neon bulb as readout element. The Neon bulb as detector was tried by experts and they found it doesn't work. At least not with radiation intensities emitted by off-the-shelf radiation sources.

The Geiger-Müller tube is hooked up to the high voltage supply with a resistor. You need to experiment here, since it depends on the tube and the neon bulb, but start with a value of 10 megaohms. The GM tube is then connected to the neon bulb, which goes to ground.

Now we are ready to test: turn on the high voltage. Now you need to dampen light, since the flashes in the neon bulb are VERY faint and impossible to observe in daylight or even with the lights on in the laboratory. You even may have to switch off the lights completely.

If you don't see any flashes at all, and you made sure that all connections in the circuit are good, the high voltage is working, decrease the value of the resistor and test again. But bear in mind that, the bigger the current thru the Geiger tube when it has ignited, the shorter the lifetime.

I had good results with a CK1049 Geiger tube, a 2.7 megaohms resistor and a neon bulb from a screwdriver-voltage-tester. High voltage was at 900V.

Be very careful when handling high voltages!
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