Geiger counter built in an Ohmmeter enclosure

Here’s a Geiger Counter that makes itself at home inside of an old Ohmmeter (translated). [Anilandro] set out to built this radiation detector in order to learn how they work. Like other diy Geiger Counter builds we’ve seen, this project assembles a circuit to interface with a gas-filled tube which serves as the detector. [Anilandro] takes a few paragraphs to discuss how this works; the Geiger tube is basically a capacitor whose electrical characteristics change as an ionizing particle passes through it.

Once he had the theory worked out he scavenged some parts to use. A broken emergency light donated its transformer to provide the high voltage needed. The rest of the circuit was built on some protoboard, and a speaker was added to output the clicking noises that have become a familiar part of the detector hardware. The tube itself is housed in a wand that attaches to the base unit through a cable. Check out some test footage of the finished unit after the break.

[Thanks J]

Comments

  1. Nice hack!

    BTW you can make a basic alpha detector ionisation chamber using a single JFET and a suitable chamber with a sensor glued to it in order to offset temperature drift.

    I also ran into an interesting variant which uses two chambers side by side in a single cylinder with a magnet on the end to divert particles into one or the other depending on polarity.
    You can actually detect the type of beta (electron or positron) this way!

  2. billwcf says:

    Nice Design.
    Anybody that quickly wants to experiment with Geigers can buy a cheap Russian tube off ebay and use a ccfl driver (from Digikey) and a rectifier and possibly a voltage doubler (depending on the tube). Here is an open source discussion on a Geiger counter being built to be a standard to measure gammas from silver neutron activation. Be warned, the little ccfl drivers pack a wallop. -bill

    http://www.coultersmithing.com/forums/viewtopic.php?f=11&t=259&start=20#p1496

  3. Koldfuzion says:

    I’m curious, what is he using to calibrate and test the system?

  4. Parcanman says:

    That little disc is the testing source, I’ve seen ones that color before made of Cobalt, but in this one the resolution of the video is too low to make out what it says.

    You could pull a small 2 microcurie Americium-241 source sample out of an ionization smoke detector if you wanted to try this out.

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