DIY Geiger Counter Is Sure To Generate Clicks

On the outside, a Geiger counter seems like a complicated thing. And you might think a device that detects a dangerous, mostly invisible threat like radiation should be complicated. But they’re actually pretty simple. The Geiger-Muller tube does most of the work, which boils down to detecting brief moments of conductivity caused by chain reactions of charged particles in radioactive materials.

[Prabhat_] wanted to build a unique-looking Geiger counter, and we’d say that this slick, Star Trek-esque result succeeds. A well-organized display shows the effective dose rate, counts per minute, and cumulative dose, which can be displayed in either microsieverts or millirems. We dig the 3D printed case design, because we like to see form follow function.

The counter is powered by an 18650 cell that’s DC-to-DC boosted to 400+ volts. A NodeMCU processes the signal coming in from the G-M tube and expresses it in both clicks and LED blinks, both of which can be toggled on or off from the home screen. The alert threshold can be customized in the settings, which means the point at which green changes to red.

Click-click-click past the break for [prabhat_]’s great walk-through video, where he tests it with uranium ore and a thoriated gas lantern mantle.

If you want to take the opposite approach and get to clicking ASAP, well, fire up your hot glue gun and dump out your scrap bin.

19 thoughts on “DIY Geiger Counter Is Sure To Generate Clicks

  1. A GM tube detector cannot differentiate accumulated dose, as it cannot quantify the amount of energy in a given quanta- it only can count events. If you know the source material, it can be entered to approximate a given dose by the counts, but this really doesn’t make the device useful in the field, given the variety of nucleides that can be present in nature, or in an industrial accident.

    I am sure this was a fun project, but keep in mind that it is really just an event counter/ rate indicator, not an absorbed dose /dosimeter.

    1. Maker of the project here! You’re right that Geiger counters can’t give you an accurate dose reading. You’d need a proper scintillation counter/spectrometer for that. But I did calibrate this tube using a source of Cs-137 (gamma energy 662 KeV) so it would be reasonably accurate for that isotope (as long as you blocked the betas, since those are over-represented too).
      Most commercially available Geiger counters seem to be calibrated to Cs-137 since it’s gamma energy is close to the average energy found at nuclear accident sites and in the fallout from nukes.

  2. Hi. Intriguing, I have a few projects that need lots of smaller tubes.
    Incidentally can you please PM me on Twitter (darnstadium) if possible, kthx.
    Might be better than the PSU I am using.

  3. Fun looking build. I wonder what eats all that power (180 mA @ 3.7V, giving an 11 hour battery life, they said). My similar-ish (but smaller display) GMC-320 consumes about a tenth that much power, giving several days autonomy and recording before needing to find a USB plug (and dumping the logged data).

    1. It’s down to 140mA now that I’ve disabled the wifi through code (since I’m not using it), but most of the power is going into the display (~80 mA). There’s also a 4.2V boost converter supplying a stable voltage to the HV converter, and a linear regulator on the nodeMCU so the inefficiencies add up.

  4. “…caused by chain reactions of charged particles in radioactive materials.” Something lost in translation or an editing oops? The avalanche “chain reaction” in the G-M tube definitely doesn’t happen in radioactive material. And radioactive material doesn’t really involve “chain reactions of charged particles” unless you’re counting fluorescence or scattering events that are really incidental to the radioactivity.

  5. i’m just looking at the pcbs i ordered because i was too lazy to make my own.
    let’s just say a HV trace with a couple hundred volts does not belong within 0.1mm of other traces… -.-

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