Fun-Size Geiger Counter Sits atop a 9-Volt Battery

Want a little heads-up before walking into a potentially dangerous radioactive area? Sure, we all do. But the typical surplus Civil Defense Geiger counter is just too bulky to fit into the sleek, modern every-day carry of the smartphone age. So why not slim down your first line of defense against achieving mutant status with this tiny Geiger counter (Facebook)?

We jest about the use cases for a personal-sized Geiger counter, as [Ian King]’s inspiration for this miniaturized build was based more on a fascination with quantifying the unseen world around us. Details are thin in his post, but [Ian] kindly shared the backstory for this build with us. Working on a budget and mostly with spare parts, the big outlay in the BOM was $20 for a Soviet-era SBM-10 tube, itself a marvel of miniaturization. While waiting the two months needed for the tube to arrive, [Ian] whipped up a perf board circuit with a simple oscillator and a CFL transformer to provide the 400 volts needed for the tube. The whole circuit, complete with tiny speaker and an LED to indicate pulses, sits neatly on top of a 9-volt battery. The video below shows it in action with a test source.

Geiger counters are not exactly rare projects on Hackaday, and with good reason. Take a look at this no-solder scrap bin counter or this traveling GPS Geiger counter built dead-bug style.

Thanks to [Cyphixia] for spotting this one for us.

29 thoughts on “Fun-Size Geiger Counter Sits atop a 9-Volt Battery

        1. a LED VU meter module that already has the circuitry for analog volume sampling and a fairly high-impedance could be used with a capacitor to capture a tick rate into an analog level without much circuitry (or a 555). Calibrating it is still RC based like a 555, but you don’t really need a digital counter or a square wave to deal with it.

        1. And up. Judging from the rebuild kits made available, there is a modest subculture of rebuilders out there too. Russian Geiger-Muller tubes of various flavors are still in the $10 – $20 range though and there seems to be a bunch of Chinese “radiation detectors” and phone-plugin dongles but it’s unclear what method they’re using.

    1. Radon is the biggest that there. Followed by dust and not washing your hands and boots.
      Even reactor grade rods are safe to handle as long as they’ve never been used. A brick and mortar storage bin should block the majority of the radiation from your collection.
      But as you said a geiger counter (paired with a film badge) would be improvements.

        1. Someone on another site recently linked to the FCC.gov site for requesting information, and I was appalled to see google analytics running on it, I mean on .gov sites now? WTF.
          And it’s even worse when I see it on government sites of other countries, which I unfortunately sometimes do.

          Meanwhile there is suppose to be a special ‘cyber command and ‘cyber unit’ and all that crap in the US, funded with billions, and then they use goddamn Google and such 3rd parties to run scripts on their sites, including sites handling personal information.

          Personally I refuse to use government sites with 3rd linked party scripts.

  1. Has a few assorted tubes here.
    The biggest problem is that small displays are hard to find. Ideally you want a needle purely for the retro factor but a small LCD panel eg from a mini calculator with attached PCB shard should work fine.
    I found that if you are careful driving them from an Arduino is feasible or you could use semi-discrete drivers like a PIC 10F222 with CLK/4 output on as this can drive up to four pins at a time.
    You only need two of them if the inputs are configured properly and LCD can be Charlieplexed to reduce pin count to sensible levels for a “bargraph” or fake needle display.
    LED backlight can be made easily enough with Boots blue light cure nail varnish or use EL wire/sheet froman old watch.

    1. KingBright makes a 0.2-inch 7-segment display. do you need more than 1 digit for your counter? Make it a scale of 0 to 9 for how bad things are. have a flashing “H” if it is too high or something.

  2. Also found that “Step” counters are suitable if you repurpose the display. Some are even a standard OTP uC and can be reprogrammed somewhat by zeroing the first couple hundred bytes and using suitably compacted code to fit in the remaining space.

  3. Nice and small result. Now what? This sort of thing would work well just sitting on the shelf providing the odd, soothing click from background radiation. But for that purpose, the 400V source would have to be super efficient…. eliminate the red “on” LED, and change batteries to a less expensive and higher capacity. Something like 6 months operation at minimum.

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