I love my Flipper Zero, I want to maximize its utility in every possible way. I use the great akopachov's Authenticator every day and Mayhem v2 adds everything else I need... however, living in Norway, in close proximity to Russia, there's one essential addition that I believe should be considered: a Geiger Counter.

I saw some great approaches to this, but I need something that just works, no fiddling around. The beauty of this Geiger Counter is that it seamlessly integrates with the Flipper, drawing power from it, uses its display, and stores the data to it. It's the perfect symbiosis, an essential addition to my toolkit.

The design is heavily based on schematics using a J305 Geiger–Müller tube for the flipper form factor.

This app gives you a graph view with counts per second (instantaneous measure of the radioactivity) as CPS and per minute as CPM.

There is extra functionality to record, zoom, change units, etc.

(credits to nmrr)

With this app you can get a really random dice based on the geiger counter. Make your decisions and board games extra exciting.

(credits to nmrr)

You can buy a kit or an assembled unit from Tindie.

You can go full DIY with this Geiger Counter Kit https://s.click.aliexpress.com/e/_DkShdV9 and follow the instructions from https://github.com/nmrr/flipperzero-geigercounter

You only need some wires, pins and a 3.5mm headphone jack.

If you got the prepopulated extra PCB, you need to solder few components:

Only calibrate if you assembled the PCB. If it was pre-assembled, it is already calibrated. You need 50M ohm resistors and a multimeter. Check more details about the process here.

1. Keep the device disconnected from power. Remove the geiger tube if is installed

2. Adjust R100 to 50 ohms

3. Set the multimeter to VDC, highest range (i.e. 400V).

4. Connect GND to the multimeter (i.e. the left tube clamp)

5. Connect the positive tube clamp to the multimeter positive probe, using 50M ohm in resistors between them

6. Power the device and adjust R100 until your multimeter shows 57V (if is a 10M multimeter) or 6.5V (if is a 1M multimeter).

The device is now calibrated. Now you can place the geiger tube. You might add a dab of glue to hold the potentiomenter R100 in place.