DIY Geiger Counter

Ever since a neighbor (a physics professor) let Dan Julio borrow and use a Geiger counter as a child, he has been fascinated by these devices… and kind of wanted one. He finally decided to build his own, and documented the project here.

The heart of this device is an LND-712 alpha-beta-gamma radiation detector, which interfaces with an ESP32-based LILYGO T-Display for processing and visual output. It shows counts per minute in a convenient dial format, along with an estimated radiation dosing in sieverts/hour. It also calculates the device’s cumulative radiation dose, which can be reset as needed.

While the device could provide a general idea of radiation values, Julio is quick to note that it is uncalibrated, and as such it should not be used for critical measurements. He also mentions that while he doesn't expect others to construct this actual device, having the documentation out there allows others to pick and choose from this information.

The device is constructed as a series of linked devices, including the detector itself and a high-voltage Geiger probe driver, RGB lighting unit, battery, audible clicker, and the T-Display. Notably, the clicker is based around a 555 timer, which was constructed before the T-Display was implemented to get basic feedback from the detector/driver unit. It could certainly be replaced with a GPIO pin – and possibly a transistor – but it is still a neat feature as-is.

The whole thing is finished off with a nifty 3D-printed enclosure, enabling Julio to take it with him on all his (non-critical) radiation measurement adventures. If you’ve been considering building a radiation detection device (or are now), be sure to check out the write-up!