SparkFun Geiger Counter
A USB-powered Geiger counter built around an ATMega328 microcontroller and LND712 Geiger tube. Outputs random bits generated from background radiation events in real time via serial at 9600 bps — each ASCII 0 or 1 represents an actual event in the tube, which can be used to calculate CPM or generate true random numbers.
The board features an improved voltage regulation circuit for clean tube output and an active-high signal capture circuit that pushes the CPM limit to 100 Hz. Ships with the Arduino bootloader pre-loaded (use board type "Arduino Pro or Pro Mini, ATmega328, 3.3V, 8 MHz").
Key Features
- LND712 Geiger Tube – Operates at 560 V, detects alpha, beta, and gamma radiation
- ATMega328 Microcontroller – Arduino-compatible, programmable in-circuit
- FTDI USB Interface – Serial output at 9600 bps (requires FTDI drivers)
- TTL Active-High Output Pin – Direct tube event signal for external use
- 5 V Logic – 30 mA total current draw
- Power & Status LEDs
- Dimensions – 4.15 × 1.75 × 1" (without standoffs)
Warning — High Voltage: When powered with the switch in the ON position, the board contains exposed high-voltage components. To turn off safely, flip the tube power switch to OFF while the USB cable is still connected — this bleeds the high-voltage lines through a resistor to ground. Do not touch the end window of the Geiger tube or any conductive region inside the area marked "HIGH VOLTAGE" when powered. An enclosure is strongly recommended.
Note: The Geiger tube ships with a red protective boot over the end window. Remove it to detect alpha particles — gamma and beta particles are detectable with the boot on. This product is for educational purposes and should not be relied upon for health or safety determinations.
Resources
- Schematic
- Eagle Files
- GitHub Repository
- Firmware (ships with v12)
The SparkFun Geiger Counter appears in the following collections:
SKU SF-SEN-11345
by Little Bird
