Summary of Building a PIN Diode Geiger Counter
This article details the construction of a PIN Photodiode-based Geiger Counter, inspired by curiosity about uranium's green glow and recent nuclear disasters. The author modified existing designs to detect beta and gamma radiation using two BPW34 photodiodes connected in parallel. Unlike standard methods using tin foil for light protection, this design dips the diodes in liquid rubber (Plasti Dip) to allow beta particles to reach the semiconductor while still shielding against light. A 9V battery is used to amplify pulse height, and transistors are employed to boost voltage fluctuations caused by radiation strikes.
Parts used in the PIN Photodiode based Geiger Counter:
- Two BPW34 photodiodes
- Two transistors
- 9 Volt battery
- Liquid rubber (Plasti Dip)
Exactly 30 years ago a great disaster struck the region of Chernobyl: a nuclear accident occurred that released a large quantity of radioactive particles into the atmosphere. And it is only five years ago that, with the Fukushima Daiichi nuclear disaster, a second similar catastrophic event has taken place.
These anniversaries did not directly let me build a PIN Photodiode based Geiger Counter, it is more or less a coincidence. The main drive to build such a device was my curiosity and (please forgive me) a fascinating green glow I’ve seen on various fluorescent Uranium minerals under UV light. But in this context it should not be forgotten that at present there still is a significant increase in background radiation in some regions and some agricultural products due to these events.
There are lots of descriptions of how to build such a device; even cheap commercial products (e.g. the Smart Geiger) use such a design. Especially two sites caught my attention: OpenGeiger.de and Das Gammastrahlen-Mikrofon (German). The design I’ve chosen is based on these sources but I’ve begun to further modify it. In this post I’m showing the design I’ve started with. It mainly relies on two BPW34 (Vishay Datasheet) photodiodes connected in parallel, and two transistors to amplify the voltage fluctuations of beta and/or gamma rays striking the diodes. A 9 Volt battery was added to increase the pulse height.
The common approach to protect the photodiodes from light is to use one layer of tin foil and connect it to ground. This should also protect the circuit against electromagnetic radiation. I’ve started with something different and dipped the diodes three times into liquid rubber (Plasti Dip). My hope was to at least allow some beta particles to reach the semiconductor material.
Read more: Building a PIN Diode Geiger Counter
- What drives the build of this device?
The main drive was curiosity and the fascination with the green glow seen on fluorescent Uranium minerals under UV light. - Can I use tin foil to protect the photodiodes from light?
The common approach uses one layer of tin foil connected to ground, but the author chose a different method. - How does the author protect the diodes from light?
The author dipped the diodes three times into liquid rubber known as Plasti Dip. - Does the Plasti Dip coating block all radiation?
No, the hope was that the coating would at least allow some beta particles to reach the semiconductor material. - What components are used to amplify voltage fluctuations?
Two transistors are used to amplify the voltage fluctuations of beta and/or gamma rays striking the diodes. - Why was a 9 Volt battery added?
A 9 Volt battery was added to increase the pulse height of the detected signals. - Which commercial product uses a similar design?
Smart Geiger is mentioned as a cheap commercial product that uses such a design. - Are there other sites recommended for building this device?
Yes, OpenGeiger.de and Das Gammastrahlen-Mikrofon are two sites that caught the author's attention.
