NuclearWarDetector
| Project Nuclear War Detector | |
|---|---|
| |
| Alerts for thermonuclear war and/or other large radioactive incidents. | |
| Status | Initializing |
| Contact | thomas |
| Last Update | 2018-12-17 |
Introduction
Inspired by a design from Charles Wenzel of TechLib.com, I made a radiation detector designed to react only to extreme levels of high energy gamma radiation. It is a simple pin-diode type detector, and while it does respond to normal levels of background radiation, it only emits a click once every 15 minutes or so. When exposed to sufficiently ridiculous levels of radiation it will emit a somewhat weak and irritating whine, alerting participants at the space to a possibly ongoing nuclear apocalypse. To quote Mr. Wenzel: "Being caught off guard by a nuclear war can be inconvenient. This project should alert the utterly unobservant individual to any significant nuclear exchange or radiation spill in the immediate vicinity, giving the owner time to kiss various body parts goodbye."
Circuit
The November 2011 issue of Elektor magazine included a somewhat improved iteration of an early design for a simple PIN diode radiation detector. I took their circuit, shrunk it down with smd parts, and combined it with a comparator and active buzzer to make a bare-bones radiation detector. It works by reverse-biasing the photodiode in complete darkness. A sufficiently energetic gamma ray will present as a tiny pulse across the diode, which is then amplified by a jfet and a simple opamp. This signal is fed into the comparator, triggering an LED and causing the active buzzer to emit a short audible click. Thanks to the active buzzer a higher count rate will first devolve into a mildly irritating squeal, subsequently building to a whiny (and frankly complainatory) note when the device is exposed to skin-sloughing levels of radiation.
Normal function
It will emit a barely audible click once every 15 minutes or so during normal operation. This is not cause for alarm. Stronger sources such as a radium watch hands will cause it to click at a rate of up to 60CPM, but only if the source is held directly over the sensor package.
Problems
Due to microphonics, any impacts or heavy vibrations will cause the sensor to trigger, but this will only register as short intermittent clicks. The bare-bones comparator design (with a simple voltage divider as reference) does have a downside though, as the detector is quite sensitive to voltage fluctuations. I've set the threshold so that the unit will continue to function up to 5.2V, but above that level the sensor will behave in a manner indistinguishable from its highest alarm condition. This admittedly regrettable flaw in my design may be remedied with a voltage reference at some future date :p
Current Status
The sensor is complete and functional, all that remains is to build a case for it.
Gallery
Sensor package itself.
Sealed with copper tape.
Completed pcb. Further light-proofing with electrical tape.
Triggered.
