Ashish Derhgawen built a coherer-based receiver with a simple decoherer mechanism, and connected it to a Beaglebone to decode the received signals:
In my last post, I described how I made a spark-gap transmitter and receiver. For the transmitter, I used a car’s ignition coil to produce high voltage sparks, and for the receiver, I used a coherer to detect the transmissions. A coherer is a simple device – it consists of iron filings between two electrodes. Normally the filings have very high electrical resistance (tens of megaohms), but when the coherer detects electromagnetic waves, its resistance drops to about 10-20 ohms.
More details at Ashish’s blog.
Check out the video after the break.