Ryan Jordan‘s Derelict Electronics workshop helps participants create amplifiers out of rocks:
In this workshop we will use a mesh of point contacts connecting to chalcopyrite and iron pyrite to make crude amplifiers out of rocks. When an electric current is sent through the rocks sporadic noise bursts from the speakers. With some fine tuning these rocks begin to behave like microphones, amplifying howling feedback and detecting subtle scratches and disturbances in their surrounding environment. Occasionally the circuit exhibits visual output coinciding with the audible in the form of small sparks and minute explosions occurring where the copper point contacts meet the surface of the rock.
This crude amplifier is based on the Adams Crystal Amplifier 1933, a precursor to the modern transistor.
The second session involves creating a DIY solar cell out of copper and copper oxide.