This is a simple induction coil that detects the presence of an RFID reader. The participant can use it to scan their environment to discover where their data is being collected. This was developed as a series of simple physics experiments, and kits were given out at a workshop at the Conflux Festival at NYU in 2010.
Testing the waveform with an oscilloscope.
Forming the coil.
Made with: magnet wire, an LED, solder, glue, a chopstick.
Thanks to: NYC Resistor, for all their advice.