Experimenting with a Luminescent "Capacitor" By Forrest M. Mims III How to Couple a Luminescent "Capacitor" to a Photoresistor or Photodiode Luminescent materials are analogous to capacitors in that they can be "charged" with light. Thereafter, they slowly release light, albeit with a wavelength range that may not match that of the charging light.
Voltage Probe with Tone and LED Outputs Troubleshooting your circuit: How to build an inexpensive voltage probe.
Infrared Remote Control Tester Quickly figure out if the batteries in your TV remote control need to be replaced.
Making Music with an Atari Punk Console Go back in time to the fun days of punk music and the Atari console.