Cheap, Easy Light Probe

Step 6 Using it.

Attach the alligator clips to the solar cell and plug it into the microphone jack on your computer. Turn on your oscilloscope program or hit record in Audacity. Then you point the solar cell at any light that is changing. If you're using Audacity, you'll have to zoom in to see anything (see the pictures below).

You could solder the wires directly to the solar cell, but I typically don't. This way I can use my probe with any varying voltage source. Just be careful to keep the voltage low so you don't fry your sound card.

I've done some digging (after some comments, thanks) and found a reference to a 2Vpp voltage limit on a SoundBlaster AWE64 Audio Card. You should probably check your solar cell to determine it's maximum output. If you're concerned it would be a simple matter to include a current limiting resistor. The solar cells I've used are rated for a maximum of 0.5 V and I've had no problems so far.

Reference: http://www.ece.msstate.edu/~hagler/May2001/15/BEGIN.HTM

Examples:
-Any light plugged into alternating current
-Your computer monitor (frequency will equal refresh rate)
-TV remote control. The solar cell should pick up the IR.