MP3 LED Flasher Schematic
Add a couple of bright white LED's (10000 mcd) to swimming goggles and you've got a cheap strobe capable of photic driving.
Can be fed audio output from an MP3 Player or a PC sound card. Most of these devices can generate 4Hz or lower signal at a high enough amplitude to drive this circuit.
I would think almost any opamp could be substituted...TLC272 only chosen because it was the closest handy.
You can create low frequency wavefors easily using Audacity via Generate Menu ==> Tone... select low frequency (ie: 8Hz), amplitude=1. You can append multiple tone generations to get a range of strobing frequencies. If you select the 'Chirp' option you can create a sweep.
Then export the file as MP3 file and play out PC soundcard or load into MP3 player if you want this to be portable.
Audacity found at: audacity.sourceforge.net/
***WARNING*** Strobic flashing may cause epileptic seizures for predisposed individuals....it's rare but you might want someone around when you use this the first few times.