Here is a very cool optical filter/tremolo by Dead Astronaut. Built and verified today - works perfectly. :)

The Cardinal Harmonic Tremolo is a great tremolo by Jon Patton that is based on the harmonic tremolo effects found on certain Fender amps 1960-1964. "It’s an unusual, and beautiful, combination of mild phasing and amplitude modulation".

I decided to make a layout without the regular IC LFO and use the TAPLFO from Electric Druid insted (as suggested in the schematic). It was easier to make two separate board for the tremolo and LFO. The recommended vactrol VLT5C1 works best in this circuit. The 10K trimmers set the bias for the J201. Just turn them until it sounds good. :)

The TAPLFO board is just a slightly modified version of the stand alone board I did before. Read more about the required HEX code and PIC programmer in my earlier Tap Tremolo post or visit Electric Druid.

This is a very cool and versatile tremolo by Electric Druid. The signal path is taken from the Tremulus Lune, but the LFO is replaced with a digital chip with tons of features: Tap Tempo, 8 different waveshapes (even a random shape!) and a multiplier function. If you are new to digital chips that require code, read more in my Guitar to MIDI post. Have a look at my finished build here.

Read more about this project and download the HEX code or buy the PCB/pre-programmed chip-kit here: http://www.electricdruid.net/index.php?page=projects.taplfo

I also drew up this layout with only the LFO, Figured it might come in handy. For example to modulate the speed of a delay to create some pitchbend/chorusy effects... Hmmm, wonder how that random waveshape will sound. :o) I have not built this one yet, but it should be ok. Hook up A and B to any pot you want to modulate/replace. Use a regular LED and wrap it in heatshrink or tape with the LDR or use a vactrol. I used a  VTL5C3 vactrol in my build.