# Leprechaun with light-dependent expression controller



## p_wats (Jan 7, 2020)

I built a simple LDR-based expression controller to use with my Synthstrom Deluge, but with a few tweaks it works well with pedals too. Here it is controlling the pitch for my Leprechaun as it mangles a beat from the Volca Sample: 






Here's a gut shot to show how simple it all is: 










It's basically a stereo jack with a toggle to decide which connections go to tip and sleeve (a trick used in the cheap M-Audio expression pedal that I found useful), then an LDR, a 100K pot to adjust sensitivity and a toggle to decide the order of the LDR/Pot (allowing you to decide if light makes the resistance go up or down). Most if it came from a simple image search on how to get an LDR working with Arduino, but that's overkill for simple pedal control.

Lots of fun!


----------



## Dali (Jan 7, 2020)

Not enough skulls.

Seriously, it's fantastic. Now I want to build one (and I got plenty unused 1590B getting dust...).

Could you draw a simple graphic for newbies like me?


----------



## p_wats (Jan 7, 2020)

Thanks! This is the image I started with that will get you going (ignore the Arduino board and replace that with a stereo jack).





Basically, the red and green wires connect to the tip and sleeve of a stereo jack (one of my toggle switches reverses this order, just in case not every expression jack is wired that way). I replaced the resistor with a pot and then added a toggle to switch the order of the LDR and pot, but that's not necessary.


----------

