The input and output jacks are connected by wire between the tips. Between the signal path and ground (the sleeves of the 1/4" jacks) is a 100k photoresistor. The red led is the signal light for the photoresistor and the green light is and indicator light that sits in a led bezel to block it's light from the inside of the enclosure so it doesn't reach the photoresistor. The user is able to use the indicator light as a meter to get a measure of the speed of the tremolo before even playing. Nothing game changing but it's certainly useful and I'm proud of that idea :) let me know what you think in the comments. Email me if you want a vid demonstrating the pedal. Blackironprison.fxpedals@gmail.com
Edit: VERY IMPORTANT! The circuit for the input and output signals and the circuit for the signal light are completely isolated on separate boards. Do not use the same ground point for both circuits or the led will 'click' and create unwanted noise. You can place a 100k pot in series with the photoresistor for 'depth' control.
