Cigarbox guitar Pre-Amp


I was inspired by the youtube video on the right to electrify my Cigarbox guitar.  I had done a project in the past where I wired a piezoelectric buzzer directly into some PC speakers but it never did sound that great. I did some searching on the web and found that's Colin's circuit was a basic version and that it could be improved upon namely by adding some Zener diodes to protect the FET from voltage spikes.


Collin's Lab -- DIY Contact Mic (embedded on this page)



Breadboarding the circuit

I first setup the circuit on a breadboard to test and to bias the MPF102 according to these instructions:

*For my particular MPF102 I found that 470 ohms gave me a better reading and switched that for the 560 ohm.



- Add an ON/OFF switch

- Find a phono jack with a larger "beak" that can install in a 1/4" wooden wall

- Change the 220k ohm resistor for a potentiometer to vary the gain