We like to test the effects of different circuits, in addition to its own development. So we found a simple, few parts built in guitar Overdrive circuit. The first stage is a 2N7000 or BS170 MOSFET, J201 JFET the second circuit. The J201 Drain voltage is 4.5V. The R9 potentiometer to adjust. Variations may be a little higher voltage softer, low voltage rought the voice. Some portions of the circuit is different from the original. Example C1, C2, C3 capacitor value. But that does not noticeably affect the sound. For more information, please visit the original site: http://www.runoffgroove.com/peppermill.html
This is a simple guitar vibrato effect, used to obtain the variation in pitch. The circuit of is fairly simple. The oscillator is a standard transistor circuit, and has been used for this sort of application many times.