Active Varitone Pedal with Induction Switch

[frets]

Hi Guys😸

This is a very simple pedal for an Active Varitone.  I found the diagram on the internet attributed to no one.  It was for bass but I have modified it for guitar.  

Based on an MPF102, I modded the circuit with an induction switch.  This gives the guitarist 10 tone choices on a standard 6-Way Rotary Switch.

It sounds very good but the caps are a little brighter than on a passive Varitone.  You may want to go a little deeper on the caps if you like “more.”  Of course with adjustment to the cap values, it can also be used with a bass.

[reTrEaD]

Hey Cindi, there appears to be an error in your drawing. I reckon that connection between the bottom end of the 1k source resistor (ground) and the bottom of the 10nF capacitor shouldn't exist.

Also if the SPDT is a break-before-make, you should move the lead of left side of the inductor from the upper throw so it shares the pole with the bottom leads of all the capacitors. This will cause a single event to occur when the switch changes position, rather than two events. Less likely to cause a click. Of course, if the switch is make-before-break, this change would not be necessary.

[frets]

Retread😸

Thanks,

I’m okay with passive guitar circuit diagrams but struggle with doing these active circuits. I can draw them “literally” but have a difficult time translating to symbols. Although, I think I just screwed up here.

I’ll redo it and post the corrected.

[frets]

[reTrEaD]

Two other observations, neither of which necessarily requires action.

1 - You probably have enough gain in this circuit but if you desire more, you can place a capacitor in parallel with the 1k source resistor. I reckon 47uF should work well enough.

2 - For a deeper notch or treble rolloff, you can add a resistor immediately after the 100uF capacitor. 100k seems appropriate.

[frets]

Thanks Retread,

I really like your idea for the deeper notch. I’m going to go ahead and do both of your recommendations