Penfold Metal pedal

Another cool effect by Robert Penfold. I could not find any info on this one so I made a layout out of pure curiosity. I was expecting a ring mod, but it's actually a cool metallic sounding octave fuzz/distortion with a fairly strong octave up and a weird stutter/tremolo mode (!) depending on how the Bias pot is set.

The only problem with this circuit is that it uses a LM565 chip which is obsolete and can be hard to find/expensive. I didn't discover that until the layout was finished (doh..) so I had to pay around 10€ for five chips from ebay.

Note that the trimmer has a very small sweetspot for the effect to work at all.