Here's a fun little circuit that I put together this morning. After seeing so many attempts to make the PT2399 sound as clean as possible, I decided to use one with an extreme amount of fuzz and lo and behold the external parts count becomes much smaller when you have less filtering to worry about!
The chip's input stage is set up as a comparator with the aid of the Vref pin, so that gives us an ultra-amplified, squared-off waveform straight away. This squared signal is also used to modulate the delay time (controlled by a 22K pot - anything higher than this made the delayed signal fall apart when modulated). The chip's output stage used to mix the initial fuzz signal with the delayed/modulated version at a fixed 50/50 ratio.
I've called the delay control "Shambles" because as you turn the pot clockwise not only does the delay increase but also the amount of pitch wobble. At small settings, some interesting effects can be heard such as flanger-style sweeps on sustained chords and doubling. There are some obvious mods that can be done if you want this circuit to have more controls, such as adding a blend pot or ditching the 10nF cap and having your own tone control after the output stage.
Soundclips to follow, once I get the chance to record something - if you're itching to hear it, it doesn't take long to get it set up on a breadboard!
Schematic:
Layout (currently unverified):
