This is is a PT80 Delay, as designed by Scott Swartz. All the project info is at JD Sleep’s web site, General Guitar Gadgets. On it’s own, this is a really beautiful sounding delay. When I built it, I added a couple little novelties.
The first thing I added was the little toggle switch on the upper right side, above the knobs. It switches in a 47K resistor on lug 3 of the Delay Time pot to give a much longer delay time. Yes, it does give a kind of lo-fi, grainy sound to the delayed signal, but that’s cool. It’s also an easy mod and it takes up very little space.
The other thing I did was to add an effects loop. Here’s a quick sketch of how it works:
The send jack is a mono, closed circuit jack that will break the connection to the return jack when you insert a plug. The DPDT switch (the larger toggle switch on the side of the pedal) selects either the delay line or the straight signal for the effect return. So, if your’e using a fuzz pedal in the effect loop, for example, you can choose between having only the delayed signal effected, or only the straight signal effected.
To demo the effects loop in the audio clips, above, I recorded some using my Buzzsaw! with the effect return switched to the straight signal (clean delay), and some others using my Wavy Gravy with the effect return switched to the delayed signal (effected delay).
With nothing plugged into the effect loop jacks, it doesn’t matter which position the switch is in. But, if you switch it to select the straight signal for the return, and only plug into the send jack (nothing plugged into the return jack), you’ll get the straight signal out of the send jack and the delay signal only (completely wet, no straight signal) out of the main output jack. Maybe cool for a stereo slapback effect.