Momentary "expression pedal", PT2399 delay self-oscillation

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Nocentelli
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Post by Nocentelli »

I haven't built a useful DIY pedal in a while, but I recently snagged a Red Witch Violetta delay pedal ("analog" sounding digital) which is pretty nifty. As well as being tiny, cheap and sounding pretty good, it also has a mini expression pedal jack to control the number of repeats whilst playing (e.g. to trigger runaway repeat oscillation). I have an old EV-5 exp pedal, but i decided to knock up a tiny "momentary expression pedal" in a 1590A to kick in the oscillation instead. The 1/8" mini stereo jack on the violetta is simply a switching jack that disconnects the internal repeats pot and uses the expression pedal pot in it's place. The suggested expression pedals in the manual are pretty varied in their pot values, so I just used a 100kB as the "normal" repeats level control and added a 50kA and 2k2 stopper resistor in series with a nice Carling momentary NO switch to short the wiper and hot connection on the normal repeats pot.
schem.bmp
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It's stupidly simple, but it would make a simple addition to any DIY delay pedal build in place of the standard repeats pot as it allows you to set up exactly how long it takes for the self-oscillation to build-up after the switch is first held down. It would also make a decent "two setting" expression pedal with the momentary switch replaced with a latching one, since the two pots can work together to produce a wide variety of different settings.
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modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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