Author Topic: Effect of PT2399 anti-latchup circuit  (Read 353 times)

Pimpom

Effect of PT2399 anti-latchup circuit
« on: July 01, 2020, 11:37:16 AM »
I'm not exactly new to electronics but this is my first foray into echo/reverb.  As a first experiment, I built a simple reverb unit based on the PT2399 and it works as expected - except that, when the unit is switched off while the amplifier is still on, there's a whooshing decaying squeal as the unit powers down (I used a separate regulated supply to test the reverb unit). This doesn't happen if the unit and the amp are turned off at the same time.

The delay control pot has a fixed 2.2k resistor in series to avoid latch-up, but then the minimum delay is around 55 msec. This was also expected. Further reduction of the delay time would need an anti-latchup circuit and I've designed one using a MOSFET.

I could just go ahead and build another unit that includes the anti-latchup circuit but I was wondering if I could save time by making use of other people's experience. Does the PT2399 produce some extraneous sound when it comes on with the anti-latchup circuit?

Pimpom

Re: Effect of PT2399 anti-latchup circuit
« Reply #1 on: July 01, 2020, 12:24:16 PM »
Somehow I failed to notice that there's a "Building your own stompbox" section (but saw the Digital & DSP section just below it). Could the mods please move this thread there or is it OK if I just repost it?