Wah-ndering about something...

[garcho]

Without presenting your filter design, it's going to be hard for anyone to give you advice on the appropriate envelope follower. Is this for guitar or synth? Analog synth or digital? Op amp multiple feedback filter, gyrator, OTA? There isn't really any such thing as a generic, all-purpose envelope follower.

[jfrabat]

For LM13700, there's the Snow White Autowah.

I have one of those, and I enjoy it a lot

[Mr. Lime]

Did you guys come up with a sufficient working envelope follower to feed pin 2 of the StompLFO?

That's actually something I had searched for a year ago and I'm curious about a circuit.

I would love to build a Mutron Phaser with StompLFO that can be controlled with picking..

[garcho]

I used a stompLFO to control another stompLFO. It never got off the breadboard, which I'm sure isn't exactly shocking. It was nice to have VC of the LFO parameters though, unlimited knob twiddling fun.

I have a stompLFO on the breadboard right now, connected to a LPF, along with a separate envelope detector. They're all just mixed together going into the frequency cutoff, nothing is buffered or anything, just resistors. It sounds amazing. I love hearing the LFO sneak in after the envelope comes down. I debated about having depth, rate or offset control with CV, but I'm already at 8 pots, so I think I'm just going to have a couple jacks for external CV. I'm almost done tweaking it, definitely boxing this one up.

If you just use a standard op amp rectifier envelope detector and buffer it through another op amp that's biased for a 0-5V output, it will work like a charm.

[ElectricDruid]

If you just use a standard op amp rectifier envelope detector and buffer it through another op amp that's biased for a 0-5V output, it will work like a charm.

Which op-amp did you use for this buffering? A lot of the ones I have in the drawer won't go right down to ground, so I'm curious.

Thanks,
Tom

[garcho]

I'm using a bipolar supply, so I guess I shouldn't have said that. Maybe ye olde LM324 can get close to zero? Or TLC27x? Should have kept my mouth shut

[ElectricDruid]

I'm using a bipolar supply, so I guess I shouldn't have said that. Maybe ye olde LM324 can get close to zero? Or TLC27x? Should have kept my mouth shut

Ah, ok. Yeah, bipolar supply makes lots of things much simpler.

There *are* chips that go down to ground, just not any that I've got in my drawer.