# CDXL Envelope Filter



## thedwest (Sep 30, 2019)

What goes in the big unlabeled spot on this PCB? I've got everything else I need but couldn't figure out what kind of component goes there. Thanks!








						CDXL Classic Envelope Filter - PedalPCB.com
					

Compare to DOD Envelope Filter 440




					www.pedalpcb.com


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## Jovi Bon Kenobi (Sep 30, 2019)

That's a vactrol. Not sure which specific one though. It's a LED and LDR in a box. It's possible to make your own but you'd need a schematic.


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## Chuck D. Bones (Oct 1, 2019)

Here's a schematic.


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## thedwest (Oct 1, 2019)

Chuck D. Bones said:


> Here's a schematic.


Awesome! Thanks!


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## Chuck D. Bones (Oct 1, 2019)

Too bad PedalPCB doesn't make a Mu-Tron III.


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## Nostradoomus (Oct 1, 2019)

I wonder if you could roll your own version of the vtl5c4/2 with an LED and 2 LDRs wired together to make a 3 legger?

Huh, the beavis  schematic calls for a 5c9 instead. Strange.


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## Jovi Bon Kenobi (Oct 1, 2019)

Smallbear has em for $10. Oof haha


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## Nostradoomus (Oct 1, 2019)

I’d just try the xvive version


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## I Love Music (Oct 13, 2019)

Can we post schematics from other places ? I believe this is very, very close to what you want. Use Xvive Audio VTL5C3/2 Dual Element Opto-Coupler.


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## Chuck D. Bones (Oct 13, 2019)

That johnk schematic has typos.  Turns out the Beavis one is wrong too.  This one looks correct.  The PedalPCB board is wired for true bypass, this schematic is not.


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