Vactrol 'VCA' - make up gain

ianbax · Joined: Apr 20, 2022 Posts: 42 Location: Sheffield, UK

Another daft question from me.

I've got a cool vactrol 'VCA' circuit going using a capacitor to delay the fade of the LED for variable decay. But running my 40106 oscillators through it (5v supply) I seem to lose quite a lot of signal going through the LDR.

Is there a simple amplifier circuit to bring the enveloped signal back up to around 5v?

Not averse to using an op amp but as a lunetta this is single supply.

L´Andratté · Posted: Sat Sep 17, 2022 7:55 am Post subject:

What is needed is a schematic of your vca, to see what´s happening Idea

ianbax · Joined: Apr 20, 2022 Posts: 42 Location: Sheffield, UK

I'm sorry I was so slow to reply and your offer of help. I abandoned that particular design.

It was a just a passive LDR-LED (home made vactrol) but with a fading LED so there was some control over the attack and decay. It worked ok but being passive I ran into problems down the line.