[sdiy] Simple, single supply VCA

[Justin Owen]

Thanks all,

I've read about people using the LM13700 with a single supply - but I've never seen a schematic using it. Can I presume that I'd just follow the same steps as I would for adapting a dual supply op amp schematic to single supply - i.e. send the negative supply pin to GND and bias any inputs to VCC/2 (or whatever)?

Can i presume that you're all using the VCA circuit that I seem to remember being in the 13700 datasheet or is there something better about?

I'm going to tuck the embarrassing question in right about here... Some of you referred to the *two* transistor MS20 VCA... on the schematic if Q19 (C945 Selected) is the first transistor - where's the second?

For the record - my description of a *single* transistor VCA wasn't a typo - but I did say I'd had mixed results!

J

-----Original Message-----
From: Paul Perry [pfperry at melbpc.org.au]
Received: 04.02.2010 01:23:10
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Simple, single supply VCA

I've had the LM13700 work fine as a VCA on 9v,
with (as Karl says ) the right biassing.

I suppose the minimalist approach is the two transistor 
setup in the MS20, though it is noisy (in my opinion)
and I think you have to select the transistors, never fun.

Some ideas in this thread at electromusi9c forum
http://electro-music.com/forum/topic-33190.html&postorder=asc
includig links to Jurgen Habile's applications.

paul perry Melbourne Australia

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