I need a voltage/current controlled amplifier for use in a synth project I'm building - or, rather, six of them. Can anyone recommend a good and inexpensive solution?
some pointers to a few ideas:
1. there's the old reliable approach that can be seen in ota app notes - i think national's lm13700 is still available:
http://www.national.com/ds/LM/LM13700.pdf
2. that semiconductor makes vca devices:
THAT Corporation Blackmer IC Voltage-Controlled Amplifiers
3. analog devices has at least a couple of devices that might be worth a look as well:
http://www.analog.com/static/imported-files/data_sheets/SSM2018T.pdf and
http://www.analog.com/static/imported-files/data_sheets/SSM2164.pdf
the lm13700 is fairly inexpensive i think. the others, i have no idea about. since you need more than one, the ssm2164 may be more interesting.
ok, more than a few 🙂
4, 5, and 6. you can visit almost any diy analog synth site and see more ideas, including approaches to build a discrete transistor vca or use analog multiplier devices (good ones cost $$).
as for recommendations, i have used other (older versions) of item 1 (the no longer available CA3080A and NE5517) in analog synth vca modules and been happy with the result.
good luck!
mlloyd1
1. there's the old reliable approach that can be seen in ota app notes - i think national's lm13700 is still available:
http://www.national.com/ds/LM/LM13700.pdf
2. that semiconductor makes vca devices:
THAT Corporation Blackmer IC Voltage-Controlled Amplifiers
3. analog devices has at least a couple of devices that might be worth a look as well:
http://www.analog.com/static/imported-files/data_sheets/SSM2018T.pdf and
http://www.analog.com/static/imported-files/data_sheets/SSM2164.pdf
the lm13700 is fairly inexpensive i think. the others, i have no idea about. since you need more than one, the ssm2164 may be more interesting.
ok, more than a few 🙂
4, 5, and 6. you can visit almost any diy analog synth site and see more ideas, including approaches to build a discrete transistor vca or use analog multiplier devices (good ones cost $$).
as for recommendations, i have used other (older versions) of item 1 (the no longer available CA3080A and NE5517) in analog synth vca modules and been happy with the result.
good luck!
mlloyd1
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An analog 4-quadrant multiplier like the AD633 would work. Depending on your requirements for THD, etc.
~Tom
~Tom
The AD633 costs a mint - someone named "Audiosector is selling 'em cheap on eBay, though.
I found an IC called a CA3080 sold by Small Bear Electronics for $2.50. It seems to be the cheapest option, and has been highly recommended by other synth builders.
VCA-1
It seems that to use it as a VCA, all you need to do is add a highly linear FET to convert voltage to current. Can anyone recommend one?
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