[sdiy] Room 211... Envelope Follower or Pitch to Voltage on a chip?

[Batz Goodfortune]

Y-ellow Cynthia 'n' all.

At 02:05 PM 7/14/02 -0700, Cynthia Webster wrote:

>This all leads me to ask you fellow friends and Do it Yourselfers -
>If anyone makes a combo pre-amp, envelope follower on a Chip kind'a thing?

An NE571 or 572 will do this. you get two per chip. You basically get a 
precision rectifier and a gain stage which can be configured how you like.

The 571 is simple, relatively cheap but rather noisy. It only has a single 
cap for integration so your attack/decay times etc, are the same. Of course 
you don't have to use it like that and I think in your case, this would be 
more than adequate. But noise might be your enemy here.

On the other hand the 572 is somewhat more expensive. It does not have an 
internal pre-amp so you can use something external and thus less noise. You 
can do that with the 571 too but it's tricky and doesn't always work how 
you need it to. The 572 also has a separate pin for attack and decay caps. 
But you can configure that how you wish.

NSC also "use to" make a few precision rectifier chips as I recall. But 
they're probably obsolete now and long gone. If none of the above appeal to 
you, you might want to take a walk through the maxim cattledog some time. 
They do a lot of the more esoteric analogue. You might find precision RMS 
converters etc, can be pressed into service to your liking. AD also do this 
stuff. (Or use to) Though I suspect this would be an expensive route to follow.

Hope this helps.

Nice performance idea. Did you trash the room afterwards?

Be absolutely Icebox.

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