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FW: [motm] future thoughts (Rate of change detector)

2002-09-15 by Tkacs, Ken

This sounds like a differentiator, no? It's kind of the opposite of a Lag
circuit.

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-----Original Message-----
From: elhardt@...
To: motm@yahoogroups.com
Sent: 9/14/2002 3:42 PM
Subject: Re: [motm] future thoughts (Rate of change detector)

As far as future module thoughts, something I'm finding myself needing
is 
something that outputs a voltage based on how fast an input voltage
changes, 
then the output voltage drops back to zero when the input stops
changing. It's 
kind of like an AC detector, getting rid of the DC component. I'm
needing it to 
detect the initial breath of air from a breath controller and also to
eliminate 
the DC portion of the output of my Spacebeam. If anybody ever does a
module 
like this, let me know. I'm trying to think of a way to do it on the
current 
MOTM module line. Maybe I can go through the AC portion of the mixer or 
something.

-Elhardt

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FW: [motm] future thoughts (Rate of change detector)

2002-09-16 by Tkacs, Ken

Yeah, that's what I was thinking, too. Doesn't that make a passive
differentiator? Or do I have my terms screwed up...?

I remember seeing an op-amp circuit in an old Forest Mims book at Radio
Shack, years ago, that showed simple 3- or 4-component integrator &
differentiator circuits, and I thought that the differentiator pretty much
responded ONLY to changes in voltage, while an integrator RESISTED changes
in voltage.

Seems like AC coupling with a big cap or a differentiator circuit should do
the trick, no?

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-----Original Message-----
From: Tony Allgood [mailto:oakley@...] 

Don't you just want a big cap? Something like 1uF non polar may do the
trick. Shove it inside a jack plug in series with the CV line. A bit
crude but it may just work....

Tony