MOTM

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

Not exactly related to a lag circuit, because a lag circuit maintains (sp) its voltage, whereas what Elhardt wants is something that pops back to zero once the input it steady.

Mathematically speaking, this is a differential, though, yes.  Unfortunately, I couldn't quickly find such a circuit from google.com.  Have you tried asking onthe SDIY list?

--PBr

-----Original Message-----
From: Tkacs, Ken [mailto:ken.tkacs@...]
Sent: Saturday, September 14, 2002 6:26 PM
To: 'motm@yahoogroups.com'
Subject: FW: [motm] future thoughts (Rate of change detector)

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


-----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.

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

Tony writes:

>>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....<<

That's such a simple solution I don't know why I didn't think of it. I'll give 
something like that a try and see if it works. Thanks for the other comments 
too. Now that people are refering to it as a differentiator, I'm sure I have 
one or more schematics in some books for such a thing just incase the above 
doesn't work out.

-Elhardt