[sdiy] Is this a comparator?

[Barry Klein]

Anyone have an idea as to why my XP system doesn't display the photos on
this site?

Also, my understanding of what is needed here is an active halfwave
rectifier, using an op amp as in Walt Jung's Op Amp Cookbook.

Barry


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Andy Wilson
Sent: Wednesday, October 31, 2007 7:01 AM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Is this a comparator?

How about Ken Stone's Analog Logic circuit

http://www.cgs.synth.net/modules/cgs26_analogic.html

Cheers

Andy

On 31 Oct 2007 at 14:50, Derek Holzer wrote:

> Heya Tom,
> 
> Ok, thought maybe a two-step process. Signal would be audio or
> control, 
> in this particular (primitive) system, they are both considered
> equal. 
> If it's choppy, that's just fine, clicks-and-cuts are part of the
> app. 
> Can you be a bit more specific about the audio switch?
> 
> d.
> 
> ps... new AudioWeevil07 looking sharp! They all sold yet?
> 
> Tom Bugs wrote:
> > Hiya D
> > 
> > Yeah, you want a comparator first and then use the output
> squarewave of 
> > the comparator to open/close an audio switch (4000 series or DG
> one for 
> > decent bipolar).
> > Depending on the app you may need some hysteresis or smoothing on
> the 
> > comparator -- are you treating audio or control signals?
> > 
> > Rocking'n'best,
> > Tom
> > 
> > Derek Holzer wrote:
> >> There's a function I want to implement, but I don't know what to
> call 
> >> it so I can't start researching the right circuit.
> >>
> >> I'd like to compare an incoming voltage with a reference voltage,
> and 
> >> only allow the incoming voltage to pass if it's above the
> reference 
> >> voltage. I do not want to square the signal, I want to pass it 
> >> unaltered so long as it's above the threshold of the reference 
> >> voltage. When the incoming voltage is less than the reference,
> then 
> >> the reference voltage would be passed (or none at all).
> >>
> >> What is this function called? A comparator? A gate? It's not a
> logic 
> >> function, since it doesn't deal with square waves. I imagine it's
> a 
> >> simple op-amp trick...
> >>
> >> thx + best,
> >> d.
> > 
> > 
> 
> -- 
> derek holzer ::: http://www.umatic.nl :::
> http://blog.myspace.com/macumbista
> ---Oblique Strategy # 19:
> "Be dirty"
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---

Andy Wilson
http://www.techman.synth.net
techman at synth.net

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