[sdiy] Is this a comparator?

[Needham, Alan]

I would call it a MAX function ?
Could be done with a couple of diodes, one from input to output,
one from threshold source to output, whichever diode is forward-biassed
will supply the output.
The above will obviously suffer a loss across the diode but that could be
allowed for with a output buffer amp with a preset offset.
Have I seen a commercial module for this ? "analogue logic function" or
something?

Got it ... http://www.cgs.synth.net/modules/index.html#cgs26
Yes, Ken Stone's OR gate !

	Alan


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Derek Holzer
Sent: 31 October 2007 1:34 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] Is this a comparator?


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 # 43:
"Destroy nothing; Destroy the most important thing"
_______________________________________________
Synth-diy mailing list
Synth-diy at dropmix.xs4all.nl
http://dropmix.xs4all.nl/mailman/listinfo/synth-diy

_____________________________________________________________________
The information contained in or attached to this email is intended only for the use of the individual or entity to which it is addressed. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are not authorised to and must not disclose, copy, distribute, or retain this message or any part of it. It may contain information which is confidential and/or covered by legal professional or other privilege (or other rules or laws with similar effect in jurisdictions outside England and Wales).
The views expressed in this email are not necessarily the views of Centrica plc, and the company, its directors, officers or employees make no representation or accept any liability for its accuracy or completeness unless expressly stated to the contrary.

Centrica plc

Registered office: Millstream, Maidenhead Road, Windsor, Berkshire SL4 5GD

Registered in England and Wales No 3033654