[sdiy] Comparator = Opamp ??

[Rob]

Well, didn't the Wasp filter kinda do that? I mean, by using 4069UBs to act
as opamps?

BTW, anyone ever build the Wasp filter with opamps instead of 4069s? Just
wondering what effect is has.. BTW, I am actually thinking about redesigning
your wasp filter but adding another two filter stages for a switchable
2pole/4pole config. Don't know if I will do it yet, but I might give it a
shot..

I realize that a good portion of the unique sound of the 4069ubs is what the
Wasp filter is all about, otherwise it seems to be a simple OTA based
filter. I am just curious what kind of mucking up could be had by
mixing/matching opamps and 4069s in a configuration like that and make it
switchable perhaps.

Rob

----- Original Message -----
From: "jh." <jhaible at t-online.de>
To: <peter83 at bigfoot.com>; <synth-diy at node12b53.a2000.nl>
Sent: Tuesday, March 06, 2001 5:43 PM
Subject: Re: [sdiy] Comparator = Opamp ??


> > A comparator is a digital device that outputs a 'high' signal (logic 1
or
> about 4 to 5 Volts), when the voltage on the + connector is higher than
the
> voltage on the - connector. If the one on the + is lower, it outputs a
'low'
> signal (logic 0 or 0 Volts).
> >
> > An Opamp has exactly the same appearance in schematics, though i get the
> impression (from Circuit Maker 2000 (simulation software)) that it behaves
> differently. Can anyone tell me the difference, or state that they infact
> ARE the same...
>
>
> Things have evolved quite a bit since the start, so you have a lot of very
> specialized
> devices, both for opamps and comparators. But in the beginning, a
comparator
> was just an opamp without the compensation capacitor - no dominant pole,
no
> closed loop stability, but much faster than an opamp.
>
> I think I've seen one circuit from Electro Harmonix (the masters of cheap
> design, in any positive sense of the word), where one comparator of a
> quad package is abused as a linear opamp - quite some feedback network to
> get
> it stable, but avoids an extra DIL package for opamps when one comparator
> was unused. Not that such things would be wise nowadays when capacitors
> are more expensive than opamps ...
>
> JH.
>
>