[EFM] What EFM designs can be run from +9 volt supply?

Rob cyborg_0 at iquest.net
Sat Jul 15 21:12:46 CEST 2000

There are *plenty* of inverter circuits out there, some using a 741 (hi
parts count) to some using 1104-type designs to increase the voltage and
then introduce a new ground point from which to run the original design off

With more simple circuits modifying the original circuit makes sense, but
with some others it might actually be easier just to use a charge pump
method to gain a negative rail and a new ground reference and not have to
worry about the circuit acting strange.

Just my .0002 cents. (Adjusted by the absorption of China's economy, or lack
thereof ;)


----- Original Message -----
From: >>>marjan<<< <urekar.m at EUnet.yu>
To: <efm at xavax.com>
Cc: Synth-DIY list <synth-diy at node12b53.a2000.nl>
Sent: Saturday, July 15, 2000 8:54 AM
Subject: Re: [EFM] What EFM designs can be run from +9 volt supply?

> > > P.S. Tom, a few years back you had sent me a schematic for a
> > > filter that was optimized to work off of +9 volts. I finished
> > > about 80% of the filter, but a new job and moving to a new state got
> BTW, while talking singlesupply vcf6, any advice how to use one opamp
> from lm3900
> norton in place of normal opamp in there? I have a design with one opamp
> from 3900
> left unused and I want to make it vcf6, it runs off 2 9V batterys.
> opamp in vcf6 is standard diff amp, from one tap of ladder goes 100K and
> 10n in series
> to - in of opamp. from other ladder tap goes 10n cap to + input and from
> it 100K res
> to vcc/2 (speaking of single supply version), and 1M res in opamp
> feedback.
> Now, how to change it to acommodate lm3900?
> thanks,
> marjan

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