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From: irwin@uiucdcs.Uiuc.ARPA
Newsgroups: net.micro
Subject: Re: servo computer products
Message-ID: <10400197@uiucdcs>
Date: Tue, 16-Jul-85 10:37:00 EDT
Article-I.D.: uiucdcs.10400197
Posted: Tue Jul 16 10:37:00 1985
Date-Received: Thu, 18-Jul-85 05:34:54 EDT
References: <732@abnji.UUCP>
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Nf-ID: #R:abnji.UUCP:-73200:uiucdcs:10400197:000:435
Nf-From: uiucdcs.Uiuc.ARPA!irwin    Jul 16 09:37:00 1985


It is easy to generate an on board voltage for RS-232. The current drain
is not much, so a 555 timer can be used as an oscillator, a couple of
diodes and capacitors to form a voltage doubler and presto, one 12 volt
supply. This can be done to form a plus or minus supply. Back when the
DRAMS had two voltages, I purchased a 128k memory board that had the
second voltage for the memory chips generated in this fashion. It worked
great.