Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.5 $; site uiucdcs Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!seefromline 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> Lines: 8 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.