Article View: sci.electronics
Article #5817Re: Help Needed: TTL<->RS232 without -12vdc
From: MUNTS PHILLIP A
Date: Sat, 25 Aug 1990 23:21
Date: Sat, 25 Aug 1990 23:21
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In article <7574@scolex.sco.COM>, deanr@sco.COM (Dean Reece) writes...
>
>Hi, I need some help with RS232 drivers/receivers
>I'm building a project that needs a standard RS232 port, but only has
>available supplies of +5, +12, and +24 volts. I thought that I
>might be able to use the 0(GND), +12, and +24 kinda like the +/- 12v supply
>usually called for. I couldn't think of any trivial way to do this,
You could use a charge-pump inverter to generate -10V or so from the
+12V supply. This takes as little as an LM555 and some discretes. I just
use the MAX233 (MAX232 with integrated caps) myself. If you're really lazy,
I once saw a data sheet for a DB25 connector with the MAX232 integrated.
Philip Munts N7AHL
NRA Extremist, etc.
University of Alaska, Fairbanks
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<1990Aug25.232127.4269@hayes.fai.alaska.edu>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!decwrl!hayes.fai.alaska.edu!acad3.fai.alaska.edu!ftpam1References:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!decwrl!hayes.fai.alaska.edu!acad3.fai.alaska.edu!ftpam1 From: ftpam1@acad3.fai.alaska.edu (MUNTS PHILLIP A) Newsgroups: sci.electronics Subject: Re: Help Needed: TTL<->RS232 without -12vdc Keywords: RS232, TTL, level shifting Message-ID: <1990Aug25.232127.4269@hayes.fai.alaska.edu> Date: 25 Aug 90 23:21:27 GMT References: <7574@scolex.sco.COM> Sender: usenet@hayes.fai.alaska.edu (J Random USENET) Reply-To: ftpam1@acad3.fai.alaska.edu Followup-To: sci.electronics Organization: University of Alaska Fairbanks Lines: 16 News-Software: VAX/VMS VNEWS 1.3-4