Bob, Most of these cables use the DTR (pin 4 on a DB-9) and RTS (pin7 on a DB-9) lines (Data Terminal Ready and Ready To Send) on most com ports these are configured to be high (5-15v). There is not much current here, just a few mA.
Here is a good article entitled "Get power out of a PC RS-232 Port: http://www.tkk.fi/Misc/Electronics/circuits/rspower.html Here is a link to a good universal programmer that I use on occasion: http://www.cqham.ru/uniprog2_eng.html This works VERY well and like it's name implies VERY universal. The only addition I made was to add another diode to the input matrix from an external power supply. This was for those computers with poor serial ports and no power available from the radio being programmed. I simply used a 78L05 voltage regulator instead of the one listed. It's not low dropout, but it seems to wok fine. Good Luck, Scott Scott Zimmerman Amateur Radio Call N3XCC 474 Barnett Rd Boswell, PA 15531 ----- Original Message ----- From: "Bob M." <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, April 05, 2008 2:51 PM Subject: [Repeater-Builder] RIB-less cable circuitry > Does anybody know of schematics for RIB-less cables? > I'm trying to find out which pin(s) they use to get > power from the serial port to operate the circuitry > built into the DB9 connector body. > > I've got a couple that seem to be dead on two > computers but run fine on another one and I suspect > some very slight differences in the serial port > configurations when the machines are booted up. > > If you have links for such schematics, just post those > rather than the entire image which won't make it > through Yahoo's e-mail system. > > Thanks. > > Bob M. > > > > ____________________________________________________________________________________ > You rock. That's why Blockbuster's offering you one month of Blockbuster > Total Access, No Cost. > http://tc.deals.yahoo.com/tc/blockbuster/text5.com > > ------------------------------------ > > > > Yahoo! Groups Links > > > > > > -- > No virus found in this incoming message. > Checked by AVG. > Version: 7.5.519 / Virus Database: 269.22.5/1359 - Release Date: 4/4/2008 > 8:23 AM > >
