Hi RS-232 inputs and outputs *should* be safe when connected to a + or - 12 supply. Often there's some fine print about "external resistance required" down at the bottom of the spec sheet. The print if small enough that the resistors may or may not make it into the final design. Of course there are chips that don't need the resistors ....
Bob On Feb 17, 2010, at 3:03 AM, Robert Atkinson wrote: > Hi Richard, > As the Thunderbolt is wired as DCE (Data Communictions Equipment A.K.A a > modem with data out on pin 2 and data in on 3) Pin 6 would be a more > appropiate choice. It's the "DCE ready" output so should be compatible with a > PC. I don't know what the current draw of the monitor is, but a bit of series > resistance and a series diode to the pin would make it pretty bullet proof. > Worse case would be if you connected it to a item that had pin 6 tied > directly to a "stiff" -12V supply. > > Robert G8RPI. > > --- On Wed, 17/2/10, Richard W. Solomon <[email protected]> wrote: > > > From: Richard W. Solomon <[email protected]> > Subject: Re: [time-nuts] Fluke1 Monitor > To: [email protected] > Date: Wednesday, 17 February, 2010, 0:15 > > > I cut the lead on pin 4 of the RS-232 connector and hooked it to +12 vdc. > That way I eliminate using another supply. Seems to work alright. > > Just need to make sure that pin 4 of the Computer's Serial Port doesn't > have a compatibility problem. (Just means I can't hook up a computer to > the T-Bolt if there is). > > 73, Dick, W1KSZ > > > -----Original Message----- >> From: Mike Naruta AA8K <[email protected]> >> Sent: Feb 16, 2010 4:44 PM >> To: Discussion of precise time and frequency measurement <[email protected]> >> Subject: Re: [time-nuts] ko4bb monitor >> >> >> Thunderbolt PRECISION GPS 10mhz Standard's LED Monitor >> >> I received two from fluke.l 16 days after I sent my PayPal payment. >> >> It was well-packaged and he fit both in one box to save me >> shipping costs. >> >> They came with a DB-9P already soldered on the cable and a >> typical DC power jack. He even included shells for the DB-9P. >> They both powered up fine and started talking with my >> Thunderbolts right away. Current drain is about 75 ma at >> start-up and then falls to 50 ma (13.6 volts). >> >> It's not Lady Heather, but I can monitor my TBolts at a glance >> without tying up PCs. >> >> >> Mike - AA8K >> >> >> Arthur Dent wrote: >>> The display I got from fluke.l (ordered 12-4-09) ran on +5V but the one I >>> got from Amazon had a 3-terminal regulator and would run from 7-20V and was >>> designed for +12V. I just noticed Bob's Ebay listing has been changed to >>> add this note: >>> >>> "because of some reasons,i change one IC on the PCB, >>> so the buyer whom bought the display unit after 2009.12.25 Please use the >>> 9V for >>> the Power supply. 12v also OK." >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
