Hi, You need to check your maths...
:-) Rob K -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali Sent: 03 February 2012 12:55 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE5680 missing PPS soln On Fri, 3 Feb 2012 09:50:52 -0000 "Rob Kimberley" <robkimber...@btinternet.com> wrote: > Mine was a green LED out of the junk box, but I did use 330R in > series. 1k8 seems rather large. Then i'm not surprised that your FE-5680 refused to work :-) Just calculate: 5V supply, approx 2V LED voltage -> 3V over the resistor. 3V/330R = 90mA. As i wrote already, the 74AC240 has it's absolute maximum rating at 50mA. For a general logic output, i wouldn't recomend to draw more than 10mA (as Bob Grant wrote, the lock signal doesn't seem to pass trough the 74AC240). Hence, i would say that 330R seems rather small :-) Keep in mind that you drove circuit at over current for quite a long time. The circuit is most likely damaged (if they dont have an over current limit, which i doubt). If for an unknown reason the lock signal fails in the future, it might be due to this. Attila Kinali -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
