Hi The issue with coax becomes:
Do you want to drive a terminated line? On a board built for a single application, you likely know the answer to that and can design appropriately. On a general purpose board, you probably need to allow for the “worst case” configuration ( = terminated). No, that’s not a recommendation that one operate that way, only a recognition that a lot of people *do* operate that way. Bob > On Dec 12, 2020, at 11:59 AM, Matthias Welwarsky <time-n...@welwarsky.de> > wrote: > > On Samstag, 12. Dezember 2020 14:40:11 CET Bob kb8tq wrote: >> Hi >> >> If you are going to drive much with the timepulse output, you will need to >> buffer it. This is true for just about any practical length of coax. It also >> applies to other cables once they get past the “few inches” range. >> >> Ideally the coax buffer would be something like 4 or so ‘125 buffers in >> parallel, each with a 200 ohm resistor in series with their output. Is it >> going to put out 3.3V or 5V logic? …. > > A HCT125 should have 3.3V logic compatible inputs and TTL outputs. There are > nice dual-instance buffers available, 74AHCT2G125 for example. But this is > not > "breakout board" material any more. > > > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
