[time-nuts] An easy to generate 5, 1 MHz from 10 MHz

John Green wpxs472 at gmail.com
Tue Jul 28 19:28:31 UTC 2009


A cheap and easy way is to use a 74HC14, 74HC390. Capacitively couple the 10
MHz into one of the 6 inputs of the HC14 to square it up, out of that into
one of the divide by 2 inputs of the HC390, that goes to another input of
the HC14 to act as a buffer which provides the 5 MHz output. Next, into the
divide by 5 input of the HC390 to give 1 MHz out. This also goes through one
section of the HC14. There is another section of the HC390 if you wish to
divide down farther. I made one of these to feed an old Marconi service
monitor that requires 1 MHz instead of 10 MHz as an external reference
input. I also have 5 MHz and 100KHz available if I need them. True, the HC14
isn't a proper buffer meant to drive low impedance loads, but it seems to
work OK for me. I laid it out in Eagle and routed out a board with the
T-Tech here at work but there is no reason you couldn't do it with wire on
perf board.


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