John Green wrote:
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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If you need a stronger output driver, you could look at what was done in
the TAPR TADD-2:
http://www.tapr.org/kits_tadd-2.html
Schematics are available in the documentation.
My first htought was that the TADD-2 might work with a modified version
of the PIC code to give lower division outputs (5 or 1 MHz). It might
work for generating the 1 MHz, but I think you would still need hardware
for the 10 MHZ to 5 MHz division. For your task, it may be easier to do
it all in hardware as mentioned above.
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