[time-nuts] HP5065A digital clock info
EWKehren at aol.com
EWKehren at aol.com
Wed Sep 28 01:10:10 UTC 2011
Sorry Ed you are wrong. Hp generates a 65 Hz signal that advances the
internal prescaler 49 counts and uses the 1 pps output to stop the 65 Hz
output at count 49 and waits for the internal 1 pps to go to 50 and advance the
second digit one count. Sounds crazy but it works, makes the clock advance
in perfect sync with the internal second generator.
Bert Kehren
In a message dated 9/27/2011 8:16:43 P.M. Eastern Standard Time,
eb at telight.com writes:
The original clock IC is probably OK - I needed to ID it to figure
out how to modify the circuit for new power and interface. I have a
couple of (probably OK) pulled MM5315s also, which could sub with a
slight pinout rearrangement if needed.
After looking at the manual, I realized that I did look at this
series of parts way back, but didn't get the connection because I
thought it would have to be a type that takes 1 Hz input rather than
50/60 Hz. I see now that they were used in the "set" mode, bypassing
the internal divide by 50/60.
The clock module I have is the type with a 555 used as a one-shot for
normal operation, or as an oscillator for fast setting. I think this
is probably the newer of the designs, since it is simpler.
Ed
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