Tom Van Baak wrote: >> I am in the middle of the design of a micro which uses a 10MHz crystal >> to provide a digital clock, but the time is kept in line via GPS using a >> 1pps NCO, which is steered digitally, rather than altering the 10MHz >> oscillator in GPSDO fashion. >> >> The plan was to provide two outputs (biphase) at 1pps to drive slave >> clocks, but in the light of the notes from Brooke and Chuck, I would be >> better off just providing a single output, and use a series cacacitor. >> >> Chuck, I would expect that the 1pps would need to be about 50% duty >> cycle, or at least have a pulse width of 100ms or so. I can imagine a >> clock driven from 1pps with a low duty cycle would sound quite >> different. >> >> 73, >> Murray ZL1BPU > > 50% duty cycle is way overkill, perhaps even harmful. In the > 'scope traces below you can see the IC generates just 50 ms > biphase pulses every second. That's 1/20, or 5% duty cycle.
No Tom, you misunderstand. The 50% duty cycle pulse provides the rising and falling edges. The small capacitor differentiates that to produce a positive going, or a negative going pulse to make the motor move. -Chuck Harris _______________________________________________ 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.