On Thu, 04 Sep 2008 21:16:43 -0700, Tom Van Baak wrote: >>> 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 > >Ah, I see now. It's a 0.5 Hz square wave. Cool. Yes, that looks >like it might work. Has someone tried this on a quartz clock >stepper motor to make sure you reliably get sufficient impulse? >I wonder why no commercial clocks use this trick. > >/tvb >
It works perfectly and reliably. I drive three wall clocks from the 0.5Hz heartbeat of a Brooks Shera controller with 50-100microF in series to each clock. You need a way to reverse polarity to get onto even or odd second. Five $ wall clocks keeping GPS accurate time. > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. Bill Beam NL7F _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
