[time-nuts] Driving clocks from 1pps
didier at cox.net
Fri Sep 5 00:24:12 EDT 2008
> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Tom Van Baak
> Sent: Thursday, September 04, 2008 11:17 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Driving clocks from 1pps
> >> 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.
The capacitor gets too large for a commercial watch or clock, silicon is
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