[time-nuts] +AFs-time-nuts+AF0- Wall Clock that takes 1PPS input

[Bill Beam]

A traditional PPS (a few ms on once per second) will not work here.
The square wave refered to here is at 1/2Hz, on for one second, off for one second.
This is sometimes refered to as a heartbeat pulse.
I use heartbeat amplitude 3-5V and capacitor of 50-100uF electrolytic.
The capacitor is NOT connected in series to the clock motor but is in parallel with the motor.
Yields alternating +/- pulses about 1.5V, 30-50ms.
Just right to drive the clock motor.


On Sat, 4 Jan 2020 18:05:00 -0500, MLewis wrote:

>Neat trick!

>The AA driven quarts clocks obviously use very little current, but I 
>don't know how much.
>When using a PPS to drive such a clock directly:
>- is the current draw enough that one should isolate the PPS signal to 
>the clock so the clock/coil draw doesn't affect the PPS signal being 
>read properly from other devices?

>Thanks,

>Michael

>On 04/01/2020 5:46 PM, Bill Beam wrote:
>> The purpose of the series capacitor is to take the derivative of the square wave.
>> The first derivative of a positive square wave is a short positive pulse at the
>> leading edge followed by a short negative pulse at the trailing edge.


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Bill Beam
NL7F