[time-nuts] Local Solar Time Clock

[Chuck Harris]

Given the relatively low currents needed by the clock
motor, and the relatively high currents that can be
sourced/sinked by the arduino, and the fact that the
motor winding is floating relative to the arduino,
one could probably connect the motor like this:

D0---SomeResistor--MOTOR-----D1

Then, how to describe the way to drive it?

Well, starting out with D0=D1=0,

Set D1=1, then in 0.1 sec set D0=1.

Wait 0.9 sec then:

Set D0=0, then in 0.1 sec set D1=0...

Wait 0.9 sec then:

wash rinse repeat...

-Chuck Harris

Jim Lux wrote:
> On 1/19/14 9:17 AM, Chuck Harris wrote:
>> The usual quartz clock that runs off of a AA cell is a little
>> trickier to drive than you might think.  You need to feed
>> its stepper motor coil with an alternating +1.5V and -1.5V pulse.
>> The pulse follows the rising or trailing edge of a 1/2 Hz square
>> wave.  I have driven them using a series capacitor and resistor
>> to ground...arranged as a differentiator, but I don't recall the
>> part values anymore.
>>
>> You arduino could certainly be made to generate such a pulse using
>> a couple of resistors and a couple of digital outputs in a simple
>> DAC sort of circuit.
>>
>
> Yeah.. that *is* the challenge.
>   Use two outputs and make a sort of "H bridge"