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digital timer with output

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skad33

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I am looking for an inexpensive timer with an output pulse. I would like it 12 volt. A digital clock style would be best that I could set to trigger a GM wiper motor to pulse one time twice a day. Any suggestions on where to find one would be appreciated. I am not sure on the amperage of the motor but most are fused at 20 amps.
Thanks
 

MikeMl

Well-Known Member
Most Helpful Member
So you want a pulse lasting about 5sec every 12 hours?
How accurate does the 12 hour period have to be?
 
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skad33

New Member
It doesnt have to be that accurate. Even within an hour would be OK. Also the amperage of the output wouldnt have to be as high as 20 amps as I stated. The 20 amps is to run the motor not just to trigger the module, so lower amperage would be fine.
 

MikeMl

Well-Known Member
Most Helpful Member
Use one of these.

12h=60000s. If you use all 16 bits, you would need an input clock running at a period of 60000/(2^16)=60000/65536=0.9155 sec. You can use the built-in RC oscillator to produce the clock.

You will get a CMOS output which is high for 6 hours; and then low for 6 more hours. Capacatively couple that to the gate of NFET switch. Use an RC time-constant of about 5s between the square wave and the gate so that the Fet is turned on for only ~ 5sec.
 
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