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I am trying to make a 12 volt DC motor start and stop with a timer. It needs to park in the same place every time. I am also using a double pole double throw micro switch.

How can this be accomplished?

JRE
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RH1
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  • Ah, your question is a FAQ (Frequently Asked Question). You might like to gives more details, so we can make suggestions to entertain your situation/application. For example, (1) How precise you want your start and stop positions, ups to 1 cm or 1 mm, 1 degree or 10 degrees? (2) Do you can have any position sensors such as a Hall effect sensor to indicate the position, (3) Do you have any encoder to measure/detect to revolutions maｄe? – tlfong01 Mar 28 '22 at 04:16
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    Do some research and look at how wiper motors are parked, cars, vans & trucks… – Solar Mike Mar 28 '22 at 04:16
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    It is not clear what you want. Do you mean: a timer fires, the motor travels "forward" for a certain time, then goes back to park"? So, two timers? Or what else? Anyway, parking is easy if you use a limit switch. – linuxfan says Reinstate Monica Mar 28 '22 at 07:43

2 Answers2

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Here's the concept.

enter image description here

S1 is the on-off switch.

S2 is a normally-closed limit switch that is actuated by the motor which keeps it open in the 'park' position.

When S1 is closed, the motor starts and S2 closes as it is released. When S1 is then opened, the motor continues to run till S2 opens and the motor parks.

You would need to work on the application of this concept to suit your requirement.

vu2nan
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Using timers for this will be very unreliable, as the motor speed will vary with loading, supply voltage, phase of the moon, and other influences.

The reliable method, used in millions of car windshield wiper systems, andn many other places, is to use a limit switch that opens when the motor reaches the desired stopping location.

Peter Bennett
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  • "...is to use a limit switch..."?

    OP said "I am also using a double pole double throw micro switch." Most "limit switches" are snap-action micro switches. The OP's last edit was 2-hours ago and your comment made 24-minutes ago.

     – GT Electronics Mar 28 '22 at 06:20