This is PWM controller I bought for speed control of DC motor:


DC motor rotation direction is controlled using switch: when switch is in position I motor rotates in one direction and when it is in position II motor rotates in opposite direction. Since I need to have limiters also, I removed this switch and shorted controller on this way:


Instead of only motor, I put on output of controller DPDT switch, limiters and motor. It looks like this:


Here is schematic:


Now I can change direction of rotation using DPDT, I have also limiters and of course I can control speed. My question is, is it possible to remotely control direction of rotation instead of manual control using DPDT?

  • \$\begingroup\$ To electronically control a switch, you typically need to know something about the nature of the circuit it is in, particularly for a non-isolated switch made of semiconductors. If you do not know that and cannot deduce it, your options are more limited. A relay whose ratings include the maximum possibility is one way. \$\endgroup\$ May 23, 2016 at 14:55

1 Answer 1


You can either use a DPDT relay, or you can use a different kind of speed controller that uses a "dual H-bridge" where it controls BOTH speed and direction using four transistors.


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