# Polarity reversing

#### Xjsport95

Joined May 8, 2016
5
I'm trying to build a circuit using relays to run a motor until it hits a limit switch, when act aged again it will run the opposite direction until it hits the limit switch... It's activated by a single positive pulse... All at 12v system... I have a setup to allow it to run until it hits the switch just having a problem getting it to switch directions... Any help would be greatly appreciated.

#### Colin55

Joined Aug 27, 2015
519
If the motor can be used to click a switch or move a slide switch, the following circuit can be used:

If the train cannot physically click the slide switch in both directions, via a linkage, the following circuit should be used:

When power is applied, the relay is not energised and the train must travel towards the "up limit." The switch is pressed and the relay is energised. The Normally Open contacts of the relay will close and this will keep the relay energised and reverse the train. When the down limit is pressed, the relay is de-energised.
If you cannot get a triple-pole change-over relay, use the following circuit:

#### Xjsport95

Joined May 8, 2016
5
If the motor can be used to click a switch or move a slide switch, the following circuit can be used:

If the train cannot physically click the slide switch in both directions, via a linkage, the following circuit should be used:

When power is applied, the relay is not energised and the train must travel towards the "up limit." The switch is pressed and the relay is energised. The Normally Open contacts of the relay will close and this will keep the relay energised and reverse the train. When the down limit is pressed, the relay is de-energised.
If you cannot get a triple-pole change-over relay, use the following circuit:

Would that allow it to remain energized until it hits the limit from a single 12+ pulse? And if pulsed again would change direction?

#### Xjsport95

Joined May 8, 2016
5
The up limit is no and the down limit is nc ?

#### AnalogKid

Joined Aug 1, 2013
8,832
For both switches you connect to the common and normally closed terminals. For each direction, the switch sits there closed until the traveler hits it, opening the contacts and stopping the motor.

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