LED in a circuit with alternating polarities


#1

Hello.

I am builing a project that simplified is a dolly moving on a track.
When the dolly reaches the end of the track, it triggers a microswitch that cuts the power to the motor, and redirects the power to a LED to light up to indicate that the switch has been triggered.

My problem is that since the motor controller I am using changes the polarity of the motor to make it go left or right, I am getting positive and negative voltage every other time. (depending on if the dolly is moving right or left).
I have tried to use a 12V relay to trigger and light the LED, but the problem with that is that the relay needs at least 6 volts to latch, and when the motor is running slow, the motor controller only provides 3-4 volts.

Is there anyone that has a sollution on how I can make this work? I am just starting to fiddle with electronics, and I am on a bugdet with this build, so therefore: Is there a relatively easy fix for this problem? Are there relays out there that has a latch range from 3V to 12V?

Attatched is:
1: Schematics of the circuit with the LED (and resistor) connected directly to the microswitch. The problem here is that every other time the positive and negative switches.

2: Schematics of the circuit with a relay attatched to the 2nd output of the microswitch. The problem here is that the relay need 6 volts to latch, and the motor controller doesnt provide that at slow speeds.


#2

@croyfer

Have you thought about using a DPDT switch? Then you would have your LED and your Motor on two separate circuits that would be activated by the same switch. You would also not have to worry about the voltage or polarity for your LED as it will always be constant.

If you have the part number for the micro switch you are using than it may be possible to cross to a DPDT option.