I am trying to light up some LEDs on my Rustler VXL RC car only when braking/reversing. I found out that on my receiver I have three wires: black(-), red(+), white(+). The one that interests me is the white (signal wire). This wire tells the speed controller to either turn the motor clockwise or anticlockwise.
White wire voltage is as follows. - no throttle: 0.55V - full throttle forward: 0.71V - full throttle reverse: 0.39V
So, when I brake/reverse the voltage drops from 0.55V to some value but no less than 0.39V.
How can I design a system to catch that voltage drop and activate a switch to light up the LED? What parts would I need to buy? And, what's the difficulty level for this?