how to build a sensor/receiver that revives green and red light?
i hope you can help me out. i am competing in a roborace (www.roborace.co.za)
we need a sensor that picks up a green light so that the car can start moving forward,
then we also need a sensor that picks up red light in order to stop the car.
i know you can use a normal LED and connect it the wrong why around apparently it can pick up the same color as what the LED is emitting
example: Green Led will pick up green light.
can someone please help me out