Traffic Light Controller

[JohnGalt]

Hello,

I have an old traffic light that I would like to light up.
I would like to build a board that has 1 - 120volt/600Watt input and 3 - 120volt/200Watt outputs. The outputs we shall call A, B and C will each light up a 150 - 200 watt light bulb. Each light bulb will light one at a time starting with A and ending with C. This will operate continuously. The delay between each output will be from .25 seconds to 2 seconds. This design needs to be robust enough to run 24/7/365.

Thank You,
Jim

[Hero999]

It sounds pretty straightforward, what part are you having problems with?

I would consider replacing the lamps with LEDs because they use less power, can be run off a safe/lower DC voltage, last for longer than incandescent lamps (especially when flashed) and turn on/off instantly. I wouldn't recommend having nasty mains voltage anywhere in your circuit, it's much safer to power the whole thing from a PC or laptop power supply.

If you insist on mains, an AC lamp can be controlled with DC power via a TRIAC and an opto-isolator. I'd advise using an opto-coupler with zero crossing as it's easier on the TRIACs and will generate less RF interference. Relays aren't suited to this application because they tend to wear out very quickly when switched at this rate. If you're using mains, there must  be at least 7mm of clearance between the AC side and DC control voltage.

The sequence can be generated using a ring oscillator, a microcontroller or an oscillator with a CD4017.