Originally Posted by Redhatter

I've had a prototype going for about 4 years now. I agree with the original poster, I'm not sure why they aren't more common given they are more or less a mandatory requirement on almost all motorcycles (vintage ones are exempt).

Motorcycles have the same problem that bicycles have, they are narrow, so the positioning has to be thought out. I found mounting the front indicators off the rear view mirrors works well, and I have a top box with the indicators built-in. Prior to the top box, I had the indicators mounted on the sides of a rear basket.

The circuit is a simple NE555 timer chip driving an IRF540N MOSFET and some diode-OR logic, built using dead bug construction. The indicators themselves are standard motorcycle LED indicators on the front, and on the rear I gutted some incandescent lamp holders and mounted LEDs with series resistors in the sockets.