Showing posts with label LED. Show all posts
Showing posts with label LED. Show all posts

Friday, September 2, 2011

Solid State Flasher for LEDs

The flasher unit (that thing for turn signals and hazard lights) stopped working today. The issue is that I switched to LEDs for the signal lights. These draw much less current than the original incandescent bulbs. When a regular bulb has failed, the flasher unit detects the lower current draw and speeds up the flasher. This is to indicate to the the driver that a bulb is not working. This was the situation ever since I switched to LED bulbs, and it may have contributed to the flasher's failure.



After opening it up, and pricing a replacement, I decided to make a new one. I chose to use the venerable 555 driving two small transistors in parallel to switch the lights.

I made the PCB to solder directly on the base of the failed flasher unit, which I de-soldered from the original PCB. Sometimes the first time is the charm - it worked when installed.








It makes no noise (the clicking was the relay in the original flasher) and it was a little strange at first. Of course, the really odd thing is that LR put the turn signal lever on the left of the steering column - on a right hand drive vehicle!