Automotive Turn Signal Flasher - Lamp Outage Detection

[abuhafss]

Hi Everybody

I am working on an automotive turn signal flasher circuit.

Basically, the original flasher unit installed in a vehicle has lamp outage detection function i.e. when any of the 3 indicator lamps fail, the flashing frequency is doubled. The flasher circuits available on the web lack this function.

Simply, I am looking to incorporate lamp outage detection function in 555 astable flasher circuit. Shall appreciate your help.

 

[abuhafss]

No response.

I came across this circuit which has a relay to detect load. How about replacing that relay with a transistor or a comparator:

http://nls.net/mp/volks/htm/3-term.htm