I need to turn on power to a 200 ma DC auto mirror/compass when the line voltage reaches 14V DC and turn it off completely when the line drops below 13V DC. I am looking for the simplest circuit to do this that wont drain the auto battery much.
I'm adding a 12v mirror with compass to my Prius. There is a constant 12V (Nominal) source in the dome light that I can easily access but I want to turn off the mirror when the car is not running.
I have measured the "constant On" line to the dome light at 14-14.3Vdc when car is running and 12.1-12.9Vdc with the car off- and this difference is what I'd like to use to energize the mirror/compass.
I know I can snake a new "Ignition on" lead up to the mirror but this is a nightmare to do in the Prius because of the way the trim is designed.
Any ideas will be appreciated.
I'm adding a 12v mirror with compass to my Prius. There is a constant 12V (Nominal) source in the dome light that I can easily access but I want to turn off the mirror when the car is not running.
I have measured the "constant On" line to the dome light at 14-14.3Vdc when car is running and 12.1-12.9Vdc with the car off- and this difference is what I'd like to use to energize the mirror/compass.
I know I can snake a new "Ignition on" lead up to the mirror but this is a nightmare to do in the Prius because of the way the trim is designed.
Any ideas will be appreciated.