12V camera cold weather

[john2k]

I have a 12V reverse camera installed on my car. but when weather turns cold the camera stops working until it warms up either later during the day or from driving around and the heat generated by the exhaust fume seems to warm it up after a while.

The body of the camera is conductive, so i'm wondering if i can somehow use some kind of heat generated resistor mounted with heat sinking compound to the body and then have this resistor only activate if the temperature is cold. Any ideas how I can do this?

 

[Electrobrains]

Here is the simplest and cheapest circuit I can think of.

To be able to sense and regulate the temperature, at least the NTC thermistor should be mounted on the same metal piece as the heating resistor.
Preferably also the transistor should be mounted on the same metal to save energy (the transistor will also heat up, especially near the set temperature).

If you don't have room for the power transistor on the same spot, a more efficient version with Schmitt trigger (positive feedback) could be be made by adding another transistor.
Also a cheap IC like the famous NE555 could be used to drive the power transistor, but then you directly have more points to solder.

A PTC thermistor can be used by exchanging places of potentiometer and thermistor. The potentiometer would need an added resistor towards +12V.

The power transistor must be electrically isolated or have the emitter connected to the metal tab.