Switch dashcam based on ignition signal from rear of radio?

[davepusey]

The radio in my car runs from a permenant live, but also receives a 12 volt signal telling it if the ignition is on. This allows it to turn itself off automatically when the engine is stopped and the key is removed.

I wish to use the same signal to do something similar with my dashcam power supply.

This is the circuit I have come up with. The resistor marked LOAD represents the dashcam's power supply. The override switch allows for the camera to continue running when parked in a public please. The LED is part of the switch but has its own independant terminals. With the override switch in the off position, the camera is only running when the ignition is on, and when the override switch is in the on position, the dashcam is running continuously.

Would this work? Thoughts and suggestions please?

 

[JimB]

Try this:

My crude edit of your drawing.

Simpler, less components.

JimB

 

[Nigel Goodwin]

My thoughts exactly JimB.

 

[davepusey]

I can't be sure, but i think the "switched live" is just a control signal, and won't have the current capacity to actually run the dashcam directly, hence the MOSFET.

 

[Nigel Goodwin]

I can't be sure, but i think the "switched live" is just a control signal, and won't have the current capacity to actually run the dashcam directly, hence the MOSFET.

Current requirement of the dashcam should be fairly low anyway, and even 'low' current feeds in cars would be massively more than required - you don't get 'control signals'.

 

[ClydeCrashKop]

If that doesn't have enough power, you can find "switched live" in the fuse box.

 

[davepusey]

Just for completeness I have now studied the wiring diagrams for my car and can confirm the "switched live" for the radio is a 0.5mm2 wire, fed from a 5 amp fuse.

 

[Nigel Goodwin]

Just for completeness I have now studied the wiring diagrams for my car and can confirm the "switched live" for the radio is a 0.5mm2 wire, fed from a 5 amp fuse.

As expected - you don't get low current feeds in cars.