[moved] Help - Noise Filtering (power supply)

[Docara]

Hi,

Backgtround-
I need to power a RF and logic switching board from a 12Vdc (automotive based) supply which feeds a water pump motor. The position of my intended project will be approx 2m away and the other side of a metal bulkhead even so I intend to use a FM based modules.

Question-

I don't have a scope available to measure specifics so could someone point me in the direction to help me achieve a clean power line that feeds a 9V regulator.

Thanks

 

[Audioguru]

If your regulator is a 7809 then its input must never drop to less than 10.5V. Then it does not pass any input noise if it has the input and output capacitors recommended on its datasheet.
The input voltage will probably drop to less than 10.5V if the engine starter is used and when the 12V car battery is dead.

I have never seen an electric motor used for the water pump on a car, usually mechanically from an engine belt. if the motor has a fuse then it and its wiring might drop the voltage a little.

Are you FM modulating a radio transmitter with logic signals and receiving it in the car? Then the FM radio receiver might pickup ignition noise.