Car Radio Noise Eliminator

SAFETY FIRST

This is absolutely necessary:

1- Disconnect car battery because a small spark might cost you allot

2- Wear safety goggles. Your eyes are far more important than whatever you want to achieve

3- Preferably to wear electrician gloves

Recently changed car alternator (charger motor). New part was costly, so it was agreed to install a rebuilt alternator with only 6 months warranty. Should be enough if the car is not intended to stay in the house longer.

Seems that rebuilt was not a good job. This was causing a buzzing noise into the car radio. It goes faster and slower as you press the accelerator.

This is a common issue in used cars.

trying to buy the noise filter. It was costly also. By doing some research (God bless google again)

1- Toroid coil harvest from any switching or desktop power supply

2- Ceramic capacitors 2 pcs with high voltage rating. I experienced with different values this value worked fine: 105K/450 (which is 1uf with 10% tolerance and 450 Volt rating)

3- soldering iron, wires

solder the circuit as shown above in the simple schematic

One can flip the input- output but must make sure the battery +VE supply goes through the coil to filter the noise

solder them together

pics show from both sides how it is soldered.

It is a good idea to test the capacitors before using them. Some caps die from unemployment & sleeping in your drawer.

take the car radio harness, cut the +VE supply line and connect the filter in between.

do not forget to connect the earth with earth of car.

Make sure to insulate this filter inside a small temperature-tolerant plastic box to avoid any short circuit.

Now turn on the radio and enjoy country music again.