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car power supply noise on 12V

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Dec 9, 2008
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power supply noise

hi...i m in serious problem....i m doing a microcontroller based project and my 12 V power supply is very very noisy and it is from the very old fiat car battery. when i start engine on, due to inverted ckt it produces very high ringing noise. The same power supply is the input of my 5V switching regular. so the 5V output is also very noisy. my question is any one suggest me any effective filter ckt for this?????????

power supply noise

To eliminate the noise, you need to install noise supressors for the spark plugs. This will be available with any Automobile spare part dealers. Also you may add 4700Mfd/25volt electrolytic capacitor across the 12 DC line and 2200Mfd/25V across the 5volt line. Hope it helps you. Cheers

Re: power supply noise

What is your board layout like? It is best to build switching power supplies on a single sheet of copper clad board with the component leads as short as possible.

If you have long wires, you will get noise from the switcher itself, get noise induced from your car, noise from Radio Moscow etc etc....

Is the circuit quiet when powered from a bench power supply? this will help tie down where the noise is coming from..

Use good quality capacitors as well (tants)

power supply noise

you can choose 220uF Tantalum capacitors also on the DC Power Lines.
Use an automative grade switching regulator.

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