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Buzz in 12v car setup


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I made a 1/8” stereo cable for a dvd player for the kids in the car from scrap cable and connectors. As soon as we tap into 12v power in the car there is a buzz in the audio and whine that follows acceleration. Is there a trick to build into the cable to “lift” or otherwise combat the buzz that occurs that someone here might be familiar with? 

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I haven't heard of that problem in years. Sounds like you are picking up noise from the ignition system. Namely the spark plugs.

 

A couple of things you can do. Use shielded dc wire and an rf choke near the powered device, install spark suppression spark plugs. They cut the rf spray.

 

But maybe your ignition coil is going bad. Is the noise any different when the engine is hot vs cold?

 

If you are driving a 1965 Spyder Corvair i'd say replace the condenser in the distributor as well.

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this problem we are experiencing is in a 2018 vw atlas of all things. There is a 1/8 aux jack input we are tapping into with my cable i made. Scrap mogami and 2x neutrik gold right angle 1/8 trs connectors. Simple but seemingly high quality cabling for the task at hand. The noise is slightly reminiscent of older ipod 1/8” out thru a cassette adapter while cig lighter charging years back - only not as extreme. If the dvd player is running off battery, no problems at all. Car stereo stuff and 12v power has never been my wheelhouse

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You might try an inexpensive car ignition noise suppressor such as this one. When installed across the DC feed on my cart it completely got rid of the induced whine from an IFB100 transmitter. 

IMG_20180430_183137.jpg

However, if hum is the major issue when you're powered from the same source, yours may be more of a ground loop problem. 

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Ground loops occur when there is a difference of potential between multiple points of grounding. While AC hum is one possible result of such a condition, spurrious demodulation of various RF signals can also be a result of these differentials. 

 

After all, RF is part voodoo waiting to making its presence known in unseemly ways. 

 

 

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