Ferrite beads, car radio wiring?

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mb82

227 posts

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#198068 24-Jun-2016 23:35

I am making a new wiring harness for my car radio. The harness for the old factory radio has what I believe is ferrite beads on two of the 3 power wires, think it's memory wire and switched 12v. Do I need to include ferrite beads on the new harness, what wires should i put them on? Does it matter on the size/shape of the bead?

Wires for the unit are 8 x speaker wires, constant 12v, switched 12v, illumination, antenna and ground. also have aux cord at back of unit

ubergeeknz

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Vocus

#1579899 24-Jun-2016 23:40

won't hurt if you can re-use them, but you shouldn't need them.

richms

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#1579930 25-Jun-2016 07:52

They usually exist only to pass electromagnetic emissions testing, to stop conducted RF noise coming out on the cable.

I always laugh when I see something supplied with a detachable USB cable with one on it, its not like people will always be using that one cable with the device and they are an annoying pain so many people go to the effort of cutting them off anyway.

Richard rich.ms

Aredwood

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#1580100 25-Jun-2016 13:40

Use some decent sized cable for the constant 12V and ground. As all of the modern headunits I have seen use this wire as the main power feed. Prob around 2.5mm2 Even going to 4mm2 could be worthwhile. As you will be using 4X 4ohm speakers. So equivalent of 1ohm. Meaning the headunits internal amplifier will be drawing about 14A peak. Plus the power used by the other circuits in the headunit. So you need a big enough wire to deliver that current with very little voltage drop. This reduces the amount that the internal amplifier clips. So you get better sound quality.