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Old 23rd Aug 2010, 9:48 am   #9
neon indicator
Retired Dormant Member
 
Join Date: Jun 2010
Location: Co. Limerick, Ireland.
Posts: 1,183
Default Re: Old car radio - how to change polarity?

Either you can change the radio with a built in switch, or you can't.

It's maybe 20 years (more like 40) since cars had dynamos and could be changed to -Ve from +ve or vice versa. I think I may have done this in the mid 1970s (+ve to -ve for a new car radio).

It the radio has no internal switch, you need a DC to DC converter as the aerial and case is very awkward to insulate and you risk shorting the supply.

It would be really bad idea nowadays to swap a car to +ve earth, even if you could. I'd only swap a vintage or classic car to +ve, that was originally +ve and converted to -ve, as part of a restoration.
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