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Old 24th Aug 2010, 12:08 pm   #18
Herald1360
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Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
Default Re: Old car radio - how to change polarity?

Quote:
Originally Posted by Steve_P View Post
The only way to put a positive earth in a negative earth vehicle is to completely isolate the earths of the car and the radio.
But not if you use a polarity converter..... as suggested several times already.

The polarity converter generates an isolated battery voltage supply which can have its positive output earthed, thereby providing the correct negative supply for the radio with its chassis connected to earth in the usual way.

Think of it as a separate battery with its positive terminal grounded, just for the radio, with the advantage that it doesn't need to be periodically recharged.
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