In message
, David
Ryeburn writes
In article
,
BillyBobMarley wrote:
Not to be a smart ass but weren't a lot of the old British cars
equipped with a positive ground? What's up with that?

The electrons come out of the negative end of the battery. The Old Brits
were smart. They didn't want the electrons to jump off of the ends of
the cars, so they tied the positive ends of the batteries to the car
chassis. Except for those cars they exported to Poland ;-) .

In the UK, until around 1970, I think all cars had positive 'ground'. I
would be very surprised if USA cars were any different. I believe that
the reason for this is that it was supposed to reduce corrosion of the
electrical connections.

The change to negative ground seemed to coincide with the introduction
of more equipment with NPN transistors (which were generally designed to
have a positive power feed). For a few years, many car radios had a
polarity switch, and if you moved a radio from your old +ve ground car
to you new -ve ground car, you had to remember to change the switch
over. I recall one works colleague blowing up a rather good radio when
he didn't.

If your car had the old dynamo generator (which once they invariably
did), it was usually very easy to reverse the polarity. To do this, you
simply had to give the field winding of the dynamo a 'splat' of reverse
polarity (which reversed the residual magnetism) and (of course), change
over the battery connections (which sometimes entailed fitting a longer
battery ground cable). As the starter motor was series wound, it still
turned in the same direction.
--
Ian