Ford Cougar V6 - is it wired as 'negative earth'?

[MkGriff]

Hi,

Can anyone tall me if a 1999 Cougar V6 is a 'negative earth' vehicle?

Reason for asking, is that I want to purchase an Accumate battery conditioner for someone who owns one of these, and want to purchase the optional cigar ligter adapter, to save having to up the bonnet each time the charger is connected/disconnected.

thanks
MkGriff

[HellDiver]

Everything has been negative earth since the 50's.

[MkGriff]

HellDiver said:

Everything has been negative earth since the 50's.

Thanks very much.

BTW, got any BMC Control-M contracts in the City?

[HellDiver]

doogz said:

HellDiver said:

Everything has been negative earth since the 50's.

Apart from all the cars that are not.

Which don't include a Ford Cougar.

[HellDiver]

OK, everything (except one hoopy Japanese import) since the 50's is negative earth.

Edited by HellDiver on Monday 10th January 14:33

[Petrolhead_Rich]

HellDiver said:

Everything has been negative earth since the 50's.

Not looking at the winners from the Positive Earth Drivers Club show 2005

Few 1980's cars in there!

[catman]

I seem to remember that most of the cars that I had in the 60's were positive earth..

Tim

[davepoth]

Driving a positive earth car is not a requirement of the Positive Earth Drivers Club.

As it turns out, the change was due to silicon based elecronics needing a positive supply and negative ground. One of the first uses of silicon on cars would have been the diode pack on an alternator, which is why the change from dynamo to alternator coincided with the change from positive to negative earth.

So in conclusion, any car with silicon based electronics on it (everything since EFI became standard for certain, and lots of earlier stuff) will be negative earth.

Edited by davepoth on Monday 10th January 19:44

[TheLurker]

MkGriff said:

Hi,

Can anyone tall me if a 1999 Cougar V6 is a 'negative earth' vehicle?

Reason for asking, is that I want to purchase an Accumate battery conditioner for someone who owns one of these, and want to purchase the optional cigar ligter adapter, to save having to up the bonnet each time the charger is connected/disconnected.

thanks
MkGriff

Having taken one apart, and re-wired it, I can confirm that it is definatley a negative earth.

Will need to check to see if the lighter socket is ignition switched though. From memory it isn't.

[tank slapper]

Petrolhead_Rich said:

Positive Earth Drivers Club

I know should not be surprised by the existence of that, but I still am.

[Pigeon]

davepoth said:

As it turns out, the change was due to silicon based elecronics needing a positive supply and negative ground. One of the first uses of silicon on cars would have been the diode pack on an alternator, which is why the change from dynamo to alternator coincided with the change from positive to negative earth.

Sorry, not true. Sounds like you're getting mixed up with the change from germanium to silicon transistors. With germanium it's easier to make transistors as PNP devices, which could be described as "positive earth", whereas silicon is more suited to making NPN "negative earth" devices. The circuit diagrams for radios and stuff, and the chassis polarity, were generally "negative earth" in valve days, then "positive earth" when germanium transistors took over from valves, and then back to "negative earth" when silicon took over from germanium.

But the reason it's like that is that a transistor is a three-terminal device with the input applied between one terminal and a common terminal, and the output taken between the third terminal and the common terminal. Those considerations don't apply to diodes, which are two-terminal devices. It's just as easy to make an alternator positive earth as negative earth - indeed I've converted an alternator from negative earth to positive earth just by remounting the original diode pack - used the positive output to mount it and connected the negative output to an insulated terminal.

I've never seen any convincing explanation for the changeover... the closest anything comes is wibbling about galvanic corrosion of earth connections to the body being less of a problem with one than the other, but all it would really do if it did anything is move the corrosion to a different place, and in practice it doesn't make any difference anyway, they corrode just as well on both systems

[davepoth]

Pigeon said:

davepoth said:

As it turns out, the change was due to silicon based elecronics needing a positive supply and negative ground. One of the first uses of silicon on cars would have been the diode pack on an alternator, which is why the change from dynamo to alternator coincided with the change from positive to negative earth.

Sorry, not true. Sounds like you're getting mixed up with the change from germanium to silicon transistors.

I'm not getting anything confused, I just copied it off a website. Thanks for answering properly!