Positive Earth?
- Thread starter TBolt
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TBolt said:
Nortons went +ve earth in the early 1950s.
1953 and 1954 for most models.
It was said it was because the forthcoming alternators only had +ve earth rectifiers.
Took Nortons a while to adopt those however.
Didn't Triumph go to alternators in the 1940s.
What did they do for rectifiers - or voltage control ?
It should be pointed out that going +ve earth with a generator and voltage regulator merely involved connecting a different battery pole to earth.
And flashing the generator to suit. Nothing else was required, apart from reversing the connections on the ammeter.
All the components were identical. And reversing the procedure/connections could make it -ve earth again...
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The vehicle positive ground/earth convention probably came from telephone and telegraph practice where this causes less corrosion....but has no advantage on a vehicle that does not have any literal electrical connections to the earth. FWIW there is more on all this at http://lyle.smu.edu/~levine/ee8320/positiveground.pdf
I'm sorry, but that was the most half-baked discussion on +ve and -ve ground I've read in a while.
Not one reply there that would get into any science journal.
If you look at a battery sitting idle, and not connected to anything, one terminal will always corrode, and one stay clean.
Where was that discussed ??
Where is magnetoman when you need him...
Not one reply there that would get into any science journal.
If you look at a battery sitting idle, and not connected to anything, one terminal will always corrode, and one stay clean.
Where was that discussed ??
Where is magnetoman when you need him...
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engineers discovered that with positive voltage on the copper wires, copper wires age quickly, due to electrolysis. With negative voltage on the wires, in respect to ground, ( positive ground) the copper is protected from corrosion. This is referred to as cathodic protection ( remember cathodes & anodes?).
There is a trade-off between pos. ground & neg. ground. You're going to have electrically-motivated corrosion on one set of components or another. Corrosion of electrical components (e.g., wires and connections) is much easier to replace on a vehicle than the bodywork or frame itself. Combine this with the fact that, we're better at protecting wires than we used to be and it makes a lot of sense to run a negative ground.
Something I found elsewhere:
Those components of any direct current (DC) electrical system exposed to the atmosphere corrode at varying rates while current is flowing through that system based not only on their metallic composition but on their relative distance from the positive and negative terminals of the storage battery, with rate of corrosion accelerating in direct relation to proximity to the positive terminal. In other words: the closer it is to the + post, the faster it rots away.
Most early auto systems were positive-grounded so the grounding strap between the battery and the engine block could be considered sacrificial and replaced relatively quickly and easily when it corroded badly enough it could no longer conduct current at an acceptable rate. As electrical systems increased in complexity - specifically including head, tail, stop and parking lights at the extreme corners of the vehicle - engineers began to believe that the metal body panels (mainly fenders) also corroded more quickly on vehicles with positive-ground systems than on those using negative-ground systems, resulting in the trend toward near-universal negative-ground systems worldwide by the end of the 1950s.
Or as wiki says:
The electrical term "earth" or "ground" is a connection that runs through the entire electrical system. It may or may not be connected literally to the soil. When a system is "negative earth", it means the electrical earth has a negative polarity. Power can then be run back and forth using only one wire carrying the positive polarity. Similarly, electrical signals need only one wire. At the destination, the circuit is completed by connecting the "negative" terminal to earth or ground.
Until the 70s, cars were built with either a positive or negative earth, with popular British vehicles being among the last to be built with positive earth. Negative earth was adopted globally by automobile manufacturers for the sake of standardization. It was the introduction of radios in automobiles that may have seen negative earth automobiles being favoured. It was also thought positive earth vehicles rusted quicker.
The US telephone system also uses a positive ground, after starting out with negative ground. However, the trolley cars in Atlanta, Georgia were causing electrical induction interference, which led to the phone cables literally falling apart. Every kind of solution was tried, but they all failed, until as a last resort the phone company flipped the polarity, and it has stayed this way till the present day.
Which ties in the automotive connection, the telephone connection, and the science connection (Rohan).
Dont bring magnetoman int this forum, he has a really bad habit (on more than one forum) mis-quoting vintage books to suit his arguments. I have purchased several of those books to confirm the mis-information . I he will have us think we need to buy an electron microscope & a finish gage to get just the right finish on our ignition points :roll:
There is a trade-off between pos. ground & neg. ground. You're going to have electrically-motivated corrosion on one set of components or another. Corrosion of electrical components (e.g., wires and connections) is much easier to replace on a vehicle than the bodywork or frame itself. Combine this with the fact that, we're better at protecting wires than we used to be and it makes a lot of sense to run a negative ground.
Something I found elsewhere:
Those components of any direct current (DC) electrical system exposed to the atmosphere corrode at varying rates while current is flowing through that system based not only on their metallic composition but on their relative distance from the positive and negative terminals of the storage battery, with rate of corrosion accelerating in direct relation to proximity to the positive terminal. In other words: the closer it is to the + post, the faster it rots away.
Most early auto systems were positive-grounded so the grounding strap between the battery and the engine block could be considered sacrificial and replaced relatively quickly and easily when it corroded badly enough it could no longer conduct current at an acceptable rate. As electrical systems increased in complexity - specifically including head, tail, stop and parking lights at the extreme corners of the vehicle - engineers began to believe that the metal body panels (mainly fenders) also corroded more quickly on vehicles with positive-ground systems than on those using negative-ground systems, resulting in the trend toward near-universal negative-ground systems worldwide by the end of the 1950s.
Or as wiki says:
The electrical term "earth" or "ground" is a connection that runs through the entire electrical system. It may or may not be connected literally to the soil. When a system is "negative earth", it means the electrical earth has a negative polarity. Power can then be run back and forth using only one wire carrying the positive polarity. Similarly, electrical signals need only one wire. At the destination, the circuit is completed by connecting the "negative" terminal to earth or ground.
Until the 70s, cars were built with either a positive or negative earth, with popular British vehicles being among the last to be built with positive earth. Negative earth was adopted globally by automobile manufacturers for the sake of standardization. It was the introduction of radios in automobiles that may have seen negative earth automobiles being favoured. It was also thought positive earth vehicles rusted quicker.
The US telephone system also uses a positive ground, after starting out with negative ground. However, the trolley cars in Atlanta, Georgia were causing electrical induction interference, which led to the phone cables literally falling apart. Every kind of solution was tried, but they all failed, until as a last resort the phone company flipped the polarity, and it has stayed this way till the present day.
Which ties in the automotive connection, the telephone connection, and the science connection (Rohan).
Dont bring magnetoman int this forum, he has a really bad habit (on more than one forum) mis-quoting vintage books to suit his arguments. I have purchased several of those books to confirm the mis-information . I he will have us think we need to buy an electron microscope & a finish gage to get just the right finish on our ignition points :roll:
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One search I followed auto related mentioned corrosion also that solid state transistors (radio) were positive ground and the later version ?? were negative ground.
Most British cars etc were positive ground well into the 1970's. (generator and regulator)
From my experience as far as motorcycles Italian b8ikes were negative earth/ground for who knows how long including my Eldorado which has a Bosch 300w generator belt driven with a mechanical regulator,Ducati's of that same period (1967 to 1975) already had alternators with rectifier/regulators.
Moto Guzzi going that way around 1975.
Most British cars etc were positive ground well into the 1970's. (generator and regulator)
From my experience as far as motorcycles Italian b8ikes were negative earth/ground for who knows how long including my Eldorado which has a Bosch 300w generator belt driven with a mechanical regulator,Ducati's of that same period (1967 to 1975) already had alternators with rectifier/regulators.
Moto Guzzi going that way around 1975.
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e: Positive Earth?
Postby beng » Fri Aug 02, 2013 8:09 pm
skipsoldbikes wrote:
he has a really bad habit (on more than one forum) mis-quoting vintage books to suit his arguments.
Hilarious.
beng
Posts: 549
Joined: Fri Jan 21, 2011 7:01 pm
True story
, Ken from Brightspark caught him twice on the BBF misquoting, I gues he thinks he is the only one with old books :lol:
Postby beng » Fri Aug 02, 2013 8:09 pm
skipsoldbikes wrote:
he has a really bad habit (on more than one forum) mis-quoting vintage books to suit his arguments.
Hilarious.
beng
Posts: 549
Joined: Fri Jan 21, 2011 7:01 pm
True story
, Ken from Brightspark caught him twice on the BBF misquoting, I gues he thinks he is the only one with old books :lol:
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skipsoldbikes said:True story
Better show us.
Skip- some of the stuff in your long post on the previous page here is pretty incredible.
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Hi Triton !
The Magnetoman stuff can bee seen on the Britbike forum for anyone interested. Ken at Brightsparkmagnetos.com was nice enough to put lot of the technical books from that discussion on his website for free, for all to read ; as well as some additional technical papers:
http://www.brightsparkmagnetos.com/libr ... /index.htm
As to the topic, "Positive Earth" It seems different groups changed for different reasons. Some of the reasons may have been incorrect. I just put the information out there for discussion, I am not saying it's right or wrong, but all are published information that can be read from numerous sources. A very interesting topic that there is not one answer that covers all areas , or brands.
The Magnetoman stuff can bee seen on the Britbike forum for anyone interested. Ken at Brightsparkmagnetos.com was nice enough to put lot of the technical books from that discussion on his website for free, for all to read ; as well as some additional technical papers:
http://www.brightsparkmagnetos.com/libr ... /index.htm
As to the topic, "Positive Earth" It seems different groups changed for different reasons. Some of the reasons may have been incorrect. I just put the information out there for discussion, I am not saying it's right or wrong, but all are published information that can be read from numerous sources. A very interesting topic that there is not one answer that covers all areas , or brands.
If you are just going to 'put it out there' willy nilly, without correcting or questioning anything, then we may as well all just tell fishing stories ?
It gets even more complicated in computers - which have both a +5v supply and a -5v supply.
And a common chassis earth.
Figure that one out....
It gets even more complicated in computers - which have both a +5v supply and a -5v supply.
And a common chassis earth.
Figure that one out....
