Positive Earth?

That link takes to a range of zeners ?

Lucas themselves put out a -ve earth zener for 1978 or 79 Triumphs, wasn't it.
There is a thread somewhere here about doing this.
(what happens about the warning light assimilator ?).

But is there any advantage in this ?
You then have a non-standard electrical system.
Which is fine if no-one ever has to work on it again...
 
Rohan said:
skipsoldbikes said:
As to the commando & the cathode/anode effect originally debated in the auto industry, your Commando surely has a much lower ampere battery, wouldnt that affect the theory somewhat ?
Does amperage come into it ?? How ??
I'm not aware that my battery is flowing any power other than into the ignition when its running.
And when its parked, the key is off, so the chassis is connected to the +ve of the battery only, no amperage whatsoever.
Or it would go flat.
So any amperage powering corrosion of any form is going to be miniscule ?

skipsoldbikes said:
I assume you are referring to diodes in the alternators, the only real difference between a negative ground alternator and a positive ground alternator IS the direction of the diodes. It is true, the diodes have to be insulated from ground, but that's always the case.

British motorcycle electrics had a zener diode as the voltage control system.
That finned thingy under the tank on Trumpys, and the gold thing bolted to the Z plate on Commandos.
It was +ve earth - and bolted to the chassis, for heat dispersal, so there was no insulating away from that.
I'm not aware that Lucas even had -ve earth zener diodes until the late 1970s - for the Triumph T140E was it ?
And that was the core part of british motorcycle electrics that for a long time DEMANDED that they be +ve earth.
No radios on bikes - unless you have a GoldWing.
Wonder how Police radios got on...

BTW, this is the bit that makes Triumph motorcycles positive earth.
The bronzey looking thingie in the middle is a +ve earth semiconductor, a Lucas zener diode. Its not quite an inch across.
It dumps any excess voltage as heat, above a certain threshold volts (14.2 volts, is it ? Probably need to consult the Manual).
Commandos use exactly the same Lucas part, but fitted to a different heatsink.

Positive Earth?
You might have got your electrics mixed up here the Zener is still a negative earth, as it is earthed to the frame :!: :D
 
Bernhard said:
You might have got your electrics mixed up here the Zener is still a negative earth, as it is earthed to the frame :!: :D

You appear to be mixed up here, as usual, spreading more nonsense.
These days these are available in both +ve AND -ve earth versions.

But the -ve earth version ONLY appeared in 1978 or 1979 was it?, for the T140E.
Before then, they were all +ve earth types.
Lets get this story correct.....
 
bwolfie said:
It was a link to a negative earth zener. the auction must have ended.

You would have to change the rectifier also along with the zener to convert to negative ground so it would be cheaper to do it with a podtronics unit or similar.
 
bluto said:
bwolfie said:
It was a link to a negative earth zener. the auction must have ended.

You would have to change the rectifier also along with the zener to convert to negative ground so it would be cheaper to do it with a podtronics unit or similar.

Aren't generic rectifiers from electronics shops very cheap?
 
Triton Thrasher said:
bluto said:
bwolfie said:
It was a link to a negative earth zener. the auction must have ended.

You would have to change the rectifier also along with the zener to convert to negative ground so it would be cheaper to do it with a podtronics unit or similar.

Aren't generic rectifiers from electronics shops very cheap?

They are but the Lucas zener diode is not....the complete Podtronics units run from $50-60 depending on output, number of phases, etc. and that is what the negative ground zener diodes alone are priced at in the EBay link above

Positive Earth?
 
Triton Thrasher said:
Aren't generic rectifiers from electronics shops very cheap?

If you went this way, rather than the Podtronics, you'd also have to ensure they were rated for enough watts (continuously) to be able to handle the full output from a bike alternator.
Some of them are only rather lightweight thingies, power ability wise.
 
Rohan said:
Triton Thrasher said:
Aren't generic rectifiers from electronics shops very cheap?

If you went this way, rather than the Podtronics, you'd also have to ensure they were rated for enough watts (continuously) to be able to handle the full output from a bike alternator.
Some of them are only rather lightweight thingies, power ability wise.

Looks like 200V 35A ones are common and cheap on Ebay.

http://www.ebay.co.uk/itm/KBPC3502-...al_Components_Supplies_ET&hash=item43bda47a51
 
I've got one of those for my Matchless, +ve earth, with 3 phase alternator and it has done me very well. Just change the earth on it it you want to go -ve earth.
Well not THAT one from ebay but similar one

Hope that helps.
 
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