[modeleng] Re: generator bis

John Pagett wrote:
> Patrick,
>
> I used to have a Lucas document that detailed their early alternator 
> systems. I wish I knew where it was......
>
> I can remember some parts of the circuit though.
>
> The three output coils I'm pretty sure are arranged as a star (Y), 
> immediately followed by a conventional 3 phase rectifier ( 6 diodes, 3 with 
> cathodes commoned going to the positive output, three with anodes connected 
> to ground. Each coil then connects to two diodes, one going to ground, one 
> to positive.
>
> The positive output is divided in a potential divider and compared to a 
> reference (I think it was a simple zener). This difference is amplified and 
> used to control a power transistor which was connected to the field coil.
>
> There was another connection from the battery, through the ignition on lamp, 
> which went into the regulator. The current through this connection was 
> important - if the lamp failed, the alternator would not charge (and because 
> the lamp had failed, you didn't know the alternator wasn't doing its 
> stuff!).
>
> The field coil was connected through slip rings, one side to the collector 
> of the series pass transistor, the other side to supply.
>
> There was a huge zener diode to clamp the output if the voltage went too 
> high (presumably on transients).
>
> Why not gut an alternator from a scrapyard?
>
> Alternatively, take a look at this 
> http://www.ortodoxism.ro/datasheets2/0/00jgxpdcxpzdgc4j2qphqea5e8wy.pdf it 
> couldn't be much easier!
>
> Regards,
>
> JohnP 
>
>
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>   
Thanks for this info John!

It sound very like the system I have.
Indeed a 3 phase rectifier
But then the fuzzy area starts.
There is a VCO, that controls a  thyristor ? hybrid? whats it?, that in 
turn chops up the feed to the field coil.
At least that is how it seems.
The whole circuit is embedded in some sort of black/brown "gunk" and 
even of the old one, it is almost impossible to get that of.

The VCO's sensing input seems to come from a separate inductor(or that 
could be feedback)

Slowly I am getting there, the Intel on the pdf was handy (have to flea 
it out some more though)

But in the end, I still believe, that going a step backward is in the 
long run the most stable solution.
And that is by adding a separate exciter.
But being able to get it going again the original way would save me a 
lot of trial and error stuff as I would have the proper parameters to 
start out with.
Thanks for the effort you have taken!

Regards
Patrick
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