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 > > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject > line. > > > 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 MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.