If it helps Bart this is a typical but simplified alternator circuit diagram as the regulator in the field circuit is not shown.
![[Linked Image]](https://www.picoauto.com/images/uploads/case-studies/atl_wiring.png)
The extra set of diodes you queried are to the right and provide half wave rectification of the three phase output to maintain the field circuit, as explained in earlier post. Sometimes referred to as the diode trio, virtually all automotive alternators have such although of lower current rating than the three main pairs of diodes shown top and bottom which provide full wave rectification of the same three phase output, to charge and maintain battery loads.
Some alternators have a pulse terminal labelled W, taken from one of the phases and which can drive a tachometer calibrated to alternator drive ratio.
