Hi Roly.

On the Ruby, the F1 and F2 connections are linked together externally to the PLC switch. This means that in the Full,Side and Head positions the +D output from the dynamo is linked directly to the dynamo field winding (marked F2 on both the dynamo and the cutout), and you get full output from the dynamo. In the Half position there is no direct link, and current flows instead from +D to F2 via the half charge resistor within the cutout. The resistor reduces the field excitation current and thereby reduces the charge rate of the dynamo.

If the F1/F2 link is missing and only the F1 connection is made to the switch, the Head position will also exhibit the reduced charge rate.

I suspect the above rather less than intuitive wiring arrangement may be because the PLC switch was used for other applications.

You may like to take a look at my wiring diagram on the technical pages of the Dorset Austin Seven club website.

Hi Roly, There were a few "change over" RNs made with RP features, including the dashboard, in September - October 1932. I have one myself.
Regards,
Ashley

Location: Alford Lincs

Thank you all.
Tomorrow I will bridge the F1 and F2 and see what the result is.

Roly

I strongly commend John Cornworths circuit diagram. Even for those with an electrical background the Austin wiring diagrams are not easy to fathom workings from, and inevitably end up sketching a diagram as Johns.

Note that it does differ in minor detail from some models (sidelight connection, headlight watts, exact resistances etc)

For those of a curious inclination, some other makes had two field resistors and three stages of charge; summer, winter, and lights on. Hence the extra F2 terminals. Equally curious, some makes, like Ford 8, made do with a single rate. With the Seven, winter and lights on are the same rate.

Location: Auckland, NZ

Connecting up F1 and F2 now provides a charge when headlights are switched on.

Thats good and now moves me on to the next issue. I'll create a new post called DEL Dynamo and third brush.

Cheers

Roly