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Lucien Nunes · 4th Dec 2013, 4:17 pm

Metrosil products are normally varistors, I wonder whether they are intended to have a tempco that compensates the coil resistance? Will investigate when I get a moment. There's no mention of this in the description of the Tonum regulator in the AP, perhaps we will have to reverse-engineer a solution if your discs are not salvageable. Of course one could sidestep it entirely and make the alternator self-exciting using a modern electronic AVR.

BTW the layout of my set was altered from the original AM spec when converted for use by the NHS for the mobile X-Ray outfits. Various things were removed and relocated, e.g. my fuel tank is under the floor. The autotransformer was only used to provide a low current 400V 3-phase supply, from the 230V delta alternator. For single-phase use it's not needed and mine has also been removed.

4th Dec 2013, 4:17 pm	#6
Lucien Nunes Rest in Peace Join Date: Apr 2008 Location: London, UK. Posts: 2,508	Re: Tonum regulator Metrosil products are normally varistors, I wonder whether they are intended to have a tempco that compensates the coil resistance? Will investigate when I get a moment. There's no mention of this in the description of the Tonum regulator in the AP, perhaps we will have to reverse-engineer a solution if your discs are not salvageable. Of course one could sidestep it entirely and make the alternator self-exciting using a modern electronic AVR. BTW the layout of my set was altered from the original AM spec when converted for use by the NHS for the mobile X-Ray outfits. Various things were removed and relocated, e.g. my fuel tank is under the floor. The autotransformer was only used to provide a low current 400V 3-phase supply, from the 230V delta alternator. For single-phase use it's not needed and mine has also been removed.