The electro-mechanical voltage regulator on my Ariel was terminally ill, so I decided to fit an elderly 6 volt positive earth solid state unit of "Podtronics" make that I had salvaged from a BSA undergoing work in progress. It is worthwhile mentioning that this was bolted to the inside of the toolbox of the BSA. I had teporarily connected the unit to see if it worked (which it did beautifully), then made a tidy job of fitting it inside the old reg box. No charge followed the fitting. To cut a long exploratory tale short, I accidentally found out that if I left the reg unit connected but removed from the bike (ie. not connected physically to chassis earth) it worked perfectly as before? Are "Podtronics" meant to be isolated from chassis earth? A voltage check to the alloy casing reveals dynamo output voltage with the engine running, but zero volts when not! Would love to know from someone in the know. Meanwhile my battery is charged.