I use a three phase solid state variable speed converter, and am very happy with it, although as supplied, the internal unit was fine, the packaging cr*p. But I rebuilt it - previously it had such superb facilities as being able to switch from full speed forward to full speed reverse without going through stop! I was warned that the DC injection for magnetic braking was capable of causing a 30mA RCD to trip, and so had a 100mA one fitted. Had no problems with that. Peter Chadwick, usually Swindon, this week San Diego. 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.