SOLID-STATE VOLTAGE REGULATOR

Nowadays, the skills to set up a traditional 3-relay voltage regulator are becoming forgotten. But it is not always necessary, or even preferable, to convert a loco from dynamo to alternator when a solid state dynamo control regulator is readily available.

Developed to resolve a problem on one of my son's locomotives four years ago, this regulator has now been applied to Hudswell Clarke, Planet and Ruston locomotives and has applications elsewhere.

Compared to the voltage regulator it replaces the current rise is smoother and seems to start 'earlier' as the output voltage rises, it needing less voltage to flow through the protective power diode than to operate the older series relay. Since the excitation is entirely analogue, the output thereafter rises smoothly and progressively, without any undue “spikes” into the battery.

The unit comprises a plastic enclosure (top left of the picture above) with terminations clearly labelled underneath . The unit incorporates a terminal for a warning light, but this is not obligatory. The unit can be mounted on the control bulkhead (as seen above) or remotely in the engine bay – a heat sink for the power diode is installed. The system does however require control of both sides of the field windings which are normally commoned one side within the dynamo, and for this reason needs a minor modification before the conversion and an additional cable running out. This is all work which I can undertake on your behalf.