Voltage supply for model railway - uses potentiometer to set pulse width to control speed of train

摘要

The voltage supply, for model railways or similar, has a pulsed constant dc voltage whose pulse width is varied by a potentiometer. The supply also contains a polarity reversing switch. The supply consists of a rectifier connected to an ac supply, a voltage stabiliser, a current limiter, a clock generator and a pulsed dc voltage with an output stage giving pulses of given width. The power-controlling potentiometer sets a reference voltage that determines the width of the output pulses and therefore the total power contained in a sequence of such pulses.