Continuously variable DC source - is controlled by pulse width variations within pulse train controlling switching transistor

摘要

A power source provides a continuously variable DC output without the use of potentiometers. The output level is a function of the width of pulses within a continuous train derived from an external source. A constant DC level (3) is derived from any suitable source, i.e. a battery or zener diode (1), it is fed to the non-inverting input of a negative load resistance differential amplifier (4). The output from the amplifier is fed to an orthodox smoothing circuit, this same output point being connected to a reference level via a switching FET or HF bipolar transistor (5) itself being controlled by the incoming pulse stream (16).