Mains unit with DC-to-DC converter - has primary transformer stage with transistor switch operated in pulsed mode controlled by feedback

摘要

An a.c. mains supply is coupled to a rectifier (3) in the form of a bridge circuit that has the output to an inductance (5), diodes (6,7) and a transistor switch (8) that connects with the primary of a transformer (9) via a load capacitor (12). The transformer has a pair of secondary windings (13,14) coupled to load outputs via diodes and capacitors (36,37). In operation the primary circuit transistor is operated by high frequency pulses from a control circuit that receives feedback to control the frequency. ADVANTAGE - Reduces harmonic content of output.