Mains driven power supply for electrical equipment - has capacitive voltage divider producing start voltage to ensure immediate starting

摘要

The mains power supply, for electrical equipment, has a start circuit, a control circuit determining duty factor and a transformer. A capactive voltage divider (5, 6) is coupled across the output of the full wave rectifier and produces a start voltage for passing to the control circuit (8) to start the power supply. The start voltage is applied to the same input of the control circuit that receives the supply voltage from the transformers secondary winding (13). The supply starts immediately without having recourse to an expensive start circuit.