Switching power supply circuit for supplying direct current voltage to humidity sensor of clothes washing or drying machine, has transformer controlled by control signals generated intermittently by control unit for period of time

摘要

The circuit (10) has a transformer (11) controlled by control signals (PWM1, PWM2) generated by a control unit (12), where the control signals are generated intermittently. The control signals are generated for a first period of time, where the period of time is predetermined so that output voltage (Vout) of the circuit has a constant value. The control signals are not generated for a second period of time. Switching units e.g. transistors (T1, T2) such as MOSFETS, control injection of energy into the transformer. The switching units are controlled by the control signals. An independent claim is also included for an electrical household appliance.