Power supply for an apparatus with standby operation

For power supplies that have an operating mode or a standby mode, it is desirable to minimize the power consumption in this standby mode. Therefore, the power supply of the present invention contains, especially for standby operation, a separate switching power supply (L1, T21, OSC) which has a very low power consumption and over which a main switching power supply (L50, T85, DR, STO) is controlled for normal operation. By using a low input voltage by means of capacitors (C1, C2), the cost of the separate switching power supply is kept very low. During normal operation, the separate switching power supply is synchronized via connections (5, 6). The power supply also includes a protection circuit (OVP), which blocks the driver stage (DR) and the start oscillator (STO) of the main switching power supply for a certain amount of time in the event of an overvoltage. Then the main switching power supply goes up again until it shuts off again in case of an existing overvoltage. Applications arise in particular for television sets and video recorders.