The invention relates to a supply circuit for a load, and in particular to an electronic ballast for a lamp having such a supply circuit. In order to drive a switching transistor T1 of the supply circuit, a forcing circuit ZS is used which is supplied by the supply circuit. At the start of operation, an oscillation of an oscillator circuit OS, which can preferably serve as an amplifier for the forcing circuit ZS in the continuous operating mode, is used for driving.