A buffer capacitor (1026) shares, via the dump switch (1023), a charge with the rotate capacitor (1022), thereby forming an output value.

A bypass capacitor provides a path for diverting a portion of the power which would otherwise be fed back to the buffer capacitor during low level dimming.

A buffer capacitor (20) is also incorporated in a chip and is recharged to a constant supply voltage during operation.

Said comparator unit activates the control unit until the charging voltage across the buffer capacitor falls below the predetermined desired value.

If the induced current will be rectified, smoothed and stored in a buffer condenser, then it can be considered as the actual energy surplus.

In the event of a voltage collapse on the auxiliary line, the signal input (4) is fed via the buffer capacitor (12) which is dimensioned to buffer the power input (2).

Therefore, the supply voltage VuP remains present (because of the presence of a buffer capacitor (CF) in the absence of the input voltage (Ui).

During these times, the R-78S is powered by a buffer capacitor and consumes only 7µA.

A buffer capacitor (2.20) is arranged between the negative connection of the first DC source (1.1) and the positive connection of the second DC source (1.2).

Consequently, overboost voltages across buffer capacitor during low level dimming are substantially reduced.

According to the invention, a supply current which flows during the pulse pause of said pulse width modulated signals and is dependent on an inductor of the electrical connection lines is taken up by a buffer capacitor.

The buffer capacitor can be connected to the direct voltage branch by a controlled switch (S) when voltage drops in the network or in the direct voltage branch.

A dimmable fluorescent lamp including a feedback circuit for drawing sufficient current to maintain an appropriate charge across the buffer capacitor.

In the event of a voltage collapse on the main line (6), the power input is fed via the auxiliary line or by means of a current flowing from the buffer capacitor (12).

The power supply circuit further preferably comprises a controller that adjusts the charging voltage drop across the buffer capacitor once it has been gradually increased to the desired value.