power source v dc to be supplied to the inductor inherent in the transformer like in fig4 b the active filter here is in the context of an energy pump thus like the diode d1 the thyristor served to clamp the primary to the power source by only for a selected time also a single rectifying device d1 39 is used at the secondary side for passing energy to the load at times and to interrupt the connection with the load at other times finally a voltage v o is obtained which by accumulation of energy into the transformer and subsequent transfer to the secondary side can be made larger than n 2 n 1 v dc the output is regulated by seecting the instant at which thyristor th1 is turned on the inductor of fig5 is formed by the two primaries n1 of two transformers having a common secondary n2 in this second embodiment rectification by diode d1 39 at the secondary side is used to charge a capacitor c2 in parallel with the load however a viable mode of operation exists in which capacitor c2 can be dispensed while maintaining the overall function of the pump and of the active filter the operation of the energy pump.