27 on the secondary side if desired even though isolation of the secondary circuit from the control and drive circuitry is not generally required although the circuit isolation device illustrated in fig1 uses a center tapped winding and two switching elements on both the primary and secondary sides a bridge configuration of four switching elements and a nontapped winding could be substituted on either the primary the secondary or both sides of the circuit this applies to the basic circuit described above as well as to more complex circuits to be described below the control circuit must drive the switching elements such that the elements 16 and 26 are 34 on 34 while the elements 17 and 27 are 34 off 34 and vice versa a further consideration is that the 34 on 34 periods for the elements 16 and 17 must not be allowed to overlap due to the finite switching speeds of these devices if the elements 16 and 17 are on simultaneously the input to the isolator circuit will present a short circuit to the signal source this can be avoided if the control circuit provides a 34 dead 34 time or a brief interval between the turn off of one switching element and the.