diode is used in a gate assisted turn off mode in a resonant circuit commutated switching dc dc converter to convert power from one voltage level to another voltage level a diode allows energy trapped in stray inductances to be delivered directly to the load rather than be dissipated in snubber resistors application_number US 22459981 A description referring now to the drawing and especially fig1 thereof there is shown a switching power supply that converts a relatively low voltage source to a relatively high voltage output a dc source input not shown can be connected to lines 6 and 8 line 6 is connected to one end of inductor 10 the other end of which is connected to the anode of a field controlled thyristor fct 12 line 8 is connected to the cathode of the fct since the fct is operated in the gate assisted turnoff mode a field terminated diode ftd may also be used the operation and design of fct 39 s and ftd 39 s are described in the paper of d houston et al entitled 34 a field terminated diode 34 published in ieee transactions on electron devices vol ed 23 no 8 august 76 pp 905 911 connected in parallel with the fct is a diode 14 having its anode connected to line 8 a commutating inductor 16 and a commutating capacitor 18 are connected in series and across the fct with the inductor connected to the anode of the fct and the commutating capacitor connected to line 8 connected between the commutating inductor and the commutating capacitor is the anode of diode 20 the cathode of diode 20 is connected to.