inductor 80 and winding 91 will pass therethrough in oscillatory fashion the benefit of bipolar timing switch q a and q b may be appreciated by examining the base to emitter voltage waveforms v be of q a and q b illustrated as waveforms h and j each having an amplitude of 7 volts during conduction of q a the base to emitter voltge v be will drop from 7 volts to zero volts whereas the base to emitter voltage v be of q b will rise from 7 volts to zero volts thereby resulting in a base to base voltage between a and b of 14 volts and q a and q b will simultaneously switch from their off to their on states to turn q1 from its on to its off state transistor q1 will initially be conductive or in its on state as shown by waveform k the base to emitter voltage v be of q1 during its on state will be at 2 volt potential dropping sharply past zero potential level to about 11 volt potential for a short period of time by virtue of point c undergoing these potential changes to turn q1 from its on to its off state and then turning q1 back to its conductive or on state when q a and q b are turned off by virtue of operation of timer 50 the switching logic of the foregoing system may be briefly.