As illustrated, 555 and R1, R2, C1 composition astable multivibrator, the oscillation frequency is about 10kHz, duty cycle close to 50%. VT2, VT3 switch as expanding the use of
current use. When the square wave oscillator is high, VT2, VT3 conduction, the LC discharge; is low, L energy storage through freewheeling diode circuit power supply to the load. When overvoltage, DW breakdown, VT1 saturated conduction, c was very low ( 0.7V), 555 reset to stop, play the role of regulator and dynamic balance.