The circuit is used to provide forward pulses.Pulse width 20 pulse to 1 pulse per second per second (including s from 10 to 100 ms of the rate of change, and by 1 m Ω potentiometer to adjust.Transistors T1 and T2 form a relaxation oscillation circuit.The oscillation frequency depends on C1 and VR1.By a pulse width 47 k Ω (VR2) potentiometer to change.
