Circuit shown in Figure generator consists of an oscillator, voltage follower, the amplitude of zero, zero shift circuit. Used as a self-balancing recorder running test signal
source, output signal 0 ~ 50mV, 25mV output voltage is continuously adjustable positive and negative zero shift, the Duty Cycle 30 ~ 40Hz. IC1 (555) and VT1, VT2, R1, R2, C composition astable multivibrator, VT1, R1 and VT2, R2 respectively composed of charge and discharge current source. IC2 operational amplifier as a voltage follower used primarily for impedance matching, low impedance output. The output voltage V0 V01-V02, by adjusting the RP1, RP2, can achieve zero amplitude level and migration.