The circuit is intended for carrying out harmless experiments with high-voltage pulses and functions in a similar way as an electrified fence generator. The p. r. f. (pulse repetition frequency) is determined by the time constant of network R1-C3 in the feedback loop of op amp IC1a: with values as specified, it is about 0. 5 Hz. The stage following t
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he op amp, IC1b, converts the rectangular signal into narrow pulses. Differentiating network R2-C4, in conjunction with the switching threshold of the Schmitt trigger inputs of IC1b, determines the pulse period, which here is about 1. 5 ms. The output of IC1b is linked directly to the gate of thyristor THR1, so that this device is triggered by the pulses. The requisite high voltage is generated with the aid of a small mains transformer, whose secondary winding is here used as the primary. This winding, in conjunction with C2, forms a resonant circuit. Capacitor C3 is charged to the supply voltage (12 V) via R3. When a pulse output by IC1b triggers the thyristor, the capacitor is discharged via the secondary winding. The energy stored in the capacitor is, however, not lost, but is stored in the magnetic field produced by the transformer when current flows through it. When the capacitor is discharged, the current ceases, whereupon the magnetic field collapses. This induces a counter e. m. f. in the transformer winding which opposes the voltage earlier applied to the transformer. This means that the direction of the current remains the same. However, capacitor C2 is now charged in the opposite sense, so that the potential across it is negative. When the magnetic field of the transformer has returned the stored energy to the capacitor, the direction of the current reverses, and the negatively charged capacitor is discharged via...
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