GTO Sawtooth Wave Generator

A simple sawtooth generator using a GTO and a Zener diode is shown in figure.

GTO Sawtooth Generator

When the supply is switched on, the GTO will turn on, resulting in the short-circuit equivalent from anode to cathode. As a consequence the capacitor C will begin to charge toward the supply voltage, as illustrated in figure. As the voltage across the capacitor C exceeds the Zener potential, there will be a reversal in gate-to-cathode voltage resulting in a reversal of gate current. Eventually, the negative gate current will be large enough to turn the GTO off. Now the capacitor C will begin to discharge through resistor R„ because turning off of GTO results in the open-circuit equivalent from anode to cathode. The discharge time will be determined by the circuit time constant T = CR₂. The proper choice of R₂ and C will result in the sawtooth waveform shown in figure. Once the output voltage V_out drops below Zener voltage V_Z the GTO will turn on and the process will repeat.