When thyristor $T_{1}$ is conducting, capacitor C is charged to d.c. supply voltage $E_{\mathrm{dc}}$ through the resistor $R_{2}$ . Now, when $T_{2}$ is triggered, a voltage twice the d.c. supply voltage $E_{\mathrm{dc}}$ is applied to the $R_{1} C$ series circuit so that current through the circuit is,

$$i=\frac{2 E_{\mathrm{dc}}}{R_{1}} e^{-t …