The control unit was designed to operate in two modes, single and repetitive mode. For calibration purposes, the control unit was set to operate in a single mode. A single push button connected to PIC16F84A microcontroller was employed to perform this task. When, the push button is pressed, the microcontroller produced a single 10 μs pulse. This pulse was then triggered a BC547 transistor. The output of this transistor was used to trigger the first avalanche transistor.