The efficiency of any electrical machine is the ratio of the output to input and is generally expressed in per cent. In the case of ignition systems the input power can be supplied from a battery, 115, volt, 400 cycle generator or an engine driven alternator which is integral to the ignition system. Regardless of the input power source, the ignition unit functions to form this power into a spark for the ignition of combustible mixtures. A spark between two electrodes (igniter plug electrodes) is the most acceptable way for igniting a combustible mixture. The wide variation of the combustible mixtures found in the region of the igniter plug electrodes compels manufacturers to provide a wide variation in ignition systems. The design parameters of the ignition system (spark rate per second, spark energy, duration of the spark) are generally arrived at by empirical engine testing. Thus it is very important that means be provided for testing the energy of the spark independent of the final system application.