APPARATUS FOR MEASURING AND MONITORING FREQUENCY OF ENGINE POWER-GENERATOR

PURPOSE:To obtain a small high precision frequency measuring and monitoring apparatus, by converting the rectangular wave signal based on the zero crossing of electric power producing voltage to the working proper voltage of a microcomputer by removing the negative component of said rectangular wave signal through a buffer circuit. CONSTITUTION:The zero crossing point of the electric power producing voltage of an engine power-generator is detected by a zero crossing detecting circuit Zc constituted of resistors Ra, Rb, diodes Sa, Sb and an operation amplifier OPa. This zero crossing signal is treated with a diode Sc for removing minus polarity output and a buffer circuit BFb equipped with buffer IC1 for converting the level of positive polarity rectangular signal output coming to the output of the zero crossing signal to the working proper voltage of a microcomputer CPU. In addition, the counting of a clock through a quartz oscillator CR of the period between zero crossings is performed by the computer CPU and, because a time constant circuit is not used, the highly precise measurement and monitoring of the frequency of the engine-power generator is performed by simple and small constitution.