Abstract: A system comprising an amplifier for amplifying signals of frequencies less than one kilohertz generated by a vibration sensor and using the amplified signal to amplitude modulate a carrier signal at a frequency in excess of one kilohertz and applying the amplitude modulated carrier signal to a sensor interface circuit.

Abstract: A system comprising an amplifier for amplifying signals of frequencies less than one kilohertz generated by a vibration sensor and using the amplified signal to amplitude modulate a carrier signal at a frequency in excess of one kilohertz and applying the amplitude modulated carrier signal to a sensor interface circuit.

Abstract: A digital tachometer for an internal combustion engine includes a circuit for receiving a pick-up pulse having a frequency related to the rotation speed of the engine and outputting a wave shaped pick-up pulse. This circuit filters the pick-up pulses and regulates the filtered voltage to provide a d.c. output for powering the tachometer. A crystal controlled oscillator and divider provides update pulses at intervals of 1 to 10 seconds and provides sampling pulses at frequencies of 1 to 5 kilohertz. A display counter and driver counts speed pulses indicative of speed between update pulses and latches the count until the next update pulse. A numerical display displays the count currently latched in the display counter. A multiplier/divider recieves the pick-up pulses and divides them by the number of pulses per revolution to provide pulses indicative of the engine rotational speed.