Low power transmitter

Claim 1

A low power transmitter having power supply means for providing the transmitter with power, voltage regulator means coupled to the power supply means for regulating the voltage provided for the transmitter, oscillator means coupled to the regulator means for providing a time varying voltage as a function of the voltage of the regulator means, sensor means coupled to the oscillator means for receiving the time varying voltage therefrom and for excitation thereof, said sensor means being responsive to changes in a parameter to be sensed and affecting the time varying signal responsive to the change in the parameter, said sensor means further including rectifier means for rectifying the affected time varying signal to provide a D.C. signal as a function of the parameter to be measured, driver means coupled to the sensor means to drive the oscillator responsive to the D.C. signal, low power consumption amplifier means coupled to receive the D.C. signal and to provide a zero based D.C. voltage output signal representative of the parameter to be measured along two wires, said voltage regulator means further comprising voltage reference means for establlishing a stable reference voltage, error amplifier means coupled to the reference voltage means to provide an error signal as a function of the voltage from the reference voltage means and the voltage from the power supply means, and pass element means coupled to receive the error signal and coupled to the power supply to regulate transmitter voltage at a level not substantially greater than ten volts, the voltage regulator means, oscillator means, sensor means, driver means and low power consumption amplifier means providing such D.C. voltage output signal when the power supply means is limited to not substantially greater than ten volts.