Diode watthourmeter

Claim 1

A diode watthourmeter for measuring a.c. electrical energy consumed by a load, using square-law rectifying circuits, comprising: first and second square law rectifying circuit means, each of said first and second square law rectifying means, including an input point and an output point, a plurality of diodes series connected with said input point and having intermediate connection points, a plurality of resistor means each having first and second terminals said first terminals of said plurality of resistor means being connected to a corresponding one of said intermediate connection points, said second terminals being connected together to said output point, first and second transistors having their emitters connected to a respective group of said plurality of series connected diodes of said first and second square law rectifying circuit means; a.c. circuit means connecteD to the input point of said first square law rectifying means to apply thereto a voltage which is the sum of a first voltage equal to the a.c. voltage of the load and a second voltage which is proportioned to the current in the load; said a.c. circuit means also being connected to the input point of said second square law rectifying means to apply thereto a voltage which is the difference of said first and second voltages; a capacitor circuit means including a path for flow of a difference current between output points of said first and second square law rectifying means, and comprising a capacitor connected to receive current pulses from collectors of said first and second transistors in said path for flow of said difference current; and means to measure a frequency of said current pulses, whereby said first and second transistors operate as diodes, and, by virtue of the inherent high collector-base impedance of said first and second transistors of the first and second square law rectifying circuit means, an ideal square law relation is obtained resulting in improved accuracy of electrical energy measurement.