Four-quadrant multiplication with transistors and magnetic cores

THIS paper describes a relatively simple 4-quadrant analogue multiplying circuit which may be built with the use of diodes, transistors, and magnetic cores. Preliminary tests on the first experimental model show accuracy of approximately ±1 per cent (%) of full scale. Two circuits are discussed, one for sinusoidal supply and the other for square wave supply. Each provides a product of two independent voltages with output in the form of d-c pulses which may be averaged or integrated to yield a continuous analogue output. The pulsing d-c output is reversible in polarity depending upon the signs of the input, each pulse being width-modulated proportional to one of the input voltages and amplitude-modulated proportional to the other. The compactness and simplicity of the circuit make it especially attractive for applications of control and instrumentation in systems where the operation of multiplication is required.