Abstract :
A single-transistor class B oscillator was designed as a gateable transmitter stage for ultrasonic tags. The transmitting efficiency was analyzed by grouping the various losses into two categories: collector circuit losses to determine the collector efficiency; and load circuit losses to determine the load efficiency. The collector efficiency, 58.5 percent for this design, is a function of the internal battery resistance, collector saturation resistance, operating power level, and battery voltage. The load efficiency, 37 percent for this design, includes losses from the transformer, base circuit, and projector. The conditions for maximum power transfer were delineated, and a simple procedure for obtaining an approximate measure of projector efficiency was prepared.
