Low-cost, battery-operated oscillators and detectors for a.c. bridges
M D Armitage · Journal of Scientific Instruments · 1955
From a brief examination of the effects of stary capacitance in a.c. bridge circuits, it is concluded that battery-powered circuits, isolated from earth, can make unnecessary the use of screened, balanced transformers. The relative merits of sub-miniature valves and transistors are considered, the latter being preferred. Adequate performance is obtainable in this way; an oscillator giving 1.0 V in 1000 Ω and an amplifier which will detect 0.01 mV are described, both being powered by dry batteries. A considerable reduction in cost can be achieved by simple methods of construction.