An instrument for measuring small forces
R Gibson, J Ingham, L. J. Postle · Journal of Scientific Instruments · 1953
This paper describes an instrument suitable for measuring forces over a range from 10 to 12 000 mg weight with a frequency response which is substantially linear up to 100 c/s. The design of the instrument is such that the force is applied to the centre point of a diaphragm. This diaphragm forms one plate of a parallel plate condenser which is in one arm of a high-frequency bridge circuit. The off-balance voltage produced by the variation in capacity of the condenser is amplified, rectified and displayed on a cathode ray tube. Some details of the performance of the instrument are given in the final section.