Lightweight borehole temperature measuring equipment for resistance thermometers

摘要: Lightweight equipment has been developed for measuring temperature in deep boreholes with an accuracy to less than 0.01 degC even when the ratio of leakage resistance element is order 10 1. The circuit a modified Wheatstone bridge using four leads compensate automatically series lead resistance, shunt insulation and variations these temperature; this makes possible use very small gauge wires thin on cable. output from amplified by compensated, direct coupled transistor amplifier. strength required support cable borehole now main factor preventing any further reduction diameter weight.