. QST . Fig. 1 — The basic Wheatstone bridge (A) andadaptations (B) for use. (C) is a typical practicalcircuit for a bridge with fixed-resistance arms. Ci, C2and C3 in this circuit are blocking capacitors. \ August 1955 11. The simplicity of the hridge is evident from its ap-pearance. The unknown impedance to be measured isconnected to the coaxial jack on the side, and from agrid-dip meter is coupled to the loop at the left. more accurately than resistance at , and caneasily be kept pure at ordinary frequencies,a high order of bridge accuracy becomes differential capac
. QST . Fig. 1 — The basic Wheatstone bridge (A) andadaptations (B) for use. (C) is a typical practicalcircuit for a bridge with fixed-resistance arms. Ci, C2and C3 in this circuit are blocking capacitors. \ August 1955 11. The simplicity of the hridge is evident from its ap-pearance. The unknown impedance to be measured isconnected to the coaxial jack on the side, and from agrid-dip meter is coupled to the loop at the left. more accurately than resistance at , and caneasily be kept pure at ordinary frequencies,a high order of bridge accuracy becomes differential capacitor is a dual capacitor soarranged that as the shaft is turned the capaci-tance of one unit decreases by the same amountthat the capacitance of the other increases; in abridge, the two capacitors become the variableratio arms. The practical form of W2ZEs circuitis shown in Fig. 2, where Ci is the differentialcapacitor. Ci does not use up any of the inputpower, and when a microammeter is used as anindicator, the circuit will operate well from a grid-dip meter source even with loose coupling. The only fussy part of the bridge is the differ-ential capacitor. For compactness and reductionof stray effects this capacitor
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
