Modification of Campbell's Arrangement for Measuring Telephone Frequency

Abstract

To measure telephone frequency, the simplest arrangement is that devised by Campbell. But this arrangement is not suitable to measure lower frequ-ency in most cases. It is shown how the original arrangement can be modified to adapt the measurement of frequency which changes over wide range. The generalized frequency bridge is thus obtained and its principle explained. Some special cases of this generalized bridge are found very simple and satisfactory for the purpose. A frequency bridge devised by Edy Valender (A. I. E. E. Nov. 1921) is also one of them.