A Transistorized Cathode-Ray Phase-Sensitive Null Detector

A tuned cathode-ray null detector developed for use with a current transformer test set is described. Apart from the cathode ray tube, the detector is completely transistorized and has been designed to detect signals as low as 20 µV at frequencies of 50, 60, and 400 c/s. The third harmonic is down at least 40 dB from the fundamental.