This inductance bridge uses an external audio signal. The circuit is from a Radio Electronics from January 1966. The instrument can be a common multimeter in the lowest current range.
This circuit can generate signals from 100 kHz to 50 MHz depending on the crystal and the...
The circuit in the figure represents a typical application of a phototransistor exciting a relay...
Found in Philips documentation from 1968 this circuit operates at frequencies up to 10 MHz with 76...