Published in a PE Hobbyst Handbook of 1991, this sensor uses an integrated circuit that is unusual today. The circuit is based on a high frequency oscillator.
Found in a 73 magazine for radio amateurs of the 1980s, this circuit uses a dual-gate MOSFET. This...
This is a bridge for the measurement of low value resistances and high values too. The circuit...
This complementary or bilateral emitter follower was found in American documentation from the 90s....