This 6-transistor circuit had excellent sensitivity using germanium transistors. The push-pull stage used two transformers, one drive and one output as we usually find at the time.
This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits...
With the CMOS circuit shown, rectangular signals up to a few megahertz can have their frequency divided...
This sensitive motion sensor with inductive sensor was found in a 90s Elektor. The circuit uses only...