This biestable touch circuit was found in American 1980s documentation. The circuit must not be powered by a source without a transformer. Sensitivity depends on the 10 M resistors.
This receiver with two common JFETs was found in an old English documentation. The phone is...
This TTL circuit with the 7493 makes the binary count of the pulses sent by a flip-flop with the...
This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common...