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 circuit has a voltage gain of 30 times and passband of 14 MHz. The circuit is from the 1974...
This circuit was found in the August 1973 issue of Radio Electronics magazine. The Darlington...
This circuit was found in an old manual of linear integrated circuits of the 80's. Equivalent...