We found this circuit in an English publication from 1969. The circuit uses transistors from the time and can operate at frequencies up to 300 MHz. Observe the waveforms of the obtained signal.
This circuit was obtained from the Radio Electronics Experimenter magazine in a special edition of 1990....
This circuit was found in a 1980s documentation. It triggers a relay when liquid from a reservoir...
We found this peak audio indicator in a 1980 publication. The M1 indicator can be 200 uA with the...