This sensitive circuit was found in the August 1971 issue of Radio Electronics magazine. The SCR is equivalent, and the transistor may be a BC548. The load may be a relay.
Although it is a common configuration today, this circuit was taken from an old publication. The...
This configuration was found in an English magazine from 1965. It is valid for any junction FET. The...
The circuit in the figure is an amplifier with gain 10 for alternating signals using the 741. The...