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.
This counterphase circuit is from a 1973 publication, and can work with mains voltages or 12 V....
This circuit can be used to directly control direct current loads or higher alternating current loads...
The acquisition of data, from a transducer, so that these data can be converted to digital form...