This simple sensitive circuit was suggested in a July 1992 Radio Electronics issue. The relay is a double-contact changeover relay. Sensitivity adjustment is made at R2.
This configuration, which uses a transistorized circuit in the feedback, provides a logarithmic response...
This receiver uses one of the first transistor types available on the market, the CK722, but it...
Suggested by General Electric in 1967 this circuit generates a single pulse when receiving a light signal...