This sensitive circuit was found in the June 1995 Electronics Now magazine. R1 can be from 10k to 1M depending on the desired sensitivity. Power is supplied by the relay.
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...