This 1970s RCA circuit can be triggered by light or dark, depending on how the LDR is connected. The controlled load depends on the triac.
Found in an EDN from the 90's this circuit makes use of unusual components today. | Clique na...
Two tone siren (CB9085E) This circuit was found in a 1980’s Radio Electronics. The signal must be...
We found this circuit in a 1986 documentation, however, by the components used it can still be...