This sophisticated repellent uses a double 555. We find it in an American documentation from the 80's. The circuit can be powered by batteries or source included in the diagram.
This circuit was found in an Electronic Design from 1967. The circuit uses two triacs being T2...
Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz...
This shield from the 60's uses a germanium transistor of the time and a common type of relay of...