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 charger for small batteries was obtained from the 1982 Radio Experimenter Handbook. The...
This telegraphy broadcast monitor delivers a signal to a speaker from a unijunction transistor...
This circuit was found in a 1980s documentation. Q1 and Q2 can be BC548 and SCR a TIC106. The...