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 setting appears other times in this section from other sources. This is from an 80's American...
This digital timer provides timings from 1 minute to 10 hours with indication on a 3-digit...
Signals from 27 MHz to 150 MHz can be produced by this one-transistor oscillator. The frequency...