This circuit is from an old American documentation from the 70s. Transistor 2N3904 can be replaced by BC548. The relay must have 100 mA of maximum current.
This circuit is from a 1998 Electronics Now and can be easily assembled since it uses a common...
This circuit triggers three incandescent light bulbs following the audio signal applied to its...
This circuit was obtained in the SGS manual of linear integrated circuits of 1982. The components used...