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 of a publication from the 70's uses a different type of power that we had already...
This circuit, from Motorola's 1993 Linear Interface ICs. The circuit causes a lamp to blink at a...
This frequency corresponds to musical note C3. Frequency accuracy depends on the accuracy of the...