This simple metronome, from 1985 documentation uses only transistors and has two settings. For voltages above 6 V, up to 12 V, replace the BC557 with a BD136.
This monostable circuit appeared in Radio Electronics magazine in October 1965. The circuit...
The presented circuit produces the sound of a fireman's siren. In place of the output transformer with...
The circuit shown in the figure was suggested by Maxim (www.maxim-ic.com) based on the DS2786B...