Using LM3909 integrated circuits, this circuit was found in an American documentation from the 90's. The frequencies can be changed by changing the capacitors.
This circuit is intended to limit the ringing time of a bell. Even if the button is kept pressed for...
We found this circuit in the November 1974 Radio Electronics magazine. The frequency depends on C1...
This conventional 12 V power supply stabilized with 2 A current was found in a 1995 documentation. Its...