We found this circuit in a 1991s PE Hobbyst Handbook. The circuit fires 10 LEDs that can control incandescent lamps according to their maximum current.
Using the LM3909 this circuit was found in the January 1992 issue of Radio Electronics magazine....
This circuit consists of a bass filter that can be used as a subwoofer in a sound system. The...
This circuit uses a photocell as sensor and a sensitive relay according the power supply voltage....