We found this circuit with duty cycle adjustment in the May 1988 Radio Electronics magazine. The source must be symmetrical, and the frequency given by R3 and C1.
This alarm with NO and NC sensors was found in the January 1975 Radio Electronics magazine. The...
This circuit was obtained in the 1990 Motorola Linear Databook. The circuit uses a 139 series...
This circuit uses a 6-bit A / D converter from Philips, and has its output compatible with most...