This alarm circuit was found in April 1975 Radio Electronics magazine. The circuit uses a 12 V power supply and relay but can be modified to work with other voltages.
This simple radio was found in a Popular Electronics from the 90s. L1 and L2 have 100 turns on a...
This circuit was found in Radio Electronics magazine from the 90's. The circuit is for small NiCad...
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...