This simple latching alarm circuit using CMOS gates was found in the May 1990 Radio Electronics magazine. The supply voltage is dependent on the relay.
The circuit shown in the figure consists of a low voltage dropout (LDO) regulator for 200 mA using...
Found in Popular Electronics from the 90s, this circuit can be used in tachometers. The integrated...
This high impedance circuit uses a 12 V lamp to test voltages in a car. We found it in a Popular...