Poptronics recommends this circuit for use in the car when the headlights are left on. The circuit uses a sensitive relay with contact current according to the headlights.
Found in Raytheon's 1960s transistor circuit manual, this circuit employs the CK722, one of the...
Found in Electronics now, this circuit generates signals given by the formulas next to the...
Found in Popular Electronics from the 90s, this circuit can be used as a warning shield for...