This circuit was found in a 1975 documentation. The SCR can be of any type and in this case, we have the horn activation. The relay must be a 12 V type with high contact current.
Found in Popular Electronics from the 90s, this circuit uses a reed switch on the rails as a...
This low input impedance amplifier stage was found in a 1963 documentation. The circuit employs a...
This 2003 circuit uses two types of sensors: by reed-switch and by infrared. If the magnetic...