Many electrical devices use momentary switches. They are most commonly used to set a logical HIGH or LOW state
that is read by a microprocessor/integrated circuit. When working with momentary switches, you can wire multiple switches in parallel to create an OR gate
. This lets any of the switches activate the device just like the original would. A magnetic reed switch
can be used in this way so that the circuit can be activated by a magnet as well as the button. When a magnet is brought close to the sensor, two metal contacts inside the reed switch are pulled into contact with each other. This contact acts like a switch and activates the circuit.Warning:
Be aware that some electronics can be damaged by magnets. Keep magnets away from sensitive electronics such as cathode ray rubes (CRT's)
, magnetic recording devices, etc.