Practical Perspectives

Proximity Switches

We have seen in the previous topics that electrical circuits and devices we use in our daily lives contain many switches.

• Most of these switches are mechanical using an actuator that is pushed, pulled, or rotated, causing two pieces of conductors to touch and create a short circuit.

• Sometimes, designers prefer to use switches without moving parts to increase the safety and reliability.

• Such switches are called proximity switches.

Proximity switches are initiated by a physical presence near them.

• Distance is the main factor determining their operation.

• They can be a sensor or transducer, an instrument or meter, a gauge or indicator, a recorder and a controller.

• Proximity switches can be capacitive or inductive that means they are based on capacitors or inductors as you are about to discover in this topic and the following one.