Uses and operation of some simple displacement sensors

Sensors are used on a daily basis by just about every type of industrial processed controlled application nowadays. Anything that needs its position monitoring, its displacement measuring or even its location determining now uses some type of electrical sensing device.

There are countless types of sensors now available in a range of different designs to suit different applications. Some applications that these sensors might need to be used in include:

• Quantity of liquid left in a storage tank
• Measurement of a decreasing roll of newsprint to determine roll size
• Location of products on a conveyor system

Displacement sensors

There are a few different types of technology that displacement sensors can use. A simple type of displacement sensor uses the movement of a wiper on a potentiometer. The rotational, linear or angular motion of the wiper changes the resistance of the potentiometer which in turn is converted into an electrical signal which can be used in an electrical circuit.

Capacitive or inductive sensors work by measuring the changes in capacitance or inductance. This can be due to a change in distance between the plates or the shared area of the plates. A variation in the dielectric constant can also be used via a bridge circuit to convert the change into a voltage or current signal.