The applications of sensors and transducers can be seen in all types of electrical and electronic instruments ranging from fancy gadgets to various plants, display units and so on. But, most people get confused whether a transducer and a sensor are the same thing, or are they different. What do they have in common? In this post we shall discuss about the basic working of the sensor and transducer with respect to each other.

Both the devices are used in electronic and electrical applications and are often encountered by mechanics. As the name implies, a sensor is a device that is used to measure various physical quantities like resistance, pressure, flow, level, humidity and so on and convert them into electronic signals (digital or analog) that can be easily read by the user or any other instrument.

As explained earlier, a transducer is a physical device that is used to convert a physical energy into another so as to gather information or to keep track of its measurement.

People get riddled by both terms as they do not understand why transducers are used in sensors. In a multi-operational device, a transducer converts one energy to another. This converted energy is measured or displayed to the user for other measurements using sensors.
It is confusing to see transducers being used in sensors as contact transducers for detecting energy levels and then converting them into electrical energy so as to be displayed on a screen. About twenty years before, we have seen the application of such transducers in tape heads of cassette players. They were used to transfer the magnetic information by direct contact with the magnetic tape. This data was then converted into electrical signals that were sent to loud speakers and then changed to sound format for the user to hear.

Other transducers that were used commonly were called immersion transducers and paintbrush transducers. Immersion type was used to measure energy in the form of sound, pressure and so on. Paintbrush transducers are also similar to the former, but they operate in air.

The one and only purpose to use a sensor is to convert an energy into a form that is noticeable by the user. To make this happen, a sensor may include a transducer as they are capable  of converting it from one form to another.

The simplest example of  a transducer is a Light Emitting Diode (LED) that converts light energy into its corresponding electrical energy. An example for a sensor is the sensors in bikes and cars that can sense the touch and also activates the sirens.

There are also cases when the sensor and transducer are the same. For example,a bi-metallic spring is used to measure the temperature change, and may well be the entire sensor if a pointer is attached to the bi-metalic spring.