Strain gauges are used to measure the torque applied by a motor, turbine, or engine to fans, generators, wheels, or propellers. This equipment is found in power plants, ships, refineries, automobiles and industry at large. Power is obtained by measuring the strain and rotational speed on a shaft.

Digital Image Correlation (DIC) is a precise, non-contact, and non-interferometric optical method used for measuring the displacement/deformation of a structural element/material subjected to external loading.

A strain gauge is a type of electrical sensor. It’s primary use is to measure force or strain. The resistance of a strain gauge changes when force is applied and this change will give a different electrical output. Strain gauges use this method to measure pressure, force, weight and tension.

Typical foil strain gauge; the blue region is conductive and resistance is measured from one large blue pad to the other. The gauge is far more sensitive to strain in the vertical direction than in the horizontal direction.

Therefore, to measure the strain, you have to accurately measure very small changes in resistance. For example, suppose a test specimen undergoes a strain of 500 me. A strain gage with a GF of 2 exhibits a change in electrical resistance of only 2 (500 x 10-6) = 0.1%.

Strain Gauge is a passive transducer that converts a mechanical elongation or displacement produced due to a force into its corresponding change in resistance R, inductance L, or capacitance C. A strain gauge is basically used to measure the strain in a work piece.

The active transducer is also called as self generating type transducer. The passive transducer is also called as externally powered transducer. The active transducer does not require any auxiliary (external) power supply. Example of passive transducer is LVDT (linear variable differential transformer).

The Thermistor is a solid state temperature sensing device which acts a bit like an electrical resistor but is temperature sensitive. Thermistors can be used to produce an analogue output voltage with variations in ambient temperature and as such can be referred to as a transducer.

A thermocouple is the category of active transducer that is used for temperature measurement. It is one of the simplest and widely used devices for temperature measurement. Thermistor, a semiconductor device is a type of passive transducer in which variation in temperature causes a corresponding change in resistance.

We have three types of active transducers, which are mentioned below: Piezo Electric Transducer. Photo Electric Transducer. Thermo Electric Transducer….Photo Electric Transducer

• The resistance of the material varies.
• The output current of the semiconductor varies.
• The producing voltage of the semiconductor varies.

Definition: A transducer that changes the quantity of non-electrical to electrical is known as active transducer. The best examples of nonelectrical quantities are pressure, temperature, and the illumination of light.

An LVDT measures displacement by associating a specific signal value for any given position of the core. This association of a signal value to a position occurs through electromagnetic coupling of an AC excitation signal on the primary winding to the core and back to the secondary windings.

The transducer is classified by the transduction medium. The transduction medium may be resistive, inductive or capacitive depends on the conversion process that how input transducer converts the input signal into resistance, inductance and capacitance respectively.

Both a sensor and a transducer are used to sense a change within the environment they are surrounded by or an object they are attached to, but, a sensor will give an output in the same format and a transducer will convert the measurement into an electrical signal.

One of the significant difference between the sensor and the transducer is that the sensor senses the physical changes occur in the surrounding whereas the transducer converts the physical quantity or nonelectrical into another signal or electrical signal.

The active transducer changes the energy without using the auxiliary power supply whereas the passive transducer uses the exterior power supply for the conversion of energy.

The passive transducer produces a change in some passive electrical quantity, such as capacitance, resistance, or inductance, as a result of stimulation. Passive transducers usually require additional electrical energy. A simple example of a passive transducer is a device containing a length of wire and a…

Following is a list of some of the important static characteristics of transducers.

• Sensitivity.
• Linearity.
• Resolution.
• Precision (Accuracy)
• Span and Range.
• Threshold.
• Drift.
• Stability.

A transducer is an electronic device that converts energy from one form to another. Common examples include microphones, loudspeakers, thermometers, position and pressure sensors, and antenna. Among the worst transducers, in terms of efficiency, are incandescent lamps.

Factors that Influence the Choice of a Transducer

• Operating Principle.
• Operating Range.
• Sensitivity.
• Cross Sensitivity.
• Accuracy.
• Environmental Compatibility.
• Reliability and Stability.

A Transducers. A transducer converts some sort of energy to sound (source) or converts sound energy (receiver) to an electrical signal.

A transducer is a device that converts energy from one form to another. Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.).

An electric motor is a type of an electric actuator (see graphic). Thus, an electric motor is a transducer AND an actuator because it converts electrical energy to magnetic energy to mechanical energy or motion.