The phototransistor is a semiconductor light sensor formed from a basic transistor with a transparent cover that provides much better sensitivity than a photodiode. It is basically a 3-layer semiconductor device which has a light-sensitive base region. The base senses the light and converts it into the current which flows between the collector and the … Read more
Fig. NTC Thermistors (source: ussensor.com) Thermistors These are the thermally sensitive resistors. The resistance of a thermistor varies as a function of temperature. The thermistor is also called thermal resistors. It is a resistive temperature transducer. Thermistors are composed of semiconductor materials. It is composed of a sintered mixture of metallic oxides such as Mn, … Read more
Fig: LVDT cross-section (source: te.com ) Linear Variable Differential Transformer (LVDT) is an inductive transducer that we discussed in the previous article. It is basically used to translate linear motion into electrical signals. LVDT Construction LVDT consists of one primary winding and two secondary windings. All these windings are wound on a cylindrical former. … Read more
Fig. Strain Gauges (source: omega.com) Strain gauge A strain gauge is an electrical transducer which is used for measuring mechanical surface strain. Basic Principle of Strain Gauge When stress is applied to the metal conductor, its resistance changes owing to change in length and cross-sectional area of the conductor. The resistance of the conductor under … Read more
Fig. Thermocouple (source: sterlingsensors.co.uk) What is a Thermocouple? A thermocouple consists of a pair of dissimilar wires joined at one end. It is an active transducer. On the other hand, RTD and thermistors are passive transducers. Thermocouple work on the principle of Seebeck effect. According to Seebeck effect, if two dissimilar metals are joined together … Read more
Piezoelectric Transducer A piezoelectric transducer is one that can generate a voltage proportional to the stress applied to it. These transducers work according to the piezoelectric effect. When a mechanical force or pressure is applied across the piezoelectric crystal, an electric potential appears across the surfaces of crystal. This generation of electric potential is due … Read more
Hall Effect Transducers Hall Effect Transducers are the transducers which work on the principle of hall effect. According to hall effect, if a conducting material strip carries current in the presence of a transverse magnetic field; an EMF is produced between two edges of the conductor in a direction perpendicular to both the magnetic field … Read more
A transducer is a device which, when actuated transforms energy from one form to another. Here input quantity is non-electrical quantity. The output quantity may or may not be electrical quantity. When the output quantity is electrical, then transducer is called as Electrical Transducer. An electrical transducer is a device which converts any physical quantity … Read more
Fig. Capacitive transducers (source: directindustry.com) Capacitive Transducers The capacitive transducer is the capacitor with variable capacitance. The capacitive transducer consists of two parallel metal plates that are separated by the dielectric material such as air. We are familiar with the equation of capacitor which is given as In a normal capacitor, the … Read more
You have heard about proximity sensors in your daily life that are commonly used in mobile or smartphones, tablets, etc. Proximity sensors are commonly used on mobile devices to detect if someone is in nominal range. A proximity sensor is a type of sensor which is able to detect the presence of nearby objects without any … Read more
