There are many different types of resistor available for use within electronic circuits. These different resistor types have somewhat different properties dependent upon their construction and manufacture. This makes the different types of resistor suitable for different applications.
In the video are show that different size of resistors. We will discuss all possible resistor types one by one in detail and application and there uses.
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1. Linear Resistors.
2. Non Linear Resistors.
1. Linear Resistors:
Those resistors, which values change with the applied voltage and temperature, are called linear resistors. In other words, a resistor, which current value is directly proportional to the applied voltage is known as linear resistors.
Generally, there are two types of resistors which have linear properties.
A. Fixed Resistors.
B. Variable Resistors.
A. Fixed Resistors:
As the name tells everything, fixed resistor is a resistor which has a specific value and we can’t change the value of fixed resistors.
Types of Fixed resistor.
Carbon Composition Resistors:
A typical fixed resistor is made from the mixture of granulated or powdered carbon or graphite, insulation filler, or a resin binder. The ratio of the insulation material determines the actual resistance of the resistor. A plastic coat covers the rods with different color codes (printed) which denote the resistance value. They are available in 1 ohm to 25 mega ohms and in power rating from ¼ watt to up to 5 Watts.
Wire wound Resistors:
Wire wound resistor is made from the insulating core or rod by wrapping around a resistive wire. The resistance wire is generally Tungsten, manganin, Nichrome or nickel or nickel chromium alloy and the insulating core is made of porcelain, Bakelite, press bond paper or ceramic clay material. They are available in the range of 2 watts up to 100 watt power rating or more. The ohmic value of these types of resistors is 1 ohm up to 200k ohms or more and can be operated safely up to C.
Thin Film Resistors:
Basically, all thin film resistors are made of from high grid ceramic rod and a resistive material. A very thin conducting material layer overlaid on insulating rod, plate or tube which is made from high quality ceramic material or glass.
There are two further types of thin film resistors.
1. Carbon Film Resistors.
2. Metal Film Resistors.
Thick Film Resistors:
The production method of Thick film resistors is same like thin film resistors, but the difference is that there is a thick film instead of a thin film or layer of resistive material around. That’s why it is called Thick film resistors.
There are two additional types of thick film resistors.
1. Metal Oxide Resistors.
2. Cermet Film Resistors.
3. Fusible Resistors.
B. Variable Resistors:
As the name indicates, those resistors which values can be changed through a dial, knob, and screw or manually by a proper method. In these types of resistors, there is a sliding arm, which is connected to the shaft and the value of resistance can be changed by rotating the arm. They are used in the radio receiver for volume control and tone control resistance.
Following are the further types of Variable Resistors.
Potentiometers:
Potentiometer is a three terminal device which is used for controlling the level of voltage in the circuit. The resistance between two external terminals is constant while the third terminal is connected with moving contact (Wiper) which is variable. The value of resistance can be changed by rotating the wiper which is connected to the control shaft.
Rheostats:
Rheostats are a two or three terminal device which is used for the current limiting purpose by hand or manual operation. Rheostats are also known as tapped resistors or variable wire wound resistors. To make a rheostats, they wire wind the Nichrome resistance around a ceramic core and then assembled in a protective shell. A metal band is wrapped around the resistor element and it can be used as a Potentiometer or Tapped Rheostat.
Trimmers:
There is an additional screw with Potentiometer or variable resistors for better efficiency and operation and they are known as Trimmers. The value of resistance can be changed by changing the position of screw to rotate by a small screwdriver. They are made from carbon composition, carbon film, cermet and wire materials and available in the range of 50 Ohms up to 5 mega ohms. The power rating of Trimmers potentiometers are from 1/3 to ¾ Watts.
2. Non Linear Resistors:
We know that, nonlinear resistors are those resistors, where the current flowing through it does not change according to Ohm’s Law but, changes with change in temperature or applied voltage.
Following are the additional types of Non Linear Resistors.
1. Thermisters.
2. Varisters (VDR).
3. Photo Resistor or Photo Conductive Cell or LDR.
Thermisters:
Thermisters is a two terminal device which is very sensitive to temperature. In other words, Thermisters is a type of variable resistor which notices the change in temperature. Thermisters are made from the cobalt, Nickel, Strontium and the metal oxides of Manganese. The Resistance of a Thermister is inversely proportional to the temperature, i.e. resistance increases when temperature decrease and vice versa.
Varisters (VDR):
Varisters are voltage dependent Resistors (VDR) which is used to eliminate the high voltage transients. In other words, a special type of variable resistors used to protect circuits from destructive voltage spikes is called varisters. When voltage increases (due to lighting or line faults) across a connected sensitive device or system, then it reduces the level of voltage to a secure level i.e. it changes the level of voltages.
Photo Resistor or Photo Conductive Cell or LDR (Light Dependent Resistors):
Photo Resistor or LDR (Light Dependent Resistors) is a resistor which terminal value of resistance changes with light intensity. In other words, those resistors, which resistance values changes with the falling light on their surface is called Photo Resistor or Photo Conductive Cell or LDR (Light Dependent Resistor). The material which is used to make these kinds of resistors is called photo conductors, e.g. cadmium sulfide, lead sulfide etc.
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