Different Types of Resistors
Resistors are the most commonly used components in electronic circuits and devices. The main purpose of a resistor is to maintain specified values of voltage and current in an electronic circuit. A Resistor works on the principle of Ohm’s law and the law states that the voltage across the terminals of a resistor is directly proportional to the current flowing through it.
The unit of resistance is Ohm. The Ohm symbol shows resistance in a circuit from the name Geog Ohm – a German physicist who invented it.
here are different types of resistors available in the market with diverse rating and sizes. Some of these are described below.
- Wire wound resistors
- Metal film resistors
- Thick film and Thin film resistors
- Network and Surface Mount Resistors
Wire wound Resistors
These resistors vary in physical appearance and size. These wire-wound resistors are commonly a length of wires usually made of an alloy such as nickel chromium or copper-nickel manganese alloy. These resistors are the oldest type of resistors having excellent properties like high power ratings and low resistive values. During their use, these resistors can become very hot, and for this reason these are housed in a finned metal case.
Metal film Resistor
These resistors are made from metal oxide or small rods of ceramic-coated metal. These are similar to carbon-film resistors and their resistivity is controlled by the thickness of the coating layer. The properties like reliability, accuracy and stability are considerably better for these resistors. These resistors can be obtained in a wide range of resistance values (from a few ohms to millions of ohms).
Thick film and Thin film Resistors
Thin film resistors are made by sputtering some resistive material on to an insulating substrate (a method of vacuum deposition), and are therefore more expensive than the thick film resistors. The resistive element for these resistors is approximately 1000 angstroms. Thin film resistors have better temperature coefficients, lower capacitance, low parasitic inductance and low noise. These resistors are preferred for microwave active and passive power components such as microwave power terminations, microwave power resistors and microwave power attenuators. These are mostly used for applications that require high accuracy and high stability.
Surface mount Resistors
Surface mount resistors come in a variety of packages size and shape agreed by the EIA (Electronic Industry Alliance). These are made by depositing a film of resistive material and don’t have enough space for color-code bands owing to small size.
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