Fixed resistors
The fixed resistor type is the most common resistor, when people talk about a resistor they most probably mean a fixed resistor. Fixed resistors have a constant resistance value. Different resistor materials are used for fixed resistors. For all resistor types the used materials has influence on the resistor properties like the tolerance, cost and noise. Fixed resistors are available in axial, radial and SMD packages. Microhm Electronics' most resistors are fixed ones.
Variable resistors
A simple potentiometerThere are several variable resistor types, their general property is that the resistance value is adjustable. Most variable resistors are adjusted by mechanical movement (linear or rotary). When they are used as a variable voltage divider, they are called potentiometers. When they are used as a variable resistance to control the current in a circuit, they are called rheostats. Digital potentiometers are controlled electronically instead of by mechanical action. In general variable resistors have a higher tolerance of 20% compared to fixed resistors where 5% is the most common.
Varistors
Disc varistor, redVaristors have a non-linear resistance which is dependent on the voltage over the varistor. Above a certain threshold voltage the resistance of a varistor drops very fast. Different varistor types exist, but nowadays the MOV varistor is the most used type. Their characteristics make them suitable as over-voltage protection devices and they are often used as surge protectors.
Thermistors
A small NTC thermistorThermistors are resistors of which the resistance changes significantly when temperature changes. Different thermistor types exist, the two most common types are the NTC and PTC thermistor. NTC thermistors decrease in resistance when the temperature rises, while PTC thermistors increase in resistance when the temperature rises. Thermistors are often used as temperature sensors or thermal protection devices.
Light dependent resistors
Light dependent resistors or photoresistors show a decrease in resistance when light intensity increases. They are often used to identify light or dark situations and are for example used to switch on street lights in the evening.
Magneto-resistors
The magneto-resistor type can be used to detect and measure magnetic fields. The resistance of a magneto-resistor changes with the magnetic field strength and direction.
All the resistors have their own merits and disadvantages, we choose as per our specific demands for the most cost-effective resistors to achieve win-win business relationship and ever-lasting development.
