Learn Electronic Circuits from ChatGPG - Types of Resistances

 

What are types of resistances?

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There are several types of resistances used in electronic circuits, each designed for specific applications and with unique properties. The main types of resistances include:

1.     Fixed Resistors: Fixed resistors have a predetermined resistance value that cannot be adjusted. They are the most common type of resistors used in electronic circuits and come in various package styles, such as through-hole and surface mount. Fixed resistors are used for setting bias points, current limiting, voltage division, and other general applications.

2.     Variable Resistors (Potentiometers): Variable resistors, often referred to as potentiometers or "pots," allow you to change their resistance value by adjusting a physical control (such as a knob or screw). They are used for tasks like volume control in audio equipment, setting control thresholds, and calibrating circuits.

3.     Thermistors: Thermistors are resistors whose resistance varies significantly with changes in temperature. There are two main types of thermistors:

·         NTC (Negative Temperature Coefficient) Thermistors: As temperature increases, the resistance of NTC thermistors decreases. They are commonly used for temperature sensing and temperature compensation in circuits.

·         PTC (Positive Temperature Coefficient) Thermistors: In PTC thermistors, resistance increases with temperature. They are used for applications like overcurrent protection and motor starting.

4.     Light-Dependent Resistors (LDRs): LDRs, also known as photoresistors, are resistors whose resistance changes with varying light levels. Their resistance decreases as the incident light intensity increases. LDRs are used in light-sensitive applications, such as automatic lighting controls and light meters.

5.     Varistors (Voltage Dependent Resistors - VDRs): Varistors are nonlinear resistors that exhibit a highly nonlinear voltage-current characteristic. They are used for transient voltage suppression and overvoltage protection in circuits. Varistors are designed to handle short-duration voltage spikes by effectively reducing their resistance during such events.

6.     Precision Resistors: Precision resistors are specialized resistors with extremely tight tolerance values, meaning their resistance value is very close to the specified nominal value. They are used in applications where high precision and stability are critical, such as in precision instrumentation.

7.     Surface-Mount Resistors (SMD Resistors): Surface-mount resistors are designed for surface mount technology (SMT) applications. They are compact, come in various sizes, and are soldered directly to the surface of printed circuit boards (PCBs). Surface-mount resistors are commonly used in modern electronics due to their small size and ease of automated assembly.

8.     Chip Resistors: Chip resistors are a subset of surface-mount resistors. They are typically rectangular in shape and come in standardized package sizes. They are widely used in SMT applications for their ease of handling and placement.

9.     Wirewound Resistors: Wirewound resistors consist of a resistive wire wound around a ceramic or metallic core. They are known for their high power-handling capability and accuracy. Wirewound resistors are used in applications where precise resistance values and high power dissipation are required.

10.  Fusible Resistors: Fusible resistors are designed to act as fuses in circuits. In the event of excessive current flow, they intentionally burn out, breaking the circuit to protect other components. They are commonly used in overcurrent protection applications.

The choice of resistor type depends on the specific requirements of the circuit and the application, including factors such as resistance value, power rating, tolerance, temperature stability, and physical size.