Resistance symbol - the resistance symbol is so capricious

Resistance is a fundamental component in electronic circuits, and its symbol plays a crucial role in circuit diagrams. Understanding the different types of resistors and their corresponding symbols is essential for both beginners and professionals in electronics. In this article, we will explore various resistor types, their symbols, and how they are represented in technical drawings.

What is Resistance?

Resistance is denoted by the symbol "R" and measured in ohms (Ω). It refers to the ability of a conductor to oppose the flow of electric current. This property is inherent to the material and does not disappear when the current stops. Even without current, the resistance still exists within the conductor.

Fixed Resistor Symbols

Fixed resistors have a constant resistance value and are represented by the symbol "R". There are two common graphical representations: one used widely in engineering and another that follows international standards. These symbols help identify fixed resistors on circuit diagrams quickly.

Trimmer Resistor Symbols

Trimmer resistors, also known as semi-adjustable resistors, allow for small adjustments in resistance. They are often used in circuits where fine-tuning is required. The symbol for these resistors is also "R", similar to fixed resistors.

Potentiometer Symbols

A potentiometer is an adjustable resistor with the symbol "RP". It can be used as a three-terminal or two-terminal device. Its graphical representation includes an arrow indicating adjustability.

Thermistor Symbols

Thermistors are temperature-sensitive resistors, and their symbol is "RT". Depending on whether the resistance increases or decreases with temperature, they are classified as NTC (Negative Temperature Coefficient) or PTC (Positive Temperature Coefficient).

Photoresistor Symbols

Photoresistors, or light-dependent resistors (LDRs), change resistance based on light intensity. Their symbol is "RL", with diagonal lines representing the light sensitivity.

Varistor Symbols

Varistors are voltage-dependent resistors, and their symbol is "RV". They are used to protect circuits from voltage surges.

Humidity Sensitive Resistor Symbols

Humidity-sensitive resistors change resistance based on environmental humidity. Their symbol is "RS".

Resistor Labeling Methods

Various manufacturers use different labeling systems for resistors. For example, Japanese companies like Sony, Sanyo, and Toshiba have their own unique methods for identifying resistor types and values.

Writing Rules for Fixed Resistor Symbols

Resistors are often labeled using a combination of letters to indicate their type and characteristics. For example, "RJ" stands for metal film resistors, "RT" for carbon film, and "RX" for wirewound. The first letter usually indicates the component type, the second the material, and the third the performance or size.

This article has covered the basics of resistor symbols, their applications, and how they are represented in technical documentation. Whether you're a student, engineer, or hobbyist, understanding these symbols is key to working with electronic circuits effectively.