Course Content
S-1 General Safety Rules S-2 Effects of Electric Current S-3 On The Job S-4 Protective Clothing S-5 Ladders & Scaffolds S-6 Fires S-7 Ground Fault Circuit Interrupters S-8 Grounding
Unit 1 – Atomic Structure
Objectives After studying this unit, you should be able to: List the principal parts of an atom State the law of charges Discuss the centripetal force  Discuses the differences between conductors & insulators Preview Electricity is the driving force that provides most of the power for the industrialized world. It is used to light houses, cook meals, heat and cool building, run electric motors, & supplies ignition for most automobiles in the world, 
Electrical Theory Fundamentals
About Lesson

Resistors are passive electronic components used to control the flow of electric current in circuits. In this lesson, we will explore various types of resistors, their construction, characteristics, and applications. Let’s begin!

I. Carbon Composition Resistors:

A. Construction:

Carbon Resistor
  1. Made of a cylindrical ceramic or phenolic core.
  2. A resistive element made of carbon powder mixed with a binder material.
  3. End caps with wire leads for connection.

B. Characteristics:

  1. Low cost and widely available.
  2. Tolerance typically ranges from 5% to 20%.
  3. Power ratings usually up to 1/2 or 1 watt.
  4. Sensitive to temperature and environmental conditions.
  5. Suitable for general-purpose applications where precision is not critical.

C. Applications:

  1. Voltage dividers.
  2. Current limiting.
  3. General circuit protection.

II. Metal Film Resistors:

A. Construction:

Metal Film Resistor
  1. A thin metal film (usually nickel-chromium or tantalum) is deposited on a ceramic substrate.
  2. End caps with wire leads or surface mount contacts for connection.

B. Characteristics:

  1. High precision and stability.
  2. Tolerance typically ranges from 1% to 5%.
  3. Power ratings usually up to 1/4 or 1/2 watt.
  4. Better temperature coefficient compared to carbon composition resistors.
  5. Suitable for applications requiring accuracy and stability.

C. Applications:

  1. Precision measuring instruments.
  2. Analog and digital circuits.
  3. Audio equipment.

III. Wire-Wound Resistors:

A. Construction:

Wire Wound Resistor
  1. A resistive wire (usually made of nichrome or constantan) is wound around a ceramic or fiberglass core.
  2. End caps with wire leads or surface mount contacts for connection.
  3. Sometimes coated with an insulating layer for protection.

B. Characteristics:

  1. High power handling capability.
  2. Tolerance typically ranges from 1% to 10%.
  3. Power ratings can range from a few watts to several hundred watts.
  4. Higher inductance due to the wire winding.
  5. Used in high-power applications where precision and stability are required.

C. Applications:

  1. Power supplies and converters.
  2. Motor control circuits.
  3. Industrial equipment.

IV. Film Resistors:

Film Resistor

A. Metal Oxide Film Resistors:

  1. Made by depositing a metal oxide film on a ceramic substrate.
  2. Excellent stability, accuracy, and low noise characteristics.
  3. Widely used in electronic devices and equipment.

B. Thick Film Resistors:

  1. Made by screen-printing a resistive paste on a ceramic substrate.
  2. Cost-effective and commonly used in consumer electronics.
  3. Tolerance ranges from 1% to 5%.

C. Thin Film Resistors:

  1. Made by depositing a thin resistive film on a ceramic or glass substrate.
  2. High precision, low noise, and stable over a wide temperature range.
  3. Suitable for applications requiring high accuracy and stability.

V. Other Types of Resistors:

A. Variable Resistors (Potentiometers and Rheostats):

Variable Resistor
  1. Potentiometers: Three-terminal devices used for voltage division and adjustment.
  2. Rheostats: Two-terminal devices used to control current by adjusting resistance.

    B. Network Resistors:

    1. Resistor Arrays: Multiple resistors integrated into a single package, used for compact circuit design and precise matching.
    2. Resistor Networks: Arrays of resistors connected in specific configurations, such as series, parallel, or ladder networks.

    C. Specialized Resistors:

    1. High-Voltage Resistors: Designed to withstand high voltage levels without breakdown.
    2. High-Frequency Resistors: Optimized for use in radio frequency (RF) and microwave circuits.
    3. Fusible Resistors: Designed to act as fuses, protecting circuits from excessive current.
    4. Thermistors: Resistors whose resistance varies with temperature, used for temperature sensing and compensation.
    5. Varistors: Voltage-dependent resistors used for transient voltage suppression and surge protection.

    Conclusion: In conclusion, resistors come in various types, each with its own construction, characteristics, and applications. From carbon composition resistors to metal film, wire-wound, and specialized resistors, understanding the different types allows engineers and designers to select the appropriate resistor for specific circuit requirements. As you continue your journey in electronics, remember to consider the desired tolerance, power rating, stability, and precision when choosing resistors for your circuits.

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