Encyclopedia of Electronic Components Volume 1

1. Batteries: Electrochemical Power Sources Explained

A battery contains one or more electrochemical cells in which chemical reactions create an electrical potential between two immersed terminals.

Electrochemical reactions. Batteries convert chemical energy into electrical energy through redox reactions. These reactions occur between the electrodes (anode and cathode) and the electrolyte, creating a potential difference that drives current through an external circuit.

Disposable vs. Rechargeable. Batteries are categorized as disposable (primary) or rechargeable (secondary). Disposable batteries, like alkaline, offer high energy density and long shelf life but cannot be reliably recharged. Rechargeable batteries, such as lithium-ion, can be recharged multiple times but have lower energy density and higher self-discharge rates.

Understanding Battery Values. Key battery specifications include voltage, amperage, and capacity (measured in amp-hours). Voltage determines the electrical potential, amperage indicates the current delivery capability, and capacity reflects the total charge the battery can store. These values are crucial for matching a battery to a specific application.

2. Jumpers: Low-Cost Connection Alternatives

A jumper is a low-cost substitute for a switch, where a connection has to be made (or unmade) only a few times during the lifetime of a product.

Simple Circuit Configuration. Jumpers are simple connectors used to close or open circuits on a semi-permanent basis. They consist of a plastic housing with internal metal contacts that bridge two or more pins on a circuit board, offering a basic and inexpensive way to configure settings.

Jumper Variants. Jumpers come in various forms, including those with different pin spacings (0.1" or 2mm) and multiple sockets. Some have finger grips for easier handling. They are typically used with headers, which are arrays of pins soldered onto a circuit board.

Practical Considerations. While jumpers are cost-effective, they are prone to being dropped, lost, or incorrectly placed. Oxidation can also affect their reliability. They are best suited for settings that require infrequent changes and where the simplicity of the connection outweighs the potential for handling issues.

3. Fuses: Protecting Circuits from Overcurrent

A fuse protects an electrical circuit or device from excessive current when a metal element inside it melts to create an open circuit.

Overcurrent Protection. Fuses are safety devices designed to protect circuits from damage caused by excessive current flow. They contain a metal element that melts and breaks the circuit when the current exceeds a specified level, preventing overheating and potential fires.

Fuse Ratings and Types. Fuses are rated by their current and voltage capacity, as well as their response time (fast-acting, medium-acting, or slow-blowing). Different types of fuses, such as cartridge, automotive, and surface mount, are available for various applications. Resettable fuses (PTCs) offer a reusable alternative.

Proper Fuse Usage. Selecting the correct fuse involves matching its current and voltage ratings to the circuit's requirements. Slow-blowing fuses are suitable for circuits with inrush currents, while fast-acting fuses are ideal for sensitive electronics. Proper placement and avoiding common mistakes, such as using a wire as a substitute, are crucial for effective protection.

4. Pushbuttons: Momentary Connection Control

A pushbutton contains at least two contacts, which close or open when the button is pressed.

Momentary Action. Pushbuttons provide a temporary electrical connection when pressed, returning to their original state upon release. They are used for initiating actions, such as starting a device or triggering a function, and are available in various configurations (normally open, normally closed, etc.).

Pushbutton Variants. Pushbuttons come in many styles, including tactile switches, membrane pads, and emergency switches. They can have different poles and throws (SPST, SPDT, DPST), on-off behaviors (momentary, latching), and mounting options (panel mount, PC mount).

Practical Considerations. When using pushbuttons, consider factors such as mounting, LED integration, and potential problems like contact bounce. Proper labeling and selection of appropriate styles and caps are essential for effective integration into electronic projects.

5. Switches: Maintaining Circuit States

A switch contains at least two contacts, which close or open when an external lever or knob is flipped or moved.

Maintaining Circuit States. Switches are used to establish or break electrical connections, maintaining a specific state (on or off) until manually changed. They are essential components for controlling power, selecting modes, and configuring settings in electronic devices.

Switch Types and Terminology. Switches come in various forms, including toggle, rocker, slider, and rotary. Key specifications include poles and throws (SPST, SPDT, DPST), on-off behavior (momentary, latching), and contact plating options.

Practical Considerations. When using switches, consider factors such as arcing, contact contamination, and mechanical wear. Proper mounting, selecting the correct terminal type, and understanding schematic symbols are crucial for effective integration into electronic circuits.

6. Rotary Switches: Selecting from Multiple Circuits

A rotary switch makes an electrical connection between a rotor, mounted on a shaft that is turned by a knob, and one of two or more stationary contacts.

Multi-Position Selection. Rotary switches allow selection from multiple circuits or settings by rotating a knob or dial. They are used in applications requiring selection from a limited number of options, such as band selection in radios or input selection in audio amplifiers.

Rotary Switch Variants. Rotary switches come in various forms, including conventional, rotary DIP, and Gray code. They can have multiple poles and throws, and may include features like detents, keylocks, and mechanical encoders.

Practical Considerations. When using rotary switches, consider factors such as contact vulnerability, contact overload, and misalignment. Proper selection of shaft, knobs, and mounting hardware is essential for effective integration into electronic projects.

7. Rotational Encoders: Converting Rotation to Digital Signals

A rotational encoder has a knob that a user can turn to display a series of prompts on an LCD screen, or to adjust the input or output on a product such as a stereo receiver.

Digital Rotation Sensing. Rotational encoders convert mechanical rotation into digital signals, providing a means for precise control and feedback in electronic systems. They are used in applications such as volume control, menu navigation, and position sensing.

Encoder Types and Operation. Rotational encoders generate pulses as the shaft rotates, with the number of pulses per rotation (PPR) determining the resolution. They can be incremental (relative) or absolute, and may include detents for tactile feedback.

Practical Considerations. When using rotational encoders, consider factors such as contact bounce, sliding noise, and the need for debouncing circuits. Proper selection of shaft, knobs, and mounting hardware is essential for effective integration into electronic projects.

8. Relays: Electromechanical Remote Control

A relay enables a signal or pulse of electricity to switch on (or switch off) a separate flow of electricity.

Remote Circuit Control. Relays use a small electrical signal to control a separate, often higher-power, circuit. They provide electrical isolation between the control circuit and the load, making them suitable for applications requiring remote switching or high-voltage control.

Relay Types and Operation. Relays come in various forms, including electromechanical, solid-state, and reed relays. Key specifications include coil voltage, contact rating, and on-off behavior (latching, nonlatching).

Practical Considerations. When using relays, consider factors such as coil voltage, contact rating, and pinout variations. Proper wiring, protection against voltage spikes, and understanding schematic symbols are crucial for effective integration into electronic circuits.

9. Resistors: Controlling Current Flow

A resistor is one of the most fundamental components in electronics. Its purpose is to impede a flow of current and impose a voltage reduction.

Current and Voltage Control. Resistors limit current flow and create voltage drops in electronic circuits. They are essential components for setting bias points, limiting current to LEDs, and creating voltage dividers.

Resistor Types and Values. Resistors come in various forms, including carbon film, metal film, and wire-wound. Key specifications include resistance value (measured in ohms), tolerance, and power rating.

Practical Considerations. When using resistors, consider factors such as heat dissipation, noise, and inductance. Understanding resistor color codes, selecting appropriate values, and avoiding common mistakes are crucial for effective integration into electronic circuits.

10. Potentiometers: Adjustable Resistance and Voltage Division

A potentiometer contains at least two contacts, which close or open when an external lever or knob is flipped or moved.

Variable Resistance and Voltage. Potentiometers provide adjustable resistance and voltage division in electronic circuits. They are used for controlling volume, adjusting brightness, and setting parameters in various applications.

Potentiometer Types and Operation. Potentiometers come in various forms, including rotary, slider, and trimmer. Key specifications include resistance value, taper (linear, log), and power rating.

Practical Considerations. When using potentiometers, consider factors such as wear and tear, knob compatibility, and shaft length. Proper selection of taper, mounting hardware, and avoiding common mistakes are crucial for effective integration into electronic circuits.

11. Capacitors: Storing and Releasing Electrical Energy

A capacitor contains at least two contacts, which close or open when an external lever or knob is flipped or moved.

Energy Storage and Filtering. Capacitors store electrical energy and block DC current while passing AC signals. They are used for smoothing power supplies, filtering noise, and timing circuits.

Capacitor Types and Values. Capacitors come in various forms, including electrolytic, ceramic, and film. Key specifications include capacitance value (measured in farads), voltage rating, and dielectric type.

Practical Considerations. When using capacitors, consider factors such as polarity, voltage overload, and leakage. Proper selection of dielectric, understanding capacitor codes, and avoiding common mistakes are crucial for effective integration into electronic circuits.

12. Inductors: Harnessing Electromagnetic Induction

Inductors are formed from a variety of materials.

Electromagnetic Energy Storage. Inductors store energy in a magnetic field when current flows through them. They are used for filtering, energy storage, and impedance matching in electronic circuits.

Inductor Types and Values. Inductors come in various forms, including air-core, ferrite-core, and toroidal. Key specifications include inductance value (measured in henries), current rating, and Q factor.

Practical Considerations. When using inductors, consider factors such as saturation, RF problems, and core material. Proper selection of core type, understanding inductor codes, and avoiding common mistakes are crucial for effective integration into electronic circuits.

Last updated: February 24, 2025