Understanding common electronic components in PCBs
December 11, 2025
Basic components and the functions
- Diode: permits electric current to flow in one direction only while blocking reverse current flow.
- Capacitor: A capacitor is a passive electronic component that stores electrical energy in an electric field and releases it when required by the circuit.
- Resistor: A resistor is a passive electronic component that resists, limits, and controls electric current flow, as well as divides voltage in a circuit.
- Transistor: A transistor is a three-terminal semiconductor device that amplifies electrical signals and switches circuits on and off with a small base current controlling larger currents.
- Transformer: A transformer is a static electrical device that transfers alternating current (AC) electrical energy between circuits while adjusting voltage and current levels.
- Inductor: An inductor is a passive electronic component that stores electrical energy in a magnetic field and resists changes in current flow.
- AC: Alternating Current (AC) is an electric current that periodically reverses its direction of flow and changes its magnitude continuously over time.
- DC: Direct Current (DC) is an electric current that flows consistently in a single direction without periodic reversal.
- Variable Resistor: A variable resistor is an adjustable passive component that enables manual modification of resistance to control current and voltage levels in a circuit.
- LED: A light-emitting diode (LED) is a semiconductor component that converts electrical energy directly into visible light or infrared radiation when current flows through it.
- Zener Diode: A Zener diode is a specialized semiconductor component that maintains a constant voltage across its terminals when operating in reverse breakdown mode.
- Open Switch: An open switch is a mechanical or electrical component that breaks the circuit and stops the flow of electric current completely.
- Bridge rectifier: A bridge rectifier is an electronic circuit module that converts alternating current (AC) into direct current (DC) efficiently using four diodes arranged in a bridge configuration.
- Fuse: A fuse is a safety electrical component that melts to break the circuit automatically when current exceeds a safe threshold, protecting other devices from damage.
- Battery: A battery is an electrochemical device that stores chemical energy and converts it into direct electrical current for powering electronic devices.
- Relay Switch: A relay switch is an electrically controlled switch that uses a small input current to activate a larger current circuit for high-power device control.
- Integrated Circuit: An integrated circuit (IC) is a miniaturized electronic chip that integrates thousands to billions of components (e.g., transistors, resistors) to perform complex computing, signal processing, or control functions in a circuit.
- Loudspeaker: A loudspeaker is an electroacoustic transducer that converts electrical audio signals into audible sound waves.
- Microphone: A microphone is an electroacoustic transducer that converts audible sound waves into corresponding electrical audio signals.
- LDR: An LDR (Light Dependent Resistor) is a photosensitive component whose resistance decreases with increasing light intensity and increases in darkness.
- Thermistor: A thermistor is a temperature-sensitive resistor whose resistance changes significantly in response to variations in temperature.
- Photodiod: A photodiode is a light-sensitive semiconductor device that generates an electrical current in response to incident light.
- Seven-Segment: A seven-segment display is an electronic component that shows numerical digits or simple characters by illuminating specific combinations of its seven LED segments.