Electronic Components & Circuits
A broad reference to parts, instruments and circuit functions, explained in everyday language with labeled illustrations, examples and specification checks.
How to use this list
Open an entry to see its illustration, what it does, an example and the specifications that matter. Tap any image to enlarge it. Images are original representative illustrations, not photographs, exact pinouts or guarantees of physical identification. Component families and circuit arrangements are distinct: a capacitor is a part; a filter is a circuit that may use several parts. This reference covers common and important families, rather than every manufacturer part number or specialized circuit ever made.
Examples explain function; they are not universal replacement or wiring instructions. Appearance, package size and a matching nominal value do not establish compatibility. Stored charge, mains, vehicle batteries and high-voltage equipment require appropriate precautions and qualified procedures.
Search the free reference
12 of 160 entries shown. Search matches all entered words across names and explanations.
Browse by category
Accelerometer and gyroscopeSensors and Transducers
What it does
Measure acceleration-related and angular-rate-related quantities through their specified sensing systems.
Example
Motion monitoring.
Important distinction
Axes, range, calibration and interface must be interpreted correctly.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Encoder and potentiometric sensorSensors and Transducers
What it does
An encoder represents movement through encoded outputs; a potentiometric sensor represents position through a resistive relationship.
Example
A control knob or position measurement.
Important distinction
Incremental, absolute and analog interfaces should not be confused.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Hall-effect sensorSensors and Transducers
What it does
Measures or detects magnetic influence through a semiconductor sensing principle.
Example
Position, speed or current sensing.
Important distinction
Analog, switching and digital-output versions require different interfaces.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Humidity sensorSensors and Transducers
What it does
Produces an electrical response related to moisture in its specified environment.
Example
Environmental measurement.
Important distinction
Temperature, contamination and calibration can influence results.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
MicrophoneSensors and Transducers
What it does
Converts sound-related motion or pressure into an electrical signal using an appropriate transducer technology.
Example
A car-radio call input or recording system.
Important distinction
Dynamic, electret and digital microphones are not interchangeable without suitable circuitry.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
NTC thermistorSensors and Transducers
What it does
A temperature-dependent resistor whose resistance generally decreases as temperature rises in its specified range.
Example
Temperature sensing or selected inrush arrangements.
Important distinction
A sensing thermistor and an inrush limiter have different application requirements.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
PhotoresistorSensors and Transducers
What it does
Changes resistance with incident light in its intended operating range.
Example
A light-dependent control.
Important distinction
Response speed, spectral behavior and application restrictions vary.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Piezoelectric elementSensors and Transducers
What it does
Converts mechanical stress and electrical excitation through piezoelectric behavior.
Example
A vibration sensor or buzzer.
Important distinction
Sensor and actuator applications need different drive and input conditions.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Pressure sensorSensors and Transducers
What it does
Converts a pressure-related physical condition into a specified electrical output.
Example
A monitored pneumatic system.
Important distinction
Absolute, gauge and differential types measure different references.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
PTC thermistorSensors and Transducers
What it does
A device whose resistance increases over an applicable temperature region.
Example
Thermal sensing or protection in an appropriate design.
Important distinction
Behavior and switching characteristics depend on the actual technology.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Strain gauge and load cellSensors and Transducers
What it does
A strain-sensitive element and associated assembly convert mechanical deformation into a measurable electrical change.
Example
Weight or force measurement.
Important distinction
Calibration, mounting and signal conditioning affect accuracy.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Thermocouple and RTDSensors and Transducers
What it does
A thermocouple produces a temperature-related voltage; an RTD uses a calibrated resistance-temperature relationship.
Example
Temperature instrumentation.
Important distinction
Both need suitable measurement circuits; they are not equivalent interfaces.
Specifications to read
Measured quantity/reference, range, accuracy, response, supply/bias, interface, calibration and environment.
A rating is a limit or condition, not a guarantee of suitability. Use the manufacturer's data sheet for the exact component and the equipment's schematic for its intended role.
Visual comparison guides
Compare representative physical forms, then read the entries for their different functions. Many parts share package shapes. Appearance alone cannot identify ratings, internal construction or terminal assignments.
Units and worked examples
| Quantity | Unit | Meaning |
|---|---|---|
| Voltage | V, volts | Potential difference between two points. |
| Current | A, amperes | Rate of charge flow. |
| Resistance | Ω, ohms | Resistance to current flow. |
| Power | W, watts | Rate of energy transfer or dissipation. |
| Capacitance | F, farads | Charge change per voltage change. |
| Inductance | H, henries | Relationship between current change and induced voltage. |
| Frequency | Hz, hertz | Cycles per second. |
Prefixes: k = 1,000; M = 1,000,000; m = 0.001; μ = 0.000001; n = 0.000000001; p = 0.000000000001. Case matters: M and m are different.
Resistor example
For an ideal 1 kΩ resistor with 5 V across it: I = V/R = 5/1,000 = 0.005 A = 5 mA. Dissipation is P = V²/R = 25/1,000 = 0.025 W. This arithmetic does not select a real part without its temperature, voltage and application requirements.
Tolerance example
A 1 kΩ resistor with ±5% nominal tolerance spans 950 Ω to 1,050 Ω at the specified conditions. Tolerance is different from drift with temperature or aging.
Capacitance and timing example
10 μF = 10,000 nF. An ideal first-order RC network with R = 1 kΩ and C = 10 μF has τ = RC = 0.01 s = 10 ms. A time constant is not automatically the delay of every timer using those parts.
Stored energy
Ideal capacitor charge is Q = CV; stored energy is E = ½CV². Doubling voltage at the same capacitance quadruples the stored energy. These are learning equations, not a discharge procedure.
Schematic symbols, labels and markings
Reference letters identify components in a drawing; conventions vary by manufacturer and standard. Always read the drawing's legend.
| Common label | Often used for |
|---|---|
| R | Resistor |
| C | Capacitor |
| L | Inductor |
| D | Diode |
| Q | Transistor |
| U / IC | Integrated circuit |
| T | Transformer |
| K / RL | Relay |
| SW / S | Switch |
| J / P / CN | Connector |
| F | Fuse |
| Y / X | Crystal or resonator |
| TP | Test point |
| V / VT | Tube in some historical documentation |
R17 identifies a component location, not a resistance value. A marking such as 4R7 may mean 4.7 Ω in an applicable resistor convention. Three-digit markings such as 104 often represent 100,000 base units: 100 kΩ for a resistor or 100,000 pF = 100 nF for an applicable capacitor code. Confirm the component family and marking system; short codes can be ambiguous.
Common questions
Can I replace a part with any higher-rated one?
No. A higher headline rating does not ensure suitable function, polarity, frequency behavior, package, protective approval or circuit stability.
Does a part that looks normal have to be good?
No. Visual observations can help, but many electrical changes leave no obvious external sign.
Are capacitance, ESR and leakage the same?
No. They describe different properties. A single test cannot establish every capacitor failure mode.
Can I measure every component while it remains connected?
Other paths can affect an in-circuit result. Interpretation depends on the circuit and instrument. Internal work also requires a suitable qualified safety procedure.
Does a matching package establish a transistor or IC replacement?
No. Pinout, function, voltage, drive, timing, heat and application requirements must match.
Is a component the same thing as a circuit?
A component is a building block. A circuit connects building blocks to perform a function. The same component family can serve many circuit roles.
How do I begin learning?
Start with units, schematic labels, resistor/capacitor/inductor functions and signal-versus-power paths. Use disconnected parts or an instructor-approved low-voltage trainer before considering customer equipment.
Is this reference free?
Yes. Every entry, example and reference on this page is public. The separate repair masterclasses have their own free previews and paid lessons.
Manufacturer references
Original plain-language summaries and educational examples. These references support further study; exact product data sheets and equipment manuals remain authoritative for a real application.
Save to Pinterest