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
Carbon composition resistorResistors
What it does
Uses a resistive bulk mixture rather than a deposited film. Found in many historical receivers and some specialized applications.
Example
An older radio bias network.
Important distinction
Age, noise and stability must be assessed; appearance is not a measurement.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Carbon film resistorResistors
What it does
Uses a carbon film as the resistive element. It is a fixed-resistor construction rather than a separate circuit function.
Example
A general-purpose bias resistor.
Important distinction
Select by the required specifications rather than color or size alone.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Current-sense resistorResistors
What it does
Produces a small voltage drop related to current, allowing a circuit to estimate or regulate that current.
Example
An amplifier or converter current-monitoring path.
Important distinction
Connection resistance and thermal behavior can affect accuracy.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Fixed resistorResistors
What it does
Opposes current flow and dissipates electrical energy as heat. Resistance is measured in ohms; a circuit also depends on tolerance and operating conditions.
Example
Limiting current in a low-voltage indicator circuit.
Important distinction
A resistance value alone does not specify power, voltage or pulse suitability.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Fusible resistorResistors
What it does
Provides resistance with a specified protective opening behavior under applicable conditions.
Example
A documented protective input network.
Important distinction
An ordinary resistor is not an equivalent protective replacement.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Metal-foil resistorResistors
What it does
A precision resistor construction selected for particular stability and accuracy requirements.
Example
A measurement reference network.
Important distinction
The required environment and mounting conditions still matter.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Metal film resistorResistors
What it does
Uses a metal resistive film. Available with characteristics suited to many precision and low-noise applications.
Example
A measurement divider.
Important distinction
Its actual tolerance and temperature coefficient come from the specific part.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Potentiometer and rheostatResistors
What it does
A potentiometer provides an adjustable tap on a resistance element. A rheostat connection uses variable resistance in a current path.
Example
A volume control or adjustable test load.
Important distinction
Taper, power rating and terminal arrangement are not interchangeable.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Thick-film and thin-film resistorResistors
What it does
Distinct film constructions with different available precision, stability and application characteristics.
Example
A board-level signal network.
Important distinction
Use the exact series specifications; construction is not a complete rating.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Trimmer and resistor networkResistors
What it does
A trimmer supports occasional adjustment; a network combines several resistors in one package.
Example
Calibration or multiple digital-input pull-ups.
Important distinction
Check internal connections; some networks share a common terminal.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Wirewound resistorResistors
What it does
Uses resistance wire wound on a supporting form. Construction can introduce inductance as well as resistance.
Example
A power load or historical supply resistor.
Important distinction
A part suited to DC may not suit a high-frequency circuit.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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.
Zero-ohm linkResistors
What it does
A component used as a defined connection rather than a precision resistance.
Example
Routing a board connection.
Important distinction
Current and thermal limits still apply.
Specifications to read
Resistance (Ω), tolerance (%), power (W), working voltage, temperature coefficient and pulse behavior.
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