Resistor component – Learning electronics resistors

Resistors are the most common component in electronics. You will typically see them represented by their schematic symbol in schematic diagrams as either a jagged line or less commonly as a rectangle.

They are used to

  • Limit current:
  • Divide voltage: Primarily covered while studying voltage dividers.
  • Dissipate heat/power: Typically just an unfortunate byproduct of limiting current that must be dissipated to avoid damage.

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Resistor component 1K blue through hole schematics unit symbol diagram by electronzap electronzapdotcom
Resistor component 1K blue through hole schematics unit symbol diagram by electronzap electronzapdotcom

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Basic electrical properties of the resistor are:

I = V/R is the ohms law formula for current (I) through the resistor is based on the voltage (V) across the resistor and it’s resistance (R). Units are in volts for the voltages, Ohms for the resistance and Amps for current.

  • 1V/1Ω = 1A
  • 1V/1000Ω = 0.001A (1mA)

P = VI is the power formula for the heat that is generated and must be dissipated. It is the voltage across a resistor times the current through it. The unit for power is the watt, and the resistor should be rated to handle twice the wattage that it is expected to dissipate with adequate air flow. Most resistor are 1/4 (0.25W).

  • 1V x 1A = 1W
  • 0.001A x 1V = 0.001W

The through hole versions have 2 wire leads (pronounced like “leeds”) coming out of both ends of a semi cylindrical package that has a narrow middle.

  • Omega symbol (Ω) used to indicate ohms.
  • Color bands tell you the rated value plus the tolerance, which is the percent variation the actual value might be from the rated value. You don’t need to learn how to read them, but if you do, then look up how to read resistor color codes.
  • Most resistor values used are in the thousands (kilo) of ohms. a 1,000Ω resistor is usually referred to as being a 1kΩ (one kilohm), or simply as a 1k resistor. 10k is another common value resistor,


Resistor component basic properties explained for DIY learning electronics

More resistor details

  • Resistors are commonly in the thousands of ohms. Kilo stands for thousand and is abbreviated as the letter k when added to a number. A 10kΩ resistor is a 10,000 ohm resistor. Sometimes the Omega symbol is omitted though, so you will often see resistors on schematic symbols with their resistance values simply written like “1K” or “10K”. Occasionally R is used in place of the Ω symbol.

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Related topics:

Other basic electronics topics that you should know before moving on to more advanced topics.

555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.

Other topics:

These pages are still being compiled.

Circuits covered more quickly series:

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