This package include with 1/4 Watt 5% Resistor 0.25W Resistor 1 Pack of 15 Value's 10 Resistor of each value. Number of list given 10R,47R,100R,220R,330R,470R,1K,2.2K,4.7K,6.8K,10K,22K,47K,100K,220K
Take a Stance, The Resist Stance
Resistors – the most ubiquitous of electronic components. They are a critical piece in just about every circuit. And they play a major role in our favorite equation, Ohm’s Law.
In this, our pièce de résistance, we’ll cover:
- What is a resistor?!
- Resistor units
- Resistor circuit symbol(s)
- Resistors in series and parallel
- Different variations of resistors
- Color coding decoding
- Surface mount resistor decoding
- Example resistor applications
Some of the concepts in this tutorial build on previous electronics knowledge. Before jumping into this tutorial, consider reading (at least skimming) these first:
- What is Electricity?
- Voltage, Current, Resistance, and Ohm’s Law
- What is a Circuit
- Series vs. Parallel Circuits
- How to Use A Multimeter – Specifically check out the measuring resistance section.
- Metric Prefixes
Resistors are electronic components which have a specific, never-changing electrical resistance. The resistor’s resistance limits the flow of electrons through a circuit.
They are passive components, meaning they only consume power (and can’t generate it). Resistors are usually added to circuits where they complement active components like op-amps, microcontrollers, and other integrated circuits. Commonly resistors are used to limit current, divide voltages, and pull-up I/O lines.
The electrical resistance of a resistor is measured in ohms. The symbol for an ohm is the greek capital-omega: Ω. The (somewhat roundabout) definition of 1Ω is the resistance between two points where 1 volt (1V) of applied potential energy will push 1 ampere (1A) of current.
As SI units go, larger or smaller values of ohms can be matched with a prefix like kilo-, mega-, or giga-, to make large values easier to read. It’s very common to see resistors in the kilohm (kΩ) and megaohm (MΩ) range (much less common to see miliohm (mΩ) resistors). For example, a 4,700Ω resistor is equivalent to a 4.7kΩ resistor, and a 5,600,000Ω resistor can be written as 5,600kΩ or (more commonly as) 5.6MΩ.
All resistors have two terminals, one connection on each end of the resistor. When modeled on a schematic, a resistor will show up as one of these two symbols:
Two common resistor schematic symbols. R1 is an American-style 1kΩ resistor, and R2 is an international-style 47kΩ resistor.
The terminals of the resistor are each of the lines extending from the squiggle (or rectangle). Those are what connect to the rest of the circuit.
The resistor circuit symbols are usually enhanced with both a resistance value and a name. The value, displayed in ohms, is obviously critical for both evaluating and actually constructing the circuit. The name of the resistor is usually an R preceding a number. Each resistor in a circuit should have a unique name/number. For example, here’s a few resistors in action on a 555 timer circuit:
In this circuit, resistors play a key role in setting the frequency of the 555 timer’s output. Another resistor (R3) limits the current through an LED.
Types of Resistors
Resistors come in a variety of shapes and sizes. They might be through-hole or surface-mount. They might be a standard, static resistor, a pack of resistors, or a special variable resistor.
Termination and mounting
Resistors will come in one of two termination-types: through-hole or surface-mount. These types of resistors are usually abbreviated as either PTH (plated through-hole) or SMD/SMT (surface-mount technology or device).
Through-hole resistors come with long, pliable leads which can be stuck into a breadboard or hand-soldered into a prototyping board or printed circuit board (PCB). These resistors are usually more useful in breadboarding, prototyping, or in any case where you’d rather not solder tiny, little 0.6mm-long SMD resistors. The long leads usually require trimming, and these resistors are bound to take up much more space than their surface-mount counterparts.
The most common through-hole resistors come in an axial package. The size of an axial resistor is relative to its power rating. A common ½W resistor measures about 9.2mm across, while a smaller ¼W resistor is about 6.3mm long.
A half-watt (½W) resistor (above) sized up to a quarter-watt (¼W).
Surface-mount resistors are usually tiny black rectangles, terminated on either side with even smaller, shiny, silver, conductive edges. These resistors are intended to sit on top of PCBs, where they’re soldered onto mating landing pads. Because these resistors are so small, they’re usually set into place by a robot, and sent through an oven where solder melts and holds them in place.
A tiny 0603 330Ω resistor hovering over shiny George Washington’s nose on top of a U.S. quarter.
SMD resistors come in standardized sizes; usually either 0805 (0.8mm long by 0.5mm wide), 0603, or 0402. They’re great for mass circuit-board-production, or in designs where space is a precious commodity. They take a steady, precise hand to manually solder, though!
Resistors can be constructed out of a variety of materials. Most common, modern resistors are made out of either a carbon, metal, or metal-oxide film. In these resistors, a thin film of conductive (though still resistive) material is wrapped in a helix around and covered by an insulating material. Most of the standard, no-frills, through-hole resistors will come in a carbon-film or metal-film composition.
Peek inside the guts of a few carbon-film resistors. Resistance values from top to bottom: 27Ω, 330Ω and a 3.3MΩ. Inside the resistor, a carbon film is wrapped around an insulator. More wraps means a higher resistance. Pretty neat!
Other through-hole resistors might be wirewound or made of super-thin metallic foil. These resistors are usually more expensive, higher-end components specifically chosen for their unique characteristics like a higher power-rating, or maximum temperature range.
Surface-mount resistors are usually either thick or thin-film variety. Thick-film is usually cheaper but less precise than thin. In both resistor types, a small film of resistive metal alloy is sandwiched between a ceramic base and glass/epoxy coating, and then connected to the terminating conductive edges.
Special resistor packages
There are a variety of other, special-purpose resistors out there. Resistors may come in pre-wired packs of five-or-so resistor arrays. Resistors in these arrays may share a common pin, or be set up as voltage dividers.
An array of five 330Ω resistors, all tied together at one end.
Resistors don’t have to be static either. Variable resistors, known as rheostats, are resistors which can be adjusted between a specific range of values. Similar to the rheostat is the potentiometer. Pots connect two resistors internally, in series, and adjust a center tap between them creating an adjustable voltage divider. These variable resistors are often used for inputs, like volume knobs, which need to be adjustable.
A smattering of potentiometers. From top-left, clockwise: a standard 10k trimpot, 2-axis joystick, softpot, slide pot, classic right-angle, and a breadboard friendly 10k trimpot.
Decoding Resistor Markings
Though they may not display their value outright, most resistors are marked to show what their resistance is. PTH resistors use a color-coding system (which really adds some flair to circuits), and SMD resistors have their own value-marking system.
Decoding the color bands
Through-hole, axial resistors usually use the color-band system to display their value. Most of these resistors will have four bands of color circling the resistor.
The first two bands indicate the two most-significant digits of the resistor’s value. The third band is a weight value, which multiplies the two significant digits by a power of ten.
The final band indicates the tolerance of the resistor. The tolerance explains how much more or less the actualresistance of the resistor can be compared to what its nominal value is. No resistor is made to perfection, and different manufacturing processes will result in better or worse tolerances. For example, a 1kΩ resistor with 5% tolerance could actually be anywhere between 0.95kΩ and 1.05kΩ.
How do you tell which band is first and last? The last, tolerance band is often clearly separated from the value bands, and usually it’ll either be silver or gold.
Here’s a table of each of the colors and which value, multiplier or tolerance they represent:Color Digit value Multiplier Multiplied Out Tolerance Black 0 100 1 Brown 1 101 10 Red 2 102 100 Orange 3 103 1,000 Yellow 4 104 10000 Green 5 105 100,000 Blue 6 106 1,000,000 Violet 7 107 10,000,000 Gray 8 108 100,000,000 White 9 109 1,000,000,000 Gold ±5% Silver ±10%
Here’s an example of a 4.7kΩ resistor with four color bands:
When decoding the resistor color bands, consult a resistor color code table like the one above. For the first two bands, find that color’s corresponding digit value. The 4.7kΩ resistor has color bands of yellow and violet to begin – which have digit values of 4 and 7 (47). The third band of the 4.7kΩ is red, which indicates that the 47 should be multiplied by 102 (or 100). 47 times 100 is 4,700!
If you’re trying to commit the color band code to memory, a mnemonic device might help. There are a handful of(sometimes unsavory) mnemonics out there, to help remember the resistor color code. A good one, which spells out the difference between black and brown is:
“Big brown rabbits often yield great big vocal groans when gingerly snapped.”
Or, if you remember “ROY G. BIV”, subtract the indigo (poor indigo, no one remembers indigo), and add black and brown to the front and gray and white to the back of the classic rainbow color-order.
Color Code Calculator
If you’d rather skip the math (we won’t judge :), and just use a handy calculator, give this a try!Band 1 Band 2 Band 3 Band 4 Value 1 (MSV) Value 2 Weight Tolerance Black (0) Brown (1) Red (2) Orange (3) Yellow (4) Green (5) Blue (6) Violet (7) Gray (8) White (9) Black (0) Brown (1) Red (2) Orange (3) Yellow (4) Green (5) Blue (6) Violet (7) Gray (8) White (9) Black (1) Brown (10) Red (100) Orange (1k) Yellow (10k) Green (100k) Blue (1M) Violet (10M) Gray (100M) White (1G) Gold (± 5%) Silver (± 10%) Resistance: 1,000 Ω ±5%
Decoding surface-mount markings
SMD resistors, like those in 0603 or 0805 packages, have their own way of displaying their value. There are a few common marking methods you’ll see on these resistors. They’ll usually have three to four characters – numbers or letters – printed on top of the case.
If the three characters you’re seeing are all numbers, you’re probably looking at an E24 marked resistor. These markings actually share some similarity with the color-band system used on the PTH resistors. The first two numbers represent the first two most-significant digits of the value, the last number represents a magnitude.
In the above example picture, resistors are marked 104, 105, 205, 751, and 754. The resistor marked with 104 should be 100kΩ (10×104), 105 would be 1MΩ (10×105), and 205 is 2MΩ (20×105). 751 is 750Ω (75×101), and 754 is 750kΩ (75×104).
Another common coding system is E96, and it’s the most cryptic of the bunch. E96 resistors will be marked with three characters – two numbers at the beginning and a letter at the end. The two numbers tell you the first three digits of the value, by corresponding to one of the not-so-obvious values on this lookup table.Code Value Code Value Code Value Code Value Code Value Code Value 01 100 17 147 33 215 49 316 65 464 81 681 02 102 18 150 34 221 50 324 66 475 82 698 03 105 19 154 35 226 51 332 67 487 83 715 04 107 20 158 36 232 52 340 68 499 84 732 05 110 21 162 37 237 53 348 69 511 85 750 06 113 22 165 38 243 54 357 70 523 86 768 07 115 23 169 39 249 55 365 71 536 87 787 08 118 24 174 40 255 56 374 72 549 88 806 09 121 25 178 41 261 57 383 73 562 89 825 10 124 26 182 42 267 58 392 74 576 90 845 11 127 27 187 43 274 59 402 75 590 91 866 12 130 28 191 44 280 60 412 76 604 92 887 13 133 29 196 45 287 61 422 77 619 93 909 14 137 30 200 46 294 62 432 78 634 94 931 15 140 31 205 47 301 63 442 79 649 95 953 16 143 32 210 48 309 64 453 80 665 96 976
The letter at the end represents a multiplier, matching up to something on this table:Letter Multiplier Letter Multiplier Letter Multiplier Z 0.001 A 1 D 1000 Y or R 0.01 B or H 10 E 10000 X or S 0.1 C 100 F 100000
So a 01C resistor is our good friend, 10kΩ (100×100), 01B is 1kΩ (100×10), and 01D is 100kΩ. Those are easy, other codes may not be. 85A from the picture above is 750Ω (750×1) and 30C is actually 20kΩ.
The power rating of a resistor is one of the more hidden values. Nevertheless it can be important, and it’s a topic that’ll come up when selecting a resistor type.
Power is the rate at which energy is transformed into something else. It’s calculated by multiplying the voltage difference across two points by the current running between them, and is measured in units of a watt (W). Light bulbs, for example, power electricity into light. But a resistor can only turn electrical energy running through it into heat. Heat isn’t usually a nice playmate with electronics; too much heat leads to smoke, sparks, and fire!
Every resistor has a specific maximum power rating. In order to keep the resistor from heating up too much, it’s important to make sure the power across a resistor is kept under it’s maximum rating. The power rating of a resistor is measured in watts, and it’s usually somewhere between ⅛W (0.125W) and 1W. Resistors with power ratings of more than 1W are usually referred to as power resistors, and are used specifically for their power dissipating abilities.
Finding a resistor’s power rating
A resistor’s power rating can usually be deduced by observing its package size. Standard through-hole resistors usually come with ¼W or ½W ratings. More special purpose, power resistors might actually list their power rating on the resistor.
These power resistors can handle a lot more power before they blow. From top-right to bottom-left there are examples of 25W, 5W and 3W resistors, with values of 2Ω, 3Ω 0.1Ω and 22kΩ. Smaller power-resistors are often used to sense current.
The power ratings of surface mount resistors can usually be judged by their size as well. Both 0402 and 0603-size resistors are usually rated for 1/16W, and 0805’s can take 1/10W.
Measuring power across a resistor
Power is usually calculated by multiplying voltage and current (P = IV). But, by applying Ohm’s law, we can also use the resistance value in calculating power. If we know the current running through a resistor, we can calculate the power as:
Or, if we know the voltage across a resistor, the power can be calculated as:
Pack of 15 number of Resistors: 1 x 1/4 Watt 5% Resistor 0.25W Resistor 1 Pack of 15 Value's 10 Resistor of each value.Resistance Value Pieces Resistance: 10R 10 Resistance: 47R 10 Resistance: 100R 10 Resistance: 220R 10 Resistance: 330R 10 Resistance: 470R 10 Resistance: 1K 10 Resistance: 2.2K 10 Resistance: 4.7K 10 Resistance: 6.8K 10 Resistance: 10K 10 Resistance: 22K 10 Resistance: 47K 10 Resistance: 100K 10 Resistance: 220K 10