Electronic color code (B.B. Roy of Great Britain Has a Very Good Wife) Availablestudy.blogspot.in

The electronic color code is used to indicate the values or ratings of electronic components, very commonly for resistors, but also for capacitors, inductors, and others. A separate code, the 25-pair color code, is used to identify wires in some telecommunications cables.

The electronic color code was developed in the early 1920s by the Radio Manufacturers Association (now part of Electronic Industries Alliance^[1] (EIA)), and was published as EIA-RS-279. The current international standard is IEC 60062.^[2]

Colorbands were commonly used (especially on resistors) because they were easily printed on tiny components, decreasing construction costs. However, there were drawbacks, especially forcolor blind people. Overheating of a component, or dirt accumulation, may make it impossible to distinguish brown from red from orange. Advances in printing technology have made printed numbers practical for small components, which are often found in modern electronics.

To distinguish left from right there is a gap between the C and D bands.

band A is first significant figure of component value (left side)
band B is the second significant figure (Some precision resistors have a third significant figure, and thus five bands.)
band C is the decimal multiplier
band D if present, indicates tolerance of value in percent (no band means 20%)

For example, a resistor with bands of yellow, violet, red, and gold will have first digit 4 (yellow in table below), second digit 7 (violet), followed by 2 (red) zeros: 4,700 ohms. Gold signifies that the tolerance is ±5%, so the real resistance could lie anywhere between 4,465 and 4,935 ohms.

Resistors manufactured for military use may also include a fifth band which indicates component failure rate (reliability); refer to MIL-HDBK-199 for further details.

Tight tolerance resistors may have three bands for significant figures rather than two, or an additional band indicating temperature coefficient, in units of ppm/K.

All coded components will have at least two value bands and a multiplier; other bands are optional.

The standard color code per EN 60062:2005 is as follows:

Resistors use preferred numbers for their specific values, which are determined by their tolerance. These values repeat for every decade of magnitude: 6.8, 68, 680, and so forth. In the E24 series the values are related by the 24th root of 10, while E12 series are related by the 12th root of 10, and E6 series by the 6th root of 10. The tolerance of device values is arranged so that every value corresponds to a preferred number, within the required tolerance.

Zero ohm resistors are made as lengths of wire wrapped in a resistor-shaped body which can be substituted for another resistor value in automatic insertion equipment. They are marked with a single black band.^[4]

The 'body-end-dot' or 'body-tip-spot' system was used for radial-lead (and other cylindrical) composition resistors sometimes still found in very old equipment; the first band was given by the body color, the second band by the color of the end of the resistor, and the multiplier by a dot or band around the middle of the resistor. The other end of the resistor was colored gold or silver to give the tolerance, otherwise it was 20%.^[5]

Diode part number[edit]

The part number for diodes was sometimes also encoded as colored rings around the diode, using the same numerals as for other parts. The JEDEC "1N" prefix was assumed, and the balance of the part number was given by three or four rings.

Mnemonics[edit]

Further information: List of electronic color code mnemonics

A useful mnemonic matches the first letter of the color code, by order of increasing magnitude. Here is one that includes tolerance codes gold, silver, and none:

Bad beer rots our young guts but vodka goes well – get some now.^[7]

The colors are sorted in the order of the visible light spectrum: red (2), orange (3), yellow (4), green (5), blue (6), violet (7). Black (0) has no energy, brown (1) has a little more, white (9) has everything and grey (8) is like white, but less intense.^[8]

Examples[edit]

Color-coded resistors

From top to bottom:

Green-Blue-Black-Brown
- 560 ohms ± 1%
Red-Red-Orange-Gold
- 22,000 ohms ± 5%
Yellow-Violet-Brown-Gold
- 470 ohms ± 5%
Blue-Gray-Black-Gold
- 68 ohms ± 5%
violet-red-orange-no band
- 72,000 ohms ± 20%

The physical size of a resistor is indicative of the power it can dissipate, not of its resistance.

Functions _(c++ programming language)

Now that you should have learned about variables, loops, and conditional statements it is time to learn about functions. You should have an idea of their uses as we have already used them and defined one in the guise of main. cin.get() is an example of a function. In general, functions are blocks of code that perform a number of pre-defined commands to accomplish something productive. Functions that a programmer writes will generally require a prototype. Just like a blueprint, the prototype tells the compiler what the function will return, what the function will be called, as well as what arguments the function can be passed. When I say that the function returns a value, I mean that the function can be used in the same manner as a variable would be. For example, a variable can be set equal to a function that returns a value between zero and four. For example: #include <cstdlib> // Include rand() using namespace std; // Make rand() visible int a = rand(); ...

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