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Measure resistors with our M300 Volt Ohm meter

How to read Resistor Color Codes

First the code

The mnemonic

Bad Boys Ravish Only Young Girls But Violet Gives Willingly PC_fascists

Black is also easy to remember as zero because of the nothingness common to both.

(Please don't add or change the mnemonic - it will only get reverted -admin)

How to read the code

,

First find the tolerance band, it will typically be gold ( 5%) and sometimes silver (10%). Starting from the other end, identify the first band - write down the number associated with that color; in this case Blue is 6. Now 'read' the next color, here it is red so write down a '2' next to the six. (you should have '62' so far.) Now read the third or 'multiplier exponent' band and write down that as the number of zeros. In this example it is two so we get '6200' or '6,200'. If the 'multiplier exponent' band is Black (for zero) don't write any zeros down. If the 'multiplier exponent' band is Gold move the decimal point one to the left. If the 'multiplier exponent' band is Silver move the decimal point two places to the left. If the resistor has one more band past the tolerance band it is a quality band. Read the number as the '% Failure rate per 1000 hour' This is rated assuming full wattage being applied to the resistors. (To get better failure rates, resistors are typically specified to have twice the needed wattage dissipation that the circuit produces). Some resistors use this band for temco information. 1% resistors have three bands to read digits to the left of the multiplier. They have a different temperature coefficient in order to provide the 1% tolerance. At 1% the temperature coefficient starts to become an important factor. at +/-200 ppm a change in temperature of 25 Deg C causes a value change of up to 1%

BS 1852 Coding for resistor values

BS 1852(British Standard 1852). The letter R is used for Ohms and K for Kohms M for Megohms and placed where the decimal point would go.

At the end is a letter that represents tolerance Where M=20%, K=10%, J=5%, G=2%, and F=1% D=.5% C=.25 B=.1%

Common surface mount coding

The third or fourth digit is the multiplier

Thus 103 is a 10K resistor

475 is a 4.7M resistor

Books on Resistor technology

Sadly, there are no new books on passives. The following are the best I've found.

• A Users Guide to Selecting Electronic Components by Gerald L Ginsberg

• Passive Components: a user's guide by IR Sinclair

A note to PC fascists

Before you email about the mnemonic, please remember that mnemonics need to stick in your mind. Of the dozens of alternative mnemonics that are suggested; non have, can, or ever will replace this one because this is the 'ONE people remember. The boys in this saying are called 'bad' - so it isn't promoting any kind of sexism. It could be condemned for being puritanical - but not sexist.

Methods of getting memories to stick is an art from Roman times - see http://en.wikipedia.org/wiki/Method_of_loci and http://en.wikipedia.org/wiki/Art_of_memory

Inducing a sexual imagery helps with memory. From Moonwalking with Einstein

"I want you to imagine Claudia Schiffer swimming in [a] tub of cottage cheese . . ."

Even the supermodel aspect dates back centuries: sexual images are more memorable:

"If you wish to remember quickly, dispose the images of the most beautiful virgins into memory places,"

advised Peter of Ravenna, a 15th-century writer on the topic.

Also, you might see Is a dirty mind a sharper mind?

If this mnemonic bothers you, I suggest that you make up your own.

Answers Questions

• What are the standard 5% Resistor values for one decade?

 The values are as follows.
 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91,

• Do resistors need to be put in a circuit in a certain way (positive, negative)? if so, how do I tell what end from the other?

Resistors Have no polarity; they can be installed either way, but it is best to put them in all facing the same way
so as to make reading them easier and to develop the habit for parts that do have polarity. Best to put the tolerance 
band on the right, while the reference designators on the circuit board are upside up.

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