Electronic components: The resistor

Well, I'm back from Barcelona, so it's time for a new post. This time about the electronic component: the resistor. As one of the most common components (you will find one in almost every circuit), you should be familiar with it. As the name implies the resistor has much to do with resistance. Because it's a rather big topic, today I will talk about the resistor, resistance is coming up next.

A resistor can be made of a few materials, depending on it's use. Most common is the carbon based resistor. A resistor has one big feature: resisting. So how much does it resist? That depends on the materials used. The color bands on the resistor will tell you how much resistance you can expect (with a slight tolerance).

The resistor in the previous image has four color bands: black, red, brown and gold. The first two bands will give you a number. Black is 0, red is 2, together this will be 02. That number is multiplied by the third band x 10. Brown is 1, so 1 x 10 = 10. If we multiply 02 with 10, the result would be 20 Ohm. The fourth band will give you the tolerance. Gold will tell us that the resistor has a tolerance of 5%. In other words, the resistor will have an actual resistance between 19 and 21. This is an example, you will not find any resistor with black as first band. Under normal conditions you will have no problem with the tolerance. I borrowed the following table from http://en.wikipedia.org/wiki/Resistor:

Color	1st band	2nd band	3rd band (multiplier)	4th band (tolerance)	Temp. Coefficient
Black	0	0	×100
Brown	1	1	×101	±1% (F)	100 ppm
Red	2	2	×102	±2% (G)	50 ppm
Orange	3	3	×103		15 ppm
Yellow	4	4	×104		25 ppm
Green	5	5	×105	±0.5% (D)
Blue	6	6	×106	±0.25% (C)
Violet	7	7	×107	±0.1% (B)
Gray	8	8	×108	±0.05% (A)
White	9	9	×109
Gold			×10-1	±5% (J)
Silver			×10-2	±10% (K)
None				±20% (M)

I find it easier to use a resistor calculator site like http://www.samengstrom.com/nxl/3660/4_band_resistor_color_code_page.en.html.

That concludes today's topic, thanks for reading.