I was just cruising around and was surprised that I couldn't find this info posted anywhere ... covers a more technical end of micro-electronics and I couldn't really find a forum that actually FIT for this info to go other than misc topics.

This is more of a "tool" than anything, but it should help you in determining exactly how much resistance you will need to power those awesome crystal chamber LED's or accent LED's if you're broke like me and don't have a board with built-in resistance!

**The formulas of Ohm's Law**

Ohm's Law can be rewritten in three ways for calculating current, resistance, and voltage.

If a current *I* should flow through a resistor *R*, the **voltage ***V* can be calculated.

*V = R × I*

If there is a voltage *V* across a resistor *R*, a **current ***I* flows through it. *I* can be calculated.

*I = V / R*

If a current *I* flows through a resistor, and there is a voltage *V* across the **resistor ***R* can be calculated.

*R = V / I*
Calculator can be found here:

http://www.the12volt.com/ohm/ohmslawcalculators.asp
*Calculator page updated, courtesy of Azmaria and Google

Determining the values of your Carbon Film Resistors:

The last band of the resistor is almost always going to be either Gold or Silver, and so you can determine the direction that you should start reading from by this.

First and second colour bands:

- Black = 0
- Brown = 1
- Red = 2
- Orange = 3
- Yellow = 4
- Green = 5
- Blue = 6
- Violet = 7
- Gray = 8
- White = 9

Each band represents a digit, and so a Resistor with a Brown and then Black band would equal a value of 10. A White and then Blue band would equal a value of 96.

The Third colour band:

- Black: x1
- Brown: x10
- Red: x100
- Orange: x1K (k = 1,000 ... 1K = 1000)
- Yellow: x10K
- Green: x100K
- Blue: x1 meg
- Silver: /100
- Gold: /10

The Fourth colour band (Represents % Tolerance):

- Gold = 5%
- Silver = 10%
- None = 20%

Example Resistor: Orange, Blue, Red, Gold

3 and 6 (36) x 100 = 3600 ohms -5%

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