

AVR Programming Guides
We have some nice AVR code samples to share. Lots of AVR goodies like timers, interrupts, and pin I/O for the beginner. 

Watts Tables
Use these tables to help you determine how much various items in your house cost you by the day, month, and year. 

Saving Electricity
A list of a variety of ways to help you save money by learning how much it costs to run things. 



Read Your Power Meter
By reading your power meter you can get a good idea of how much various electrical devices cost you. 







Introduction to Resistors Page 1
The most important component to understand in electronics is the resistor. This is because we use the resistor to model much more complex systems. If you understand how to do "resistor math" then solving complex systems becomes much easier.
Lets review the basics.
 They come in various values that are expressed in Ohms.
 You can determine their value by using either a multimeter or by reading the colored bands on them.
 A resistor is used to resist current flow.
We need to introduce a new symbol because it is used extensively in electronics.
The symbol for an ohm is Ω.
Whenever you see Ω written down, you can say "ohm" or "ohms" if plural.
Here is the schematic symbol for a resistor, and some real life examples.
Schematic Symbol

Actual Image



Expected Values of Resistors
Resistors come in many different values from 1 Ohm to 10 million Ohms. Since it is very inconvenient to write 10,000,000 out, it is common to express the values of resistors in Engineering Notation. While engineering notation is a broad concept, you really only need to know 2 terms when dealing with resistors.
Name 
Multiply By 
Kilo 
1,000 
Mega 
1,000,000 
Kilo and Mega are the greek prefixs that mean 1,000 and 1,000,000 respectively. So if I told you that a resistor was 5k, then you know that I really mean this.
5k = 5 x 1000 = 5,000 ohms or 5,000Ω (pronounced 5 kilohms)
Likewise, 5M is the same as this.
5M = 5 x 1,000,000 = 5,000,000 ohms or 5,000,000Ω (pronounce 5 megaohms)
Some common resistor values are listed in the table below. You should be familiar with these values because you will see them a lot in electronics.
Name 
Value 
100 
100Ω 
1k 
1,000Ω 
2.2k 
2,200Ω 
4.7k 
4,700Ω 
100k 
100,000Ω 
1M 
1,000,000Ω 
Jason Bauer is an owner and programmer for Portforward.com. He's allergic to twitter and facebook, but you can find more of his articles in the Guides section.
 