toddthefrog wrote:OK now I'm a tid bit confused because I thought the resistor only effects the current and not the voltage. So you're telling me a resistor effects both? If I have a 12V (like I do on this board) in and need to power a 2.2 volt part (the LED) I can just plop a resistor on there and not have to use the linear regulator?

Current Resistance and Voltage are all related though Ohm's law V(voltage) = I(current) x R(Resistance)

Therefore if you change the resistance, current, or voltage the other two components of the equation will also be affected. Adding your resistor restricts the flow of current and drops some voltage. As a general case if you have 1 volt dropping across a 1ohm resistor there would be 1 amp passing through your resistor. If you double the resistance then you have 1 volt/2ohms = .5 amps.

Take some time and read up on Ohm's Law and Kirchoff's Current and Voltage Laws. (wikipedia might help) They will help you understand some of the effects of what you are doing. I took this class as a freshman I think you will be able to pull some useful information from the website. The lecture and powerpoints data should be useful you might be able to find some practice problems within the homework but it looks like a lot of that has been moved to a restricted location online.

http://www2.tech.purdue.edu/ecet/courses/ecet107/Everything in exam 1 and 2 is pretty good stuff. exam 3 is still good but gets more difficult.

One more key note, Power(W) = I x V So before you go dumping 1amp through a 1ohm resistor note that you'll be using 1Watt of power and that little resistor (more than likely limited to 1/4W) will burst into

flames.

(yay new forums)