compuslave:
I know Ohm's law, have since I was 2. But, I don't know how to use it. All my experimenting life I have sought out the power supply I need, rather than make due with what I have. Well, no more. I need a power supply, 5V. I have all sorts of wall warts and old lappy bricks.How do I get 5V from say a laptop brick that is rated 19V. I know it's a stupid question, but I can't be the only learning disabled one here.
The easiest way to do this is to make a power supply that takes 19V in and emits 5V. A handful of parts will do this.
It doesn't tell you how to use Ohm's Law, of course. But this project doesn't really require it.
The wall-wart will be rated for some amount of current; Ohm's Law can inform us as to how that could change with respect to the new circuit it will be powering.