Hi i was wondering if i could hook up a 120v transistor (don't know if i should use pnp or npn) to my home lights and pmw it with my arduino. Eventually i want to be able to do this remotely, possibly by an ethernet shield.
as the wiki will explain this a method to automate your home and may be adaptable to your situation
a few links to Arduino projects and you about ready , as above use extreme caution when dealing with mains power
You might also want to take a look at this; http://www.youtube.com/watch?v=8xONZcBJh5A&feature=channel&list=UL
So I would still recommend you staying away from this project until you know a lot more about electronics and the danger of high voltage. And I would encourage you to wait even further on the part of doing this remotely as you might as well build yourself a device to remotely burn down your house.
Safty should be my priority, thanks for pointing that out. I have never done something on this big of a scale.
First. DONT DO IT unless you know what you are doing!
Then, what you want is an opto isolated dimmer circuit. I saw them as a kit once, and even prebuild modules, but a quick google session only revealed a few links, and none to a shop with prebuild ones.
The last link does actually look like a module that does what you need, but with a manual in Thai I cant tell for sure.
I will look more into that
If you are very careful and start with one lamp then you could try it using a relais shield or a relais.
It is important that you have a galvanic distinction between the Arduino and the home electricity. This can be achieved using a relais.
Make shure that you know how much Ampère the lamps draw. You might make some calculations. Better don't drive the washing-machine using this shield...
...and don't forget to make a cool picture if you burn and melt the tinkering. Good luck.
I never thought of using a lamp. Maybe I could use a flashlight or some other battery powerd light instead.
The shield Nils mentions here is probably your best bet. It's rated for up to 360v AC, which could handle an electric dryer if (as Nils points out) current weren't an issue. This is the route I would go.
Judging by how you formulate your question, you probably should not mess around with 120V. It can be quit dangerous and might even kill you.