Newbie Question

Hi all,

I am looking for information, for I have zero experience with Arduino. Is there a unit that can test voltage so that I can record it? For instance I want to create a device that I can plug into an electrical outlet and then plug a lamp into that so the lamp works. I want to figure out when the lamp is off and how much power it draws when it is on.

Thanks Ralph

rkrausse you have to get more experience. your project is possible but never never and NEVER play with the 220/110V of your house please start from the beginning (google: tutorial arduino or similar) and after a few months come back here for advice on your project

A safe, though roundabout and inefficient, way to do the on/off sensing is to put the lamp on a switched outlet, such as a power strip. That power strip will also have a 5 V (assuming you have a 5 V Arduino, otherwise 3 V) power supply (like a phone charger) also plugged in. You turn the lamp on via the power strip, which also turns on the 5 V power supply, which is detected by the Arduino. Of course that doesn't directly tell you power draw but that should be a steady value. If you get a device such as a "kill-o-watt" you can just measure the current of the light once.

You could also detect lamp on/off using a photoresistor but you'll need to make sure that it wouldn't be falsely triggered by external light sources, such as sun coming though the window, while the lamp is off.

Google “wattmeter with Arduino” and you will find lots of ideas and even some YouTube videos.