An arduino based watt meter. Crazy, right? What would you do you use a microcontroller for in a watt meter? The answer would be nothing if you were to go buy one. But my answer is it is the brains behind your meter.
The concept came to me pretty much randomly one day at my desk-job. I was bored out of my mind when the thought came to me to make a watt meter. I dismissed it as a whatever project, not really thinking much about it at the time. Fast forward a couple months, and I revisited the idea and realized i could easily make this. So here we are, me making the meter a reality.
The circuit is actually pretty simple. You have the Pro Mini driving the display(this is the main reason why i needed a microcontroller, was to drive the LCD). Then you have an ACS712 passively measuring the current draw. The output is an analog signal sent to the Mini that will then process the input, run a quick calculation on it, and output the watts in real time. This design went thru a couple of different design revisions. The first one included an on-board voltage divider to also get the voltage. This was dropped because this would be tapped directly into my outlet, so it will be nearly constant at 120v. This value would just be a constant in the code. The current revision does not have a divider on board, and that is the design im moving forward with. The rest of this log will outline the layout of the circuit as well as possible future expansions. Come along for the ride!