Build you own Smart Electricity Monitor using the Arduino Yun or the Particle Photon.
A nice feature of the project is that the monitoring is flexible and it’s completely wireless (except for the Current Transformer of course), allowing continuous monitoring from a PC or phone and permanent storage on the Cloud.
Measured accuracy was 6% (typical), which is excellent for such a simple circuit. Even better accuracy was observed after calibration.
Detecting the frequencies of signals reliably is something that occurs fairly often in projects from guitar tuners to heart rate monitors, but reliable techniques to achieve this are often beyond the casual hobbiest because they involve digital signal processing.
I’m not saying it’s difficult. It’s not difficult. It’s just that you’d need to have studied DSP to know about frequency estimation techniques and the various tradeoffs to select the right one for your application, and many hobbyists haven’t studied DSP.
Here’s a project on using Autocorrelation to detect the frequecy of a signal. It works in noisy environments and is suitable for many hobby projects.
Reliable Frequency Detection Using DSP Techniques
One of the most popular projects on Google for an Arduino / Raspberry Pi Internet Radio is my project on Instructables. I’ve added that project below. It’s been implemented countless times and I’ve answered many queries on it, so if you have any questions please ask.
How to Make an Arduino / Raspberry Pi Internet Radio