Most elements of this project were straightforward; however the current sensing proved to be a challenge. I wanted to keep this low cost and use what I had, so buying a current sensor was out and I didn't have anything suitable in my junk box. So, I toyed with the idea of deconstructing a transformer like Ron did, but couldn't find a suitable part for that either. Then I had an idea; make a transformer with a coil of wire! So, I bought a cheap coil of 30AWG magnet wire and wrapped a few turns of 14AWG TEW around it. The idea being I would pass the AC current through the 14AWG wire and measure the induced voltage from the spool of magnet wire. This worked, but not very well. I tried varying the number of turns and got better results, but still not what I needed for the circuit to function. Eventually, some of my transformer theory came back and I decided to experiment with core materials. As it turns out a 1/4-20 bolt was perfect! (It also made mounting the whole thing very easy). 

So, with a bolt through the middle of the spool I was now able to detect a reasonable voltage from my "transformer". I then set off to design a proper amplifier to clean this signal up and the project was finally off the ground!