Hello all, I'm currently working on a project and I have a question in regards to creating an efficient induction coil for our circuit. Without going into the specific details of the circuit(We aren't given the details anyways, just the circuit itself), it basically imitates a transformer. We are given two VERY THIN strips of wire 15m long which we can then create two coils out of. A primary coil and a secondary coil. SEE FIGURE When a ball passes through the coil(s) (either a metal ball or non-metal ball) the sensor gives a numerical output between 0 and 255 (or 1024 I don't recall off the top of my head) based on the strength of the sensed magnetic signal. This strength depends on how we "make" our coils, so this will also generate our "signal threshold" to determine whether the ball is metal or non-metal. That being said, I have to be certain that the coils aren't going to change or deform, in turn changing our "signal threshold". Now the heart of my question is, what is the most effective and efficient way to build this coil(s)? Again, the wire is extremely thin, so if I was to wrap it around an object like a highlighter, and then remove the highlighter the wire doesn't hold its shape as well as it should and falls out of place. Is there anything we could spray the coil with so that it will hold its shape, but at the same time not decrease the signal strength it generates? Should we be looking to wrap the coils as close together and as tight together as possible? Should we overlap the two coils? Can we tape the coils without ruining the signal? Any ideas/tips/suggestions/comments? Thanks again!