The instructions are not the best, the picture of the finished product is to small to see the details & as to the large coil, no info on how to place it on the circuit board, just let it sit there or glue it down.

A fun little project to pass the time.

For the price, this was a pretty nice kit and well worth the money even just for soldering practice. This kit does NOT produce a 2 foot (or even 2 inch) discharge, if that's what you are looking for you need to spend more on a higher quality kit, but it does produce a small (~1cm) discharge that's visible even in a well lit room. The discharge will jump to nearby objects, light the included neon light or a fluorescent (CFL) bulb from several inches away, produce a small buzzing sound and a nice ozone smell. It also will play audio input to the audio connector via the discharge, it's not loud but is clearly audible.

I bought this for my 10 year old son. It's a fairly simple kit that we were able to assemble in an hour or two. Assembly was fairly easy if you have some soldering experience, handiness and a bit of a technical background and can identify the components. The components are tolerant to some extra heat and my son was able to handle soldering most of them. The instructions are not the best but there are not many components and it's fairly intuitive where to place them, just make sure you get the caps, LEDs and transistors in the correct orientation. Wrapping the secondary coil with the primary winding was the most difficult part, make sure you follow the directions (1.5 turns towards the bottom of the secondary coil with ~1.5mm air gap) and trim excess wire before you solder.

I am running with a 24V 4A supply and things work fine. Note that the transistors run HOT!!!!, at least at this input voltage. I used heak sink compound between the transistors and heat sink and even then I would only run this for a few minutes as the heak sinks become hot enough to burn you and I believe the parts will fry themselves if run for much longer.

My son was excited that it worked and it took 5x the time to assemble and probably provided 10x the education of a similarly priced Lego set so I'm giving this one a thumbs up.

I put it together in about an hour with my daughter. It may take you longer. I'm handy and used to building things. Instructions were adequate. After powering it, our expectations of a big sparking coil able to scare and terrify the neighbors was crushed. It was a rather small spark. We found a bigger power supply and tried again. Slight improvement. Well i guess for safety purposes you can't make these things too powerful. We were able to make a spark about 1/8" inch and light a candle with it.

Mine came with no instructions. The circuit board is labeled so I didn't really need them.
Supplied wire for the secondary was barely enough for one turn and it didn't work, needed to use my own wire to get 3 turns (as printed on the circuit board) for it to work. I made my own top for the coil and added a ground wire to hang the neon bulb from.