After my parents got me a Strobo-Spark for Christmas, the first thing I had to do was adjust a coil on it. I got this one right on the money, and I decided to take a slow-motion video of it via my iphone's slow-motion feature. I think it looks really neat, and you can certainly tell that that coil is not double sparking!
I just wish that my iphone could take better quality videos!
https://www.youtube.com/watch?v=HD1cz2ip7lc&feature=youtu.be