Since Martin from ctc-labs.de decided to close down his website, which was all written in German, I asked him for permission to translate and publish some of his content to keep it online and public for others to use.
So here is the translated article about his small and simple analog circuit that can be use to make a Tesla coil play music. Using just a op-amp and a 555 timer it is possible to recreate the effect from expensive MIDI modulators by instead just using a analog signal. This method is ofcause not as precise as with digitally microcontroller based MIDI interrupters.
Learn how to build your own Tesla coil and how to make it play music through a MIDI interrupter that can connect a computer to your Tesla coil in order to play music from just the sparks alone. It can be a hard start to build a Tesla coil if you have no prior experience in doing so, I recommend that you watch my video on how I learned to build Tesla coils and the history of how I started by building small Tesla coils up to my very large Tesla coil that can make 4 meter long sparks and play music while doing so. Besides the guide that I have listed here above, I have also developed a good deal of tools that can help you design and check if your components can be used in a Tesla coil. It is important to stay within the physical and electrical limits of the components, else you are at great risk of damaging them due to Tesla coils pushing the components beyond their specifications in order to get the longest sparks for the least amount of money.