If you're going to do this, be careful, as your fingers get close to operating high voltage devices & potentially fatal current! Remember that TV's can store a lot of energy for a long time, so don't be poking your finger everywhere - even if the TV is off.
The 9mm headphone jack can be bought from RadioShack, and the oscillator was producing a triangle wave at 30 Hz, not at 330 Hz.
Oops - it's not an 'electron ray' that the electron gun makes, it's an 'electron beam'.
Have an iPhone? Check out all 200+ new features coming in iOS 13.