This is a demo of the Dekatron sequencer driving a DIY tube synth.
The clock circuit includes a relay which clacks away somewhat charmingly.
The relay noise does not get into the sound path of the synth, it is just the noise the synth makes whilst operating.
Sound is recorded over the camera’s microphone so you all can enjoy 60 seconds of clack clack clack clack clack.
More info here – http://www.sdiy.org/pinky/tube2/tube_2.html
If you want a tube synth and don’t want to risk zapping yourself – http://www.metasonix.com/