Hacking an old CRT TV to show sound!
As you may know, I’m discovering the world of modular synthesizers. I’ve been following LOOK MUM NO COMPUTER on youtube and he had this video on how to turn an old CRT screen into an “oscillograph”.
The idea is quite simple. You have the electron beam which is coming from the back of the tube. Where it hits the front of the screen, you see a bright dot. Two coils can generate a magnetic field that deflect the beam in the X and Y directions. By cutting the wires to those coils and connecting your own voltages, you can thus make the beam go wherever you want! Easy enough! Since these coils are rather low-impedance for audio-frequencies, I needed an additional amplifier to generate enough power. I found a small amplifier module on Amazon for about EUR 12, which I squeezed into the TV chassis. For some very convenient reason, the TV has its own 12V DC power supply internally, which I connected directly to the amplifier module. Don’t ask me why this TV has this. It was available on the back panel (not anymore!). Maybe for an antenna or something? Anyway, this is what that dusty old TV looks like on the inside now:
Now, we just connect two different signals to the X and the Y inputs, and we can make psychedelic curves.
And of course, don’t try this at home!
My friend and modular synth magician Melawati demonstrates the result here: