You wouldn’t believe how easy it is to turn an old TV into an oscilloscope. Snip a couple of wires and switch them around, then add an input jack and you’re away. In the video I’m displaying the audio from the TV tuner, but you can plug in any source.

Instructions are here. Basically, your TV tube puts a dot on the screen. The dot is moved around by two coils (horizontal and vertical). Normally, the coils have a signal on them that makes the dot move from left to right and up and down a couple hundred times a second. Once you have found the 4 wires doing the magic, you cut them all. The two wires that come from the vertical part of the tuner are connected to the horizontal coil. The pair going to the vertical coil are attached to an input jack, so whatever you plug in there will be displayed.

Something I’d like to add in the future is a variable timebase, which would make this thing a whole lot more useful. It’ll just be a case of building a simple signal generator to feed into the horizontal deflector coil. Something like what this guy did.