CRT audio visualizer when the LEDs are not working

It’s been a recurring feature of consumer audio equipment ever since the first magic eye tube flashed to life, to get some kind of visualization of the sound being played. More recently, that meant an LED array or an OLED screen, however [Thomas] Better than this went with a CRT TV Converted to perform a rudimentary oscilloscope.

The last generation of commonly available monochrome televisions were small 5-CRT models made in China. They never received digital tuners so digital TV has become the standard and is now useless to most people. Thus they can often be found for pennies at the flea market.

[Thomas]The hack involves taking out such a TV and retaining its circuitry, but separating the line operator from the deflection yoke. This will usually leave a vertical line on the screen as it will then be transmitted only by the frame driver at 50 Hz for PAL or 60 Hz for NTSC. By connecting an amplifier to a speaker with a line deviation yoke, he obtains a low-quality oscilloscope. Its use as an instrument would be limited, but few others had such a great imagined sound. It’s viewing the screen in portrait orientation, we’re tempted to turn the handlebars to get a landscape view.

It should be noted as always that CRT TVs have high voltages, so we suggest reading up on how to treat them with respect.