mandag den 13. maj 2013

Sony Watchman Oscilloscope Hack

This is a demonstration of how you can turn any CRT-television set into a nice visualizer/oscilloscope.
Please take caution when opening up any TV with Cathode Ray Tubes as they can store thousands of volts for a long time after last usage. Use rubber-gloves and ground yourself as a minimum protection. Stay away from the anode (the suction cup hose) as this is the mofo responsible for storing these high voltages.

I take no responsibility for any accidents caused by this guide.
When that's been said - I've fiddled around with quite a few TV-sets during the last couple of years and I have a weakness for very small TV's, so when I came across this Sony Watchman from 1986 (this thing is as old as I am!) which I'd never heard of before, I had to have it as I thought it would be neat as a portable oscilloscope or visualizer for my setup. I am thinking of getting some more of these small CRT's for built-in oscilloscopes in some of my future DIY-synths!

The image to the right shows the Watchman as it were when I bought it, I thought it would be shame to tear it out of its original casing so I decided to keep it intact.

disassembled watchman
gaining access to the PCB
hack done! 

In the beginning I wanted just to have it display the horizontal axis for this traditional oscilloscope-mode but the ray is very narrow this way, only taking up a fourth of the area on the screen so I attached a switch for selecting wether to send the signal to both the horizontal and the vertical axis or just the vertical (signal to vertical axis = horizontal line. Check the wiring circuit further down)
This way it functions well both as a visualizer, showing galaxy or whirlwind-like formations or as a small waveform display.

Here's the final result:

For anyone urging to try it out, I made this circuit which should make things a bit more comprehensible. Wire-colouring of the axis' differs for each TV-set but should be easy to locate as they are attached to the end of the tube. And again: DON'T GET ELECTROCUTED!

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