How To: Make a CRT TV Into an Oscilloscope

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Introduction: How To: Make a CRT TV Into an Oscilloscope

This is the simplest possible way to make a CRT (cathode ray tube) TV into an oscilloscope, it can be done in about half an hour.

Supplies
-A CRT TV (color may work, but I'm not sure)
-Some wire
-A soldering gun
-Rubber gripped pliers (for safety)
-A screw driver

Step 1: Identify Wires

After undoing all screws remove the cover from the TV.
Inside wrapped around the CRT are two coils of wire, one controls the vertical deflection of electrons, the other controls the horizontal deflection.
Find where these coils of wire attach to the circuit board, and desolder one coil.
Place the cover back on the TV(for safety) and plug in and turn on the TV.
If you see a horizontal line, you desoldered the vertical deflection coil.
If you see a vertical line, you desoldered the horizontal deflection coil.

Step 2: Placing Wires

Desolder the vertical coil if you haven't already and attach extra wire to the vertical coil, this will have to be long enough to come out of the TV so you can attach a voltage source.
Now desolder the horizontal coil, and solder it to where the vertical coil was.

Step 3: That's It

Really, it's an oscilloscope now.

Step 4: How to Use It With Music

I use mine to watch the waves created by music from my mp3 player
First take an old pair of headphones and cut one off, then strip away some of the insulation.
Now you should have multiple exposed wires, one will be slightly thicker than the others and wll have a thin coating of insulation on it - scrape it off.
Attach this wire to one end of the vertical coil, and the small group of wires to the other end.
Now plug it into a sound source, remember your attaching your mp3 player (or whatever) to a giant coil of wire, and there's chance it could break.

6 People Made This Project!

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131 Comments

Hi ..?
This is the third TV burnt !! ?
It was showing that line and then after 7 minutes suddenly disappear! it is happening every time
Why that does not work with me?
The TV is working but the screen is black.
The horizontal coil supposed to handle the 60hz what is the wrong ?
I even could not try that circuit you suggested ...

Sorry I took so long to respond! And I'm sorry about all the TVs; that's too bad.

The TVs don't work at all any more? And does anything actually burn? Do any components inside look like they failed?

Moving the deflection coils shouldn't make anything change in a way that would break the TV

no problem
actually I finally did it! and I find out what was the problem
thank you very much for your help :) and your instructions.

Hello! I think I got the same problem as you at the time.

I can't get no line or point... The Tv is on, but the screen stays black. On the front panel the led blinks, wich is not habitual...

Do you have any idea? Is my Tv not old enough? I tried on 3 different TVs and only on of them works just fine (apparently the oldest one).

Thanks!

Tim

Try connecting a "dummy" coil to the disconnected output. Try to choose a coil of similar impedance to the yoke. (1-2mH, 5-10 ohms).

Next time try using a small black and white unit. The simpler the better.

This is so cool, I found this old tv years when clearing out a storage room for my old employer. I'm gonna try to do this, but I'm very new at soldering, so I think I might try another project first. This one has a jack input behind for receiving signals. Maybe I could reroute it for the oscilloscope input?

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I nailed it second try. Really easy and fun nice instructable

hi! I've already done this with an old crt tv but I was wondering if it would be ok to connect the tv's own audio wiring to the coils so I can just input an audio signal (somewhere in the circuit) and use the tv's own amp to drive the coils, I haven't done it yet because I think it might be dangerous but what do you think?

I like the idea! If you find the speaker(s), it should lead you right to the TV's amplifier, and if it's an integrated circuit (a chip) you might be able to look it up online for more info.

There's always danger working inside the TV because of the high voltages. As for this specific modification, the amplifier is not designed to drive the deflection coils. This could potentially lead to excessive heating which, in the worst, case means fire! I don't think that's particularly likely, but if you try it, be safe!