There are a few Instructables and otherwise internet based instructions on how to modify a television set into an audio visualizer or other simple oscilloscope-like device. This Instructable will show you how to create an actual lab oscilloscope worthy of a poor, amateur electronics enthusiast. The final product has optional audio output, variable input voltage from millivolts to hundreds of volts, as well as manual horizontal frequency locking. The total cost for this project was around $20.
To give proper credit, this Instructable is an improvement on Magnelectrostatic's at http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/. I wouldn't have been able to complete my mod without it. Thanks!
UPDATE (12-28-10):
This mod is not capable of displaying much outside the human audible range (20-20k Hz).
Also, since TVs are highly variable in design, this Instructable is intended for people who can do their own experimenting. This of course requires experience in electronics. Your TV will probably be different from mine. My instructions may not apply to what you're working with. They're guidelines. I hope they help you modify your available resources by providing ONE particular example.
To give proper credit, this Instructable is an improvement on Magnelectrostatic's at http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/. I wouldn't have been able to complete my mod without it. Thanks!
UPDATE (12-28-10):
This mod is not capable of displaying much outside the human audible range (20-20k Hz).
Also, since TVs are highly variable in design, this Instructable is intended for people who can do their own experimenting. This of course requires experience in electronics. Your TV will probably be different from mine. My instructions may not apply to what you're working with. They're guidelines. I hope they help you modify your available resources by providing ONE particular example.
Remove these ads by
Signing UpStep 1: Safety
This project involves working in close proximity to the television's exposed flyback transformer and high voltage capacitors, which are both potentially lethal devices if you do not take proper safety precautions.
First, the obvious step: Is it plugged in? Unplug it! Isn't it funny that this is the exact opposite of what a tech normally tells you...
When you remove the shroud, be careful not to rip any wires from the circuit board, and do not touch any of the exposed contacts. Identify large capacitors and take note of their voltage ratings. 50v and above are especially dangerous, and should be discharged with a well insulated screwdriver across the contacts prior to tinkering if possible.
UPDATE (12-28-10):
Ok, ok, I generally dislike disclaimers because they are almost never legally sound. But for those of you who don't get the idea from the above paragraphs...
Don't attempt this unless:
you have a solid grasp of high voltage safety practices.
you have a solid grasp of electronic equipment in general.
you have someone around to call 911 or give you CPR.
you have experience working with mains (120VAC) power.
you are not a moron.
I take no responsibility for damage to your health or equipment. All damages incurred are the sole responsibility of the end user.
First, the obvious step: Is it plugged in? Unplug it! Isn't it funny that this is the exact opposite of what a tech normally tells you...
When you remove the shroud, be careful not to rip any wires from the circuit board, and do not touch any of the exposed contacts. Identify large capacitors and take note of their voltage ratings. 50v and above are especially dangerous, and should be discharged with a well insulated screwdriver across the contacts prior to tinkering if possible.
UPDATE (12-28-10):
Ok, ok, I generally dislike disclaimers because they are almost never legally sound. But for those of you who don't get the idea from the above paragraphs...
Don't attempt this unless:
you have a solid grasp of high voltage safety practices.
you have a solid grasp of electronic equipment in general.
you have someone around to call 911 or give you CPR.
you have experience working with mains (120VAC) power.
you are not a moron.
I take no responsibility for damage to your health or equipment. All damages incurred are the sole responsibility of the end user.
Visit Our Store »
Go Pro Today »
without conection the horizontal deflection coils
i have a tv and it does not funktion without them
and i need an x and y
Is there any circuit that might be able to do that?
The audio source physically deflects an electron beam in this mod. If the deflection coils are complex or have other circuitry attached to them, this might not work. I've tried this with computer monitors before and I ended up with a oscillating thick line. I couldn't figure out how to make it work.
So is there no hope for this tv set!?
Brofist!
The Vertical coil is usually driven at about 80-130 volts peak.
You should be aware, that the Horizontal coil is wired in parallel with the flyback transformer, and the high voltage will change when removing the coil from the circuit, raising or lowering the high voltage (usually the latter)
The highest voltage you'll find in a TV set is the EHT Flyback connected to the picture tube via the thick cable in a suction cup looking thingy. On a B/W set you'll have approximatelt 10 Kv (Kilovolt) on this, and on a Color monitor Approx. 25 Kv.
I have done this mod a couple of times, and have replaced the Horizontal coil with an other inductor to keep the circuit working correctly. Around 400 uH of inductance should do it.
I added a Schematic cutout showing the Horizontal coil connected across the Flyback.
now the questions for you both, I have a 5.5" black and white plustron TV/FM radio that runs on 12V, Same kinda thing as used here, single channel that needs to be tuned each time.
The wires from the board to the coils are labled H1/H2 and V1/V2, that saves a bit of work but now I am wondering about the amp ciruit, is there anyway to make it run on 12V, it would be really nice to have the whole thing on 12V to save on transformers and also run it from a battery if needed.
I will of course be doing model specific instructable, Aeternusjunk, would you mind if I used this build as a foundatio, use the odd paragraph here and there?
Great work dude!
The main problem with a 12v power supply is the op-amp used in the amp circuit. Everything else will be fine, but the TL082 requires a minimum of +/-7v to operate properly. This means you'd need at least a 14v battery to run the amp. So close, yet so far. It might still work, so test it! However, there are low voltage op-amps such as this one that would be a good replacement. Basically you are looking for a 2 channel, through hole, dip-8, +/-6v supply (or lower) op-amp. Anything that fits that description should work. If you're running things from a battery, just chop off the AC rectifier section and you're gold. This is everything before and including the 4 diodes, but I recommend keeping the filter capacitor.
Wouldn't this let you choose the frequency, giving a lot more flexibility and make it more useful?
Or is that just so complicated that it isn't worth it?
The other problem, as I'm now realizing (or re-realizing) is that any signal of high enough frequency to warrant preserving the high horizontal scanning frequency will itself be very high frequency, subject to the impedance of the vertical deflection coil. You would need a another independent flyback transformer just for your input signal. This sounds like a lot of work to me.
I think I'm going to need to severely modify some things, considering the ancient monitor I want to use dosen't have a full image displayed.
Ill let you know what happens.
If it makes a difference, it's a 5.5 inch b/w portable tv...
Thanks!