Help making a CRT oscilloscope

[guskenny83]

Cool. I might get a couple of cores and a different gauge wire as well then to do the trial and error.

Thanks again for all your help!

 

[Old Steve]

If I were you, I'd put a 'Wanted' ad in the local paper for an old CRT TV, to use it's horizontal deflection coil as a dummy. You might be surprised how many are still laying around. I can't be the only one. Offer $20 - dead or alive.

 

[guskenny83]

I took your advice and found another old tv with a coil that i could use.

I stuck it in a box mounted on the side of the tv and now it works great!

Thanks again for all your help!

Cheers

 

[Old Steve]

Excellent, Gus. I'm glad you found another one. Much easier than winding your own coil.
I'll be interested to hear how your project progresses.

 

[guskenny83]

Its pretty much finished now.

here is what it looks like:

i mounted the coil and a small 3.5W amplifier with a pot to attenuate the signal into the side box:

the whole purpose of the project was to be able to visualise an audio signal that was put through it, so accuracy of signal representation wasn't very important.. here is what it looks like plugged in..

I mounted some rare earth magnets toward the back of the CRT to split the beam into its red green and blue components..

I tried to swap the vertical driver wires to the horizontal deflector coils, but it wouldnt give me the full screen width, so i left it vertical, i dont mind that much, it still looks good.

one added bonus from the project that i didn't think of when i was planning the it is that i now have an extra white noise source from the headphone jack on the TV, with its own amplifier and volume knob, so that is pretty cool too!

now i am having ideas of building a theremin into a box on the other side of the TV and using the in-built rabbit ears to control it, that could be pretty cool.. i could even use the original speakers from the TV to run it when no amp is available.. but that is an idea for another time.. this project has already been distracting me from my actual research work for long enough, ahahahah

thanks again for your help, i learned a lot (even if i didnt end up using most of the knowledge! hehe)

 

[Old Steve]

That looks pretty cool. You've done a good job. Nice neat appearance, too. Well done.
The theremin idea is interesting as well.

 

[CDRIVE]

I LIKE THAT!

Chris

 

[guskenny83]

Thanks chris!

It didn't actually end up being that hard. Just a matter of cutting a few wires and soldering.

The hardest part was actually getting a hold of two small sized CRT tvs. Even charity shops all have LCD screens these days!

 

[Old Steve]

Have you considered someting like adding a couple of small RC model servos to move the rare-earth magnets around, pulling the beams in different directions? It could probably produce some pretty interesting effects.

 

[guskenny83]

Yeah. I was thinking of using a couple of electromagnets positioned around the tube that could be triggered. But i was having so much trouble getting the thing to actually work at all with all the coil problems that i decided to go with permanent magnets.

Also, if i end up using it when playing live and moving it around a lot, i think as few moving parts as possible is probably best!

 

[CDRIVE]

Well, I totally agree with Old Steve. You do very neat work! I think you have a bright future!

RE CRT scarcity: If the Chinese think there's a buck to be made they'll manufacture them by the millions and list them on Ebay!
And as resourceful as they are I actually think they'll find a way to ship them in an e-packet with FREE SHIPPING!

Cheers,
Chris

 

[Old Steve]

Yeah. I was thinking of using a couple of electromagnets positioned around the tube that could be triggered. But i was having so much trouble getting the thing to actually work at all with all the coil problems that i decided to go with permanent magnets.

Also, if i end up using it when playing live and moving it around a lot, i think as few moving parts as possible is probably best!

Yeah, you're probably right. K.IS.S, as they say.