Re: What to do with an old CRT
Tesladownunder, Sun May 28 2006, 04:30PM

1: Make a spinthariscope with the CRT phosphor. Also need a magnifying lens or eyepeice and the alpha emitter from an old smoke detector.

2 Make a vacuum chamber as in Jochens vacuum page.

3 Make a lifter supply (if you have the whole monitor with functioning HV).

4 Strip it of useful parts like the flyback, capacitors, mains cord, speaker or whatever but release the vacuum first by breaking off the pointed tip first under a cloth.

Peter

Re: What to do with an old CRT
Hazmatt_(The Underdog), Sun May 28 2006, 06:00PM

Because you want to use the tube:

1. Make a cool CRT clock like the ones made from Oscilliscope tubes

2. Make an oscilliscope

3. HEHE Make Pong

4. Make a cool Lissajou demonstration for kids to teach them about frequency division, harmonics, and all the cool old information that is now lost or burried.

I would love to do this with 2 lasers and make a laser light Lissajou show for the science center on campus. We would also incorporate sound as a fundamental of a concert A so the kids can hear how frequency, sound, and light all relate to one another. I think its a real hard-core demonstration of principles and understandable at the same time.

Re: What to do with an old CRT
Maz, Sun May 28 2006, 10:33PM

now how would i be able to make an oscilloscope?

Re: What to do with an old CRT
Hazmatt_(The Underdog), Mon May 29 2006, 08:45AM

how is a different thread

Re: What to do with an old CRT
Bored Chemist, Mon May 29 2006, 08:47AM

"Make Pong"
I thought that was chemistry.
A 'scope would be quite tricky because these things are designed for magnetic deflection. The frequency response would probably be rather limited.

Re: What to do with an old CRT
Alfons, Mon May 29 2006, 03:06PM


Watch and for instructions how to turn a television in a scope... maybe you'll find some inspiration there

Re: What to do with an old CRT
Tesladownunder, Mon May 29 2006, 03:47PM

At least I have done 3 out of 4 of my suggestions. Who has made an oscilloscope, PONG or a Clock (without using the CRT as a simple computer monitor)? Hands up please
I may need to use the electron gun out of one as my electron gun out of my x-ray tube may be too big for the standard glassware.

Peter

Re: What to do with an old CRT
Philcogrump, Tue May 30 2006, 02:42AM

I raise my hand for all three...


No, actually, I think you have it in reverse. Almost all oscilloscopes use electrostatic deflection, not magnetic deflection. Electrostatic deflection has much faster response than magnetic deflection, which is why it is used for many oscilloscopes and at higher frequencies. Magnetic deflection has its limitations at certain frequencies. I built a simple scope using a 2AP1 CRT and three tubes. I also even have a commercial scope from the 40s that only had the CRT and one tube. These things are EASY to build methinks.

What kind of CRT do you have, Maz?

Re: What to do with an old CRT
..., Tue May 30 2006, 03:48AM

Umm, I believe you misread the post...

the tube from his computer monitor (implied in the first post) uses magnetic deflection, which makes it poorly suited as a scope.

I would just strip it for parts, or combine it with an old junker computer and give it to a relative for their b-day, or if you are lucky you can donate it to the salvation army or local thrift store, then write it off on your taxes for like $50, then get 2/3 of it back

Re: What to do with an old CRT
Bored Chemist, Tue May 30 2006, 08:02AM

"Umm, I believe you misread the post..."
Yes, he did.
I like the idea of writing it off against taxes.

Re: What to do with an old CRT
Self Defenestrate, Tue May 30 2006, 01:48PM

Haven't tryed it myself, but looked cool. The CRT Vacuum Pump

Re: What to do with an old CRT
Billybobjoe, Wed May 31 2006, 12:36AM

Would it be possible to make a weak X ray tube from one? The thick lead glass on the front may stop a bit but if you upped the voltage I bet you could get a decent amount from the front of a small one with thinner glass.

Re: What to do with an old CRT
Philcogrump, Wed May 31 2006, 03:55PM


I don't see any implication that the CRT came from a computer monitor. I naturally assumed "old" CRT meant like a real oscilloscope CRT.

Well, anyway, if it was that kind of CRT, then sadly I'd suggest using it for target practice.

Re: What to do with an old CRT
Bored Chemist, Wed May 31 2006, 05:57PM

Roughly what fraction of the worlds CTRs come from 'scopes rather than TVs or computer monitors?

Re: What to do with an old CRT
Steve Conner, Wed May 31 2006, 08:35PM

2/3, in my house at least.

Re: What to do with an old CRT
..., Wed May 31 2006, 10:14PM

As far as how many produced, I would say about 99.9% of tubes are electromagnetic... (computer monitor or tv) Although that number will drop now that lcd's are becoming more popular...

Re: What to do with an old CRT
Bored Chemist, Thu Jun 01 2006, 06:14PM

"2/3, in my house at least."
OK, so it's 3/5 in my house (and an interesting question if I am using my computer monitor as a 'scope), but I don't think that's very representative of the world.
Anyway, the most fun I had with an old CRT was throwing a brick through it, but I wouldn't recommend doing this in a bedroom.

Re: What to do with an old CRT
Bjørn, Fri Jun 02 2006, 04:35AM

Philcogrump is correct in that the first post does sound like it is a bare CRT. Just by looking at the post my guess was that he was talking about a computer monitor. Who puts a CRT in the middle of the floor and how does he know that it is working? In addition he cuts corners with capitalization and spelling so he would use "CRT" instead of a more correct and longer phrase.

I find CRTs to be rather boring. The only thing I have used one for is to store shadows of scary events using a flash. Now that digital cameras are everywhere it would not make sense anymore.

Re: What to do with an old CRT
Maz, Sat Jun 03 2006, 01:44AM

I know it still works because i have tried it. I did not capitalize CRT on accident before. And, if anyone wants anything off of it, just PM me because other than sitting in my room, it is doing nothing. Bjorn, you sounded condescending, there is no reason for it, and no reason for you to be edgy towards me. Assumptions were made on all parties.
"In addition he cuts corners with capitalization and spelling so he would use "CRT" instead of a more correct and longer phrase."

But it still doesnt make a difference, a crt is a CRT. I know you are a mod, and I dont really care. If you do not have anything to contribute to the thread, please do not post.

Everyone else, thank you for your help.

Re: What to do with an old CRT
Bjørn, Sat Jun 03 2006, 07:03AM

You still have not made it clear if you have a cathode-ray tube or a computer monitor in the middle of your room. Since you don't protest when people assume it is a computer monitor I conclude that in this case a CRT is not a CRT but a CRT monitor.

The use of third-person in my previous post made it sound more condescending than it was meant. Any edge was entirely on purpose and caused by lack of care on your part. If you had cleared up the confusion after the second post instead of letting it run for almost 20 posts it would not have been needed.

Re: What to do with an old CRT
Maz, Sat Jun 03 2006, 02:48PM

CRT monitor bjorn.