Check out this posting over at Radiomuseum: http://www.radiomuseum.org/forum/how_to ... kings.html .

I find this quite interesting, and will definitely give it a try next time I have a tube that I cannot read the number on or identify easily by other means.

I'm curious from a scientific point of view how this works. It must somehow relate to the wavelength of light produced by an LED flashlight (oops, I mean "torch" ), but it is not clear to me why there would be some residual markings more easily detectable with a particular wavelength when the main marking is rubbed off. Anyone know why this works?

Tom

I tried it on some tubes with weak/missing markings. As expected the light did help on weak markings, so will sun light. No help for tubes with missing markings.

Maybe type of marking is different on European tubes?

Would like to see results from others.

http://www.youtube.com/watch?v=MBE6j_qeNp0

I think you can see more easy if you lock ,the led iluminate tube, with a digital camera, perhaps the include on most celular. That can transform infra-red to visible.

Same results here as Norm had. At least the LED flashlite helps when ambient lighting just isn't strong enough.

Bruce Webster

Doesn't work any better than any of the old methods.

Dave

I recently acquired a new Android phone. Its camera will detect stuff like TV remote controls and even light from a laser that is outside of our visual bandwidth. Used to pay lots of money for such an optical device

Ariston is right. If you can find a way to illuminate the tube properly, viewing it thru a camera may yield results. Most of the old markings involved a mild etching of the glass.

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