Using a LED Flashlight to show numbers on Tubes

[Carl WA1KPD]

Have not tried it but if it works as good as it looks, what a great idea.
http://www.youtube.com/watch?v=MBE6j_qeNp0
Carl
/KPD

[W1AEX]

Nice find Carl! The HL2 tube designation kind of jumped right out of nowhere when he put the light on it.

[ke7trp]

Thanks!

C

[KB5MD]

Incredible,

[WQ9E]

Thanks Carl!  That seems to work much better than the freeze and breathe technique.

[Opcom]

Is it due to the UV/short blue from the white LEDs making the numbers fluoresce
or
Is it an artifact of a predominately narrow bandwidth of light from the LEDs having a large energy in one part of the spectrum (in this case blue as a coincidence)?

Inquiring eyes want to know.

IIRC a nearly monochromatic light is well-appreciated in microscopy when things become small.

[k4kyv]

I don't have the multi-LED torch with pretty flowers on it like the one in the video, but I  recently  picked up a retro-fit LED bulb for my MagLite at one of the big-box stores.  It has just one LED and is supposed to work equally well with 2, 3, and 4-cell lights.  The batteries in the MagLite were so crapped out that the incandescent bulb would burn for about 20 seconds then fade out.  I didn't have any new batteries, so I tried the new bulb  with the old batteries just to see if it worked, and the thing was so bright it hurt my eyes. It was like a spot light. And it kept burning as long as I had it on.  A fresh set of batteries should last a long  long time. I plan to try it with some of my lost-ID tubes. I think the white LEDs are supposed to actually generate ultra-violet light, which is converted to visible white light with some kind of coating on the lens, much like the way a fluorescent light works. If it's the UV leaking through that does the trick, an old 60s-era "black light" might work even better than the LED. Maybe that's why bright sunlight sometimes works; it has plenty of UV, but the UV is overpowered by the visible light.

[ke7trp]

The LEDs require less voltage to run and some have a built in regulator.  They run HOT. VERY VERY HOT and the limiting factor for high power LED flashlights is the heat.  Failure of the LED itself is a problem if left on for extended periods. 

If anyone enjoys flashlights and or works at night outside or just wants a new toy, The Dealextreme website has a section of ultra flashlights.  You simply will not believe the 1000 lumen LED flashlights. It has to be experienced to be believed.   A 2D maglight has about 36 Lumens with FRESH batteries.  A 3D maglight is 120 lumens. 

The newer ultra LEDs at 1000 or 1200 lumens are in my opinion TOO BRIGHT.  THINK LOCOMOTIVE lamp or SEARCH and rescue helicopter light in your hand! Your friends and family will be shocked at these things.

They shine for MILES.  Great fun if you are out in the country to spot wildlife or maybe a Crook on your property.  You can get a pocket light that is 200 lumens that is brighter then a 6D MAG.


C

[kb3ouk]

That's why it says in the description of the video that it works best in low-light situations, not in bright light.

[WQ9E]

I think the white LEDs are supposed to actually generate ultra-violet light, which is converted to visible white light with some kind of coating on the lens, much like the way a fluorescent light works. If it's the UV leaking through that does the trick, an old 60s-era "black light" might work even better than the LED. Maybe that's why bright sunlight sometimes works; it has plenty of UV, but the UV is overpowered by the visible light.

I will borrow a UV LED flashlight later this week to try it versus my regular LED flashlight.  A colleague bought a UV light several months ago to locate pet stains on carpet.  If UV is the trick then this flashlight from MPJA should be a good choice:  http://www.mpja.com/Flashlight-UV-and-White-LEDs-with-LASER-Pointer/productinfo/17645+TL/

You can always personalize it with pretty flower decals

[WA3VJB]

.  They run HOT. VERY VERY HOT and the limiting factor for high power LED flashlights is the heat.  Failure of the LED itself is a problem if left on for extended periods.

C

Yes, I replaced the PR-12 incandescent bulb in a 6-D electric torch that I've had for years. It has a metal reflector (real mercury coating!) and this acts as a heat sink for the LED.

I also got the Mag-Lite LED replacement for a 3D Mag that I keep in the car, and it retains the focusing function of the lamp head, nice.

A couple of winters ago I noticed some cold weather startup dimness on the LED that sorted out after a while.  And, I've seen elsewhere that the heat build up actually attenuates the light output during use.

Interesting stuff. I like the lower current draw.

They had some "camping" LED lights at Timonium (Md.) hamfest that do real well on a trio of Double-AY.  I loaded two of them, and left one powered up overnight. Next morning, 8 or 9 hours later, there was still a useful amount of light.

[k4kyv]

If UV is the trick then this flashlight from MPJA should be a good choice:  http://www.mpja.com/Flashlight-UV-and-White-LEDs-with-LASER-Pointer/productinfo/17645+TL/

I ordered one of those. MPJA is a good company to do business with. I have ordered stuff from them from time to time for years. They often have little odds-and-ends parts for sale you never would have though you would ever see anywhere.

Only downside was that the shipping charges were more than the cost of the damned light.

[Edward Cain]

Thanks Carl.

I just used this trick to identify a 1L6. I've had the tube lying around and could not read even part of the number. My LED flashlight brought the number out. Have to have just the right angle.

Ed

[K9PNP]

Thanks.  Works at the right angle.  The tube was a 42.  Much worn.

[Opcom]

LED flashlight conversions are fun projects.

My first one was a 9-LED white one for proof of concept. The LEDs were $1.20 each at the time. The LED characteristics and schematic of the modded unit is here:
http://bunkerofdoom.com/wled/ledflashlight.html

Second was a 36-LED one and that was more LEDs than available in any flashlight at the time it was built.
http://bunkerofdoom.com/wled2/36_LED_flashlight.html
It uses a boost converter and a 6V lantern battery and 4 strings of nine 8000mCd white LED with a narrow 12 degree 1/2 angle beamwidth. No lens was required but aligning them all was tedious. An empty round "surveillance illuminator" circuit board designed for IR LEDS was used. It cost me $92 using all new materials, but a commercial product with 40 un-binned LEDs was $199 and with 60 was $299.

There was no such thing as a high power white LED, just ones rated 25mA @ 25 deg C. I believe we are a bit jaded today.

[k4kyv]

Hopefully the things are improved to-day.  My previous experience with LED flash lights was that the LEDs would begin to fail, one at a time, before even the first set of batteries fizzled.  I went through three lights before I gave up and went back to my trusty incandescent.  The Mag Light conversion has just one LED and it is brighter than the original, and obviously draws less current, since the expended batteries now work fine in it. I believe the LED package said 1 watt.  Not sure what the current drain is for a conventional incandescent bulb, but they do eat up batteries in no time flat.  I haven't tried deciphering tube numbers yet.

One method I have used in the past, which sometimes worked, was to rub the tube in my hair, then lightly wipe over where the type number was stamped. Then holding it in a bright light, sometimes the numbers would be readable.  Never had much luck with chilling the tube and letting it sweat when returned to warm air.

I have noticed that some stores scan all paper money with a UV light to detect counterfeits, and last time I flew, they scanned my passport with what looked like UV light (my DL has no photo, so they won't accept that; I paid $30 for an additional wallet size passport card rather than wait 3 hours at DMV to have my picture taken, and I don't want to risk losing my real passport). Evidently many things become invisible to visible light but not to UV.

At the Exploritorium in San Francisco, they have a little booth located under a sky light in direct sunlight.  The windows are coated with something that is opaque to visible light, but admits UV. Inside the booth, it appears completely dark, but the filtered sunlight fluoresces certain objects better than any black-light lamp I have ever seen, demonstrating just how much UV is in sunlight. No wonder sunlight craps out plastic insulators.

I just noticed the other day that one of those white plastic dog-bone antenna insulators you often see at hamfests, that have largely replaced real ceramic ones, has developed a soft grey surface layer of UV-degraded plastic, that I can scratch off with my fingernail. That has convinced me to use real porcelain insulators from now on for anything beyond temporary.

[Todd, KA1KAQ]

That's a neat trick to know, Carl. TNX for posting it.

I've had good luck breathing on the tubes enough to fog them a bit, or placing them in the freezer then removing them into warm air. This can make faded designations show up too. Will have to try the LED approach.

[KM1H]

Ive had mixed results with breathing and hair rubbing. Tried the Chinese LED Mag-Lite clone and recovered all I looked at so far as I hate to throw things away and some Ive had for decades. Nothing rare but all tested at the high side of good.

Carl