ElectroCandle

Here's the idea:

Sort of a Hybrid LED 'Candle' and phosphorescent plastic tube:

A high efficiency circuit activates some LEDs every few hours to 'recharge' a phosphorescent plastic. The LED's output wavelength is the most efficient for 'charging' the GITD plastic.
Also a high flux single LED on the top for a brighter light if needed. The 'candle' is a round tube about the length of 2 AA cells, with 3 LEDs pointed at itself.

The GITD material needs charging every hour say, for 10 minutes (is that even close?), since its not really going to be used as a flashlight a really aggresive PWM duty cycle could be used... 50 Hz flicker won't bother a phosphor...

With every electronics trick in the book, how long do you think the runtime would be?

On say 2 AA Alkalines? (3 low power monochromatic LEDs for example)

(assuming of course LEDs can charge up these materials efficiently)

Thoughts? Ideas? Constructive critiscism is welcome.

UV should be good for recharging G.I.tD.

That's a very intrguing idea. I'm just not sure it would be truly efficient.


What's the designed function?

Are we looking to create a locator? In that case, would an automatically charged GITD system be more effecient than a slowly flashing single LED?

Is the idea to create a soft, night-light level of illumination--just to show you where the door and the wall are? In that case, I would think that an "indiglo" system would be more efficient.

All you are doing with the phosphorescent material is delaying the distribution of the light produced by the LEDs (well, you are also changing the wavelength and the distribution characteristics)--so when you factor in the light losses due to the GITD material I think you'll actually have a LOWER effeciency than if you ran your LEDs constantly at a lower power level.

I had not considered the UV angle--The GITD material would take in UV light and output a different wavelength--is there an effiency advantage to that??

I think this is a neat idea, and the finished product would certainly be cool.

I think it if was a general light to use for ambiance it would be sweet..

Actually, I think this is a interesting idea. One of the things that happens with the glow-in-the-dark stuff is that it can essentially produce a monochromatic light that is at the ideal wavelength for night vision (green to bluegreen). Another nice thing about this is that the light would "collect" any ambient light and give it up slowly in the darkness, thus supplementing the automatic charging.

With the periodic "charging" using a UV LED, the lifetime of 3 or 4 AAA batteries would probably be similar to their shelf life. Using only a couple of AA batteries would require a boost circuit which would rob you of some of your efficiency. On the other hand, you may need the additional "push" of AAs if you add the external high output LED.

I've played with something similar to this using a UV LED embedded in a mix of epoxy and strontium aluminate glow powder.

This would not, though, be very bright.

Good luck.

Mark

Sort of a Hybrid LED 'Candle' and phosphorescent plastic tube:

You read my mind!!! I have been doing some playing around with GITD powders from "Glow Inc" and have cast some different shapes out of cystal clear epoxy. (Perma Poxy a Permatex product) Shapes like small diameter rods, hex shaped bars, coin shaped tabs and spheres. A sphere with a UV light source cast into it and powered by some high efficiency controller to time multiplex the light delivered to the UV/GITD sphere could cause it to glow fairly bright. Depending on how long it took the UV source to charge the UV/GITD sphere to a useful brightness and what the drain would be on the source powersupply would determine efficicency. I have found that ultra green GITD powder from "Glow Inc" have the brightest initial glow but fades fast, ultra blue is all most as bright but keeps is brightness level longer than the ultra green. Maybe a ultra blue/epoxy sphere would be a good choice for a test device. There are some very low power draw circuits that "BEAM" hobbyist use to flash LEDs from solar cells charging mega capacitors. (1 to 5 Farad) I would be very interested in working with anyone on the testing and development of some Electro/UV/GITD device.

Gary

Indeed, either great minds think alike or we've all had the same really bad idea:lolsign:


Also Can glow powder mixed into epoxy be charged 'from behind', as in:
have the LEDs on the inside of the (tube/sphere) and the epoxy/GITD mixture on the 'outside'?

The idea behind AA's was that they have MUCH greater energy density than AAA and its going to have alot of electronics anyways, so why not go for high efficiency conversion.
(there are chips out there that get 95%! )

Also:
'NP-2820'
http://www.nichia.com/product/glow.html

2 Minutes to charge it in UV, and it glows for "15" hours.

They also make UV LEDs that would put out the right wavelength of light too.
:candle:

**** Also Can glow powder mixed into epoxy be charged 'from behind', as in:
have the LEDs on the inside of the (tube/sphere) and the epoxy/GITD mixture on the 'outside' ****

I have tried charging GITD epoxy mix from behind and the light does not transmitt to well thru the medium. I believe if a UV/LED was surrounded with say, with .250" to .350 " of glow material it might just do the trick. Now we need a good driver circuit to efficiencly light the UV/LED. Any ideas??

Check out this link:
http://www.glowinc.com/

COMMANDR said:

I believe if a UV/LED was surrounded with say, with .250" to .350 " of glow material it might just do the trick.

Click to expand...

Yes, this works better when the material is fairly thin (perhaps even thinner than you suggest). The glow powder crystals tend to render the epoxy opaque.

http://focus.ti.com/docs/prod/folders/print/tps61020.html

Looks like a nifty chip to build a supply around.

and all else we need is a timer circuit that turns the LED on for a few minutes, then off for a ~hour.

Alternately a 3-4v lithium battery of some kind and a dual-timer IC could be
configured so that one runs for a few minutes and the other for just under an hour.
(they trigger each other on/off)

I'm not shure that running a alkaline battery in this setup would be all that great.

The requirements of a boost circuit would also need it to 'sleep' in a very low power mode...
(but the timer has to then run from 1.5v for a while..? possible perhaps, but I know nothing about really low power circuits)

Also lithiums are just better for long term low power usage in general.

The runtimes are generally unbelievable (I really gotta check the calculations-- they are just thrown together guesses) but:

A 700mah 3.7 Volt Li-ION battery could last MORE than a month including losses.

What I would like to figure out is; how much light would this setup generate:
More than a 'Standard' wax candle or less ?

anyone have some glow powder and a UV led handy?

Brilliant!!!


Could you add a small solar cell to the top of the thing? The type that works under artificial lighting?

Then you could recharge a small capacity rechargeable cell which would power the UV LED at timed intervals to charge the glow material. This would give the advantages of luminescence while still allowing for all-night runtime.

Set it in bright light by day, and it runs automatically at night.



Brilliant!!!

This might be a good starter host. Coat the insides of the plastic tubes with glow powder, etc.

Actually I'm wondering IF that optical plastic will pass UV light.
(I had thought of this already with a long tube of optical plastic with glow powder on the outside-- it would give out a more even light I suppose.)

My current idea was to actually have a GITD sphere at the top, and a charger base station that connects to a 12V source (solar, wind, AC/DC).

But sticking a Solar cell on the top and putting the sphere on the bottom would be workable as well. A hook could be place above the solar for outdoor/inside hanging as well.

A Li-Ion + micro-controller should be a good combo. With a proper uC programming, you can have variable frequency(enabling you to adjust the timing for optimal glow or minimal glow) for the UV LED and still have very minimal battery usage since the uC will be spending most of its time in sleep mode.

Check these out:

http://www.kriana.com/

http://www.thinkgeek.com/gadgets/lights/6536/


BB62

BB62 said:

Check these out:

http://www.kriana.com/

http://www.thinkgeek.com/gadgets/lights/6536/


BB62

Click to expand...

Indeed my idea is nothing 'new'. Its implimentation however is novel.

Think of it simply as a UV LED powered GITD device. It's flourescent even without power, as long as there is a source of light to keep the phosphorescent 'charged'. So even if you forget to charge up the battery, it can still work. With a solar panel and automatic shutoff its virtually fool proof. (until someone invents a better fool )

Melchior said:

Indeed my idea is nothing 'new'. Its implimentation however is novel...

Click to expand...

Please understand that I was not capping on you - I just thought that what you described sounded familiar, and wondered if you could take off on what already existed.

What is GITD?


BB62

theamazingrando said:

TI had not considered the UV angle--The GITD material would take in UV light and output a different wavelength--is there an effiency advantage to that??

Click to expand...

I don't know about the efficiency but I think the effect could be nice -- no distracting flash of different-colored light, just a power-up of the GITD glow...