Self-recharging GITD Fob

[JimmyM]

Wasn't really sure where to post this, but it involved LEDs so I figured here is better than anywhere else.
Glow in the Dark powder, etc basically stores light and releases it slowly over time. GITD stuff recharges really well from UV light sources. So, what if you potted a long delay, ultra low current timer with a UV LED or 2, in GITD epoxy? A couple of Lithium button cells should operate for months, turning on the UV LED for 10 seconds every 2,4,6 or whatever hours. Continuous Glow. Yeah, I know, Tritium does this, but you have to admit, it's a neat idea.

Thoughts?

 

[Tekno_Cowboy]

Seems like an interesting idea. Keep us posted. :thumbsup:

 

[JimmyM]

Just a thought. I have some timers, etc lying around, Maybe I'll toss together something on the breadboard. I've been looking for a reason to test out the logging functionality of my Fluke 189.

 

[Burgess]

Continuous Glow.
Yeah, I know, Tritium does this,
but you have to admit, it's a neat idea.

Yes, indeed, that certainly IS a neat idea !


:twothumbs


_

 

[Kilovolt]

A very nice idea IMO.

 

[Snow]

Sounds like a cool idea to me. Tritium is cool, but not as bright as some of the most effective glow powder.

 

[bansuri]

Cool idea! There may be fewer "fundamental" inventions left out there but the unexpected convergence of existing technologies is where the money is at. I'm sure there's a large market for such a device, especially if marketed at the <$10~$15, impulse item in the checkout lane.

Thinking a little farther out:
Light sensor to prevent it from charging when it's light out.
Low battery flash.
If mass produced enough to get the price right it would be a great item to have corporate logos on for employee gifts.

 

[MegaTesla]

Nice idea!

My dad bought a cheap 1 watt LED flashlight a few years ago that has a blinking LED under the clear tailcap. I'm going to open it up to see how it works and if it is possible to put a UV led in there with GITD tailcap...

 

[JimmyM]

Hey, guys. I hadn't thought about "mass marketing" or anything like that. But nice to know you're thinking.

MegaTesla. There are LEDs that have the "blinker" built right in.

I was looking at the picoPower Atmel chips last night thinking "why would I possibly need a microcontroller for this". Now I have my answer. Low battery warnings and light sensors.
What would the low battery warning be? It already flashes. Also, reading the battery voltage takes more power.

However, using a microcontroller to enable these features would consume more power. So in an affort not to have it not flash during the day, you kill the battery faster.
I have a simple LM3909 red LED flasher sitting on the top of my bench. It's been flashing since 1/1/2000 on a Duracel D cell.
Ultra long time delays are a pain when you want to just use uA or nA. But shorter delays are easy and can just turn the UV led on for a shorter time. Easily run on 3 x 1.5V cells, or 2 Lithium cells. The Lithium cells are larger in diameter than the little LR44 1.5V alkaline/Silver cells.

 

[strinq]

Seems like a great idea.
Better patent it quick.


Hmmm, am thinking now about a built in function like that for flashlights. A low power bulb right beneath wherever the GITD source would be following ur concept of glowing faintly every few hours.

 

[DM51]

This is an ingenious idea. Does GITD re-charge in as little as 10 secs, and how long does a "charge" last? Presumably you could adjust the timing to whatever works best. The low-light sensor to trigger charging is a clever idea too.

 

[qtaco]

Maybe I'm missing the point, but wouldn't it make more sense to just run an led in the visible at low power? Because you'll lose energy powering the blinking circuit, and more significantly, you're going to lose a bunch of energy when the GITD stuff captures and converts the UV light to chemical energy.

 

[xenonk]

The laws of thermodynamics make for a rather large monkey wrench.

The effect would probably look cool, though.

 

[JimmyM]

Glow powders recharge best with light in the UV range.
See this article at Glow Inc.

I'm not suggesting this is breaking any thermodynamics laws. It would just keep the Glow stuff glowing better overnight or for extended periods of darkness.
Powering the UV LED constantly would deliver more brightness, sure, but a flasher circuit would extend the battery's life by many many many times. At the expense of average brightness. A simple circuit can draw only 1-100 uA of current while the LED is off. When the LED is on, it will use about 20,000 uA (20mA).
I'll see about building a "simulator" to flash a UV LED at some GITD object in a black box. I'll rig some sort of light sensor that I can record with my Fluke 189.
I dunno. I just figured it would be a neat exercise.

 

[HKJ]

Powering the UV LED constantly would deliver more brightness, sure, but a flasher circuit would extend the battery's life by many many many times. At the expense of average brightness. A simple circuit can draw only 1-100 uA of current while the LED is off. When the LED is on, it will use about 20,000 uA (20mA).

Why not run the UV led at 100uA all the time? Or just use an ordinary led at 100uA without any GITD power?

 

[JimmyM]

Why not run the UV led at 100uA all the time? Or just use an ordinary led at 100uA without any GITD power?

I'd have to see about an LED that could work down at 0.1 mA.

 

[Search]

I just bought some GITD O-rings from Sigman.

Exactly how long should I expect them to glow? I've never heard.

 

[HKJ]

I'd have to see about an LED that could work down at 0.1 mA.

Small leds has no problem working at 100uA, some of the most sensitive leds will light up, just by touching the wires, but I have not checked their efficiency.

 

[Mike V]

I've always wondered why some flashlights don't come with very small LEDs to simulate Trits?

Like those flashlights you see in the cabin or aeroplanes that have a little red flashing LED to find them in the dark.

I'd like a small green constant on LED or something on the tail.

Would use almost no power.

 

[Creecher]

I think it's a great idea. My only concern would be the penetration of the UV from within. A block of GID epoxy really only glows on the outside and is fairly dim in the middle when split apart.

I'm definitely interested to see what happens with this one.