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Micro-Solar LED Desk Lamp | 40 comments (40 topical, 0 editorial)

Re: Micro-Solar LED Desk Lamp (3.00 / 0) (#17)
by ghurd on Fri Feb 8th, 2008 at 07:56:32 AM MST
(User Info)

Guys,

Everything needed is already here in more quantity than I care to admit. Except for one of Claude's fancy circuits.

A better plan for the use of power would make the numbers look better.

About 5X the money would get 15X the power.

Catch 22. There would be a LOT more power available in the summer, when the lamp isn't needed as much.

Anglepoise and CFL. I put rubber bands with the lamp springs.

LEDs on less than a 12V system is a complete waste of solar cells and power.
I need this lamp to be working when I need it. Draining a couple AAs and trying to see with 80% dead cells isn't going to do me any good.
Besides, there are more than enough nicds here to build a 12V 50AH pack.

The lamp will be a story by itself. If the lamp is on, and the battery is below 12.22V, then a tiny 12V transformer gets grid power to help supply some of the lamp power. It won't charge the battery because it doesn't quite make enough ma to power the bulb, but it will keep the battery from getting too low or me from being in the dark.
It will be able to use every drop of available RE.

Geoff must live on the moon!
G-

Re: Micro-Solar LED Desk Lamp (3.00 / 0) (#18)
by claude on Fri Feb 8th, 2008 at 11:10:05 AM MST
(User Info)

G, you really got me thinking about THE LAMP.

Truth is I still have none to light up my desk. I rely for now on my good old 22" CRT monitor to make my keyboard visible. But The Idea of having my own LED lamp!

You are right, a 9V driver is a waste of power. But 12V out from a 11.8V battery isn't easy. One would need a Buck-boost converter to overcome this. And here's how a simple lamp becomes rocket science.

Claude

[ Parent ]

Re: Micro-Solar LED Desk Lamp (3.00 / 0) (#19)
by ghurd on Fri Feb 8th, 2008 at 11:23:43 AM MST
(User Info)

The 9V driver is fine. I was talking about solar charging 3 AAs for an LED.

I only need about 9.1V for "full brightness".
That's 96 chips at about 4.5ma each. Pretty efficient. :-)

I don't want to run the battery lower than about 12.2V anyway, hence the grid-assist.

Maybe someday you will have Enough LEDs to build that lamp without so much worry?
Build the lamp already!

Me + Buck + Boost = Smoke
G-

[ Parent ]

Re: Micro-Solar LED Desk Lamp (3.00 / 0) (#20)
by Bruce S (bruce(dot)stahl <at>gmail (dot)(com)) on Fri Feb 8th, 2008 at 11:42:10 AM MST
(User Info)

Now I'm getting real curious about how much area you are looking to light up.
Work area ? desk top ? or whole room?

The newer Lexon II , III and K2 have some impressive lumens now. They're still within the 3.3Vdc range and even the newest one will hold a steady 3.6V 350ma with bliding light output. With I'd say, a 20 degree beam, that green one I took a picture of will put a light on my ceiling 12 feet up and when using a defusser will cast a nice glow on my office.
Digital camera seems to have problems with some of the different light colors but I can certainly try taking more if you wish.

50Ah of NiCd? that's it, do I need to ship more;_)?

I agree with the fact that the bigger, or more intergrated, you put on the RE the better the numbers look, but what fun is that?

Are you looking to use a dump controller in reverse to keep the LEDs lit?

Cheers
Bruce S

[ Parent ]

Micro-Solar LED Desk Lamp | 40 comments (40 topical, 0 editorial)

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