Few weeks ago, my mother got a couple of new yard lamps. LED, super bright, and they run just about all night. It might have been this guy:

http://www.hardwareandtools.com/invt/5103551?ref=gbase

If not, pretty much identical. Walmart and HOme Depot both have them for $20.

My thought is... the solar panel and battery charger are on the pallet above the lamp. It looks easy enough to pull that off and use it stand alone, maybe epoxy a MALICE clip to the back to attach it to packs. Then leave terminals where the wires are, so I can clip leads to the lamp if I chose to use it at night. It runs on four ni-cad AAs. I'm thinking should be easy enough to isolate the day/night sensor, and maybe add a switch if I really want one. Or turn the whole thing into a strobe with the addition of something the size of a AA (cap, maybe a couple of resistors) that you can choose to add. Or just a multi position switch....

But the lamp itself isn't very big. Another clip would let you mount it over the shoulder (ala Aliens) or to a bike or to almost any surface. And I'm pretty sure if you had to, the lamp and charger would survive being powered with some alkalines. It is already water proof, and it is LIGHT for what it is, less than a pound. Of course, with this on clip leads, the charger can be a stand alone item.

Never seen a circuit diagram for one of these things. Does anyone have a clue what kind of sensor they are using? Any surprises I should be wondering about?

Am I crazy, or just crazy enough for this to work?

I say have at it and report back what you find! Backpackable solar power would have a lot of uses. There's plenty of systems already available, but when you build it yourself you get a lot more options.

-Blast

Hi Ironraven,

The circuit will probably be a really simple one such as shown below, using an Light Dependant Resistor (LDR), a single transistor or darlington, a few resistors (the 470 ohm resistor and LED is replaced with something like a 3 x 47 ohm resistors and 3 LEDs), a variable preset resistor (to set the light value to switch on the LEDs) and the LEDs (shows a single LED in the circuit). The voltage from the NiMh or NiCd cells will probably be unregulated. I would assume about 3.6 v (+Vs) as the garden lamp has 3 NiMh cells stacked in series. The Solar Cell will most likely be something like a 4-4.5 Volt 120-140mA Solar Cell (depending on the solar cell Area) such as here at http://www.dealextreme.com/details.dx/sku.12391 with a reverse blocking diode at around 0.6V to give the 3.6-4.0V for the NiMh cells. Total Solar power will be around 0.45 Watts assumming the solar cell is this large 8cm by 8cm (the one on the garden light looks to be a lot smaller possibly half the power). The NiMh cells are most likely to be generic 1.2v 600 mAHr AAA cells. Charge time for the cells will be around 6 to 8 hrs in bright sunlight (double this for the smaller solar cell on the garden light).




The LEDs will have a typical power output around 60 mW each giving a total of 180 mW output. Total power for the circuit would be around 0.4 - 0.5 Watts giving roughly about 4-6 hrs lighting use. Efficiency is poor for this type of circuit but the component costs are very small.

Deal Extreme has lots of different Solar Cell Chargers such as this one at http://www.dealextreme.com/details.dx/sku.4813 being much more flexible in use. With this device you could connect one of these USB LED lights http://www.dealextreme.com/details.dx/sku.5452 and still power another USB device such a MP3 player or Cell Phone at the same time.

For less than $20 even something like this at http://www.dealextreme.com/details.dx/sku.9134 will produce more solar power. A video is also available showing the solar charger here at http://www.youtube.com/watch?v=sl7lgFhNTs8

Hope this helps.

I've used solar-powered yard lights at Burning Man for years, and they are not the most robust items I've seen. I don't know about the ones you are considering, but the ones I have don't last more then a few years (out for one week on the playa, so that's a few weeks' use).

Here are photos of one I took apart:
http://civex.smugmug.com/gallery/5099462_pLNsB

Two AA batteries, one LED, a circuit board, and the solar panel. Yours will vary, but it shouldn't be too difficult to dismantle then re-assemble more or less as you wish. I would give it a good testing period before relying on it. It's water proof now, it stays on all night now, etc. Burning Man is a harsh environment, so I may be too hard on them, but I would be interested in seeing how long the units stay working at the claimed specs.

This is a really good link describing garden solar light electronics;

http://www.talkingelectronics.com/projects/SolarLight/SolarLight.html

The electronics may be slightly more sophisticated than originally thought.

About 2 years ago, in October, we had an earthquake and lost power state wide. My co-worker's father took several of these LED yard lamps and removed the bottom halves off. He then brought them into the house to light up the kitchen and living room. It was a great idea.

Ironraven, I you should try experimenting and let us know.

http://www.reuk.co.uk/Solar-Battery-Charging.htm

DIY solar battery charger

http://www.instructables.com/id/Solar-Battery-Charging/

http://www.instructables.com/id/Rain-or-Shine-Solar-Charger/

http://www.instructables.com/id/Universal-Solar-Charger/

whole bunch of solar projects there

Why use a diagram which uses the European symbol for resistor rather then the American symbol for resistor? Wouldn't more people recognize the American standard?

Jeanette Isabelle

I like the idea of using solar yard lights as a component in my home based E-kit ... but with a switchable light ...so I could turn it off if desired.
Though it would be nice if they were robust enough to get bumped around a bit and definitley long lasting enough for the whole night ....so I could use them for outside security etc. ONce the big quale hits here in Cali ... power might be out more than one night.
Great link to the dealextreme website for that pocket solar charger ... that might prove real handy to have around !
Thanks for feeding my gadget habit !
And of course, it looks like it might be better to fab up my own for a more portable and compact setup for for mobile bugging out....or just camping out in general.

Bah, buying it is less fun. And this gives me a work lamp of reasonable impressiveness that I can clip to it. :P

And thanks for the schematics, I hadn't found anything on what they were using for a sensor.