I bought this kit from Ghurd. He now sells them from his site at
http://ghurd.info. It was inexpensive, a well thought out design and I had a lot of fun building it.
I wanted to try and build a micro power installation which could power a light, or a laptop, or a small stereo, or two of the above. I had the stereo going last night with the small 7Ah battery (a $5 dump shop find with a switch and small halogen bulb). Roughly calculating from voltage it was at 12.64v so it only used up around 15% of it's capacity powering my 10w marantz amp for a few hours at moderate levels. I've thought about using sub c nicads or even the extravagance of using some a123 cells but they are too expensive. An SLA doesn't quite have the guts to power my small laptop directly properly as the backlight flickers, so I've yet to figure that one out. This is although I've worked out I can run the lappy on about 7w if I undervolt the cpu and have the brightness on lowest setting. It's a thinkpad X31. I've also got a couple of 12v power tool batteries I want to charge with this setup. I've got the bits for it just need to make the connectors for it. I've also been experimenting with high efficiency LED lighting. I made some for my camper (RV for US people) and I got real brightness from 6w of actual usage. Much bright than a fluoro of that wattage. So, that may be the next project after the power tool solar adapter :-)
I learnt alot from building this kit . I learned that on the power transistor that the order of the pins with the thing facing you are the gate, the drain and the source. It took awhile to figure that one out (even though it shows it is so on the instruction schematic). Otherwise, smooth sailing. It's not really a kit for absolute beginners though, mainly because it can be configured in so many different ways and because of such the instructions are to the point but could be a bit terse if you aren't used to that sort of thing. For the setup I have it on there is no dump load, only a Schottky diode and the power transistor. It shorts out the panel when the specified voltage comes up on the battery. The panel I have only puts out a maximum 1.4A so that's the reason it doesn't need a dump load and I'm not worried about saving that excess energy.
As others who have built this kit have said, it's really satisfying to see the dump light go on and then flash as the battery is supplied and then kept at the right voltage.
Because the kit is so miniature I tried to get it all to fit in a box as small as possible. A real bonus was that it worked first time which was great because by the time I got it all in the box if I needed to troubleshoot I wouldn't have been able to without much swearing, calling-of-names and gnashing-of-teeth.
Overall, I think this is the best thing I've ever made and really happy with the outcome. Thanks so much Ghurd. If you want to use these photos on your site, let me know and I'll send you some bigger versions than the ones here.
