So far everyone seems to like both the subject and implementation.
There was a companion article published in EDN (Dec1,2011 'A Diode Ladder Multiplies...') related to this application. EDN is a Design News sister publication, It was developed as part of this project but I opted for the implementation finally seen here, which provides a more incremental and potentially useful solution set. I also believed it would be easier to describe and create the analysis included in the article.
The article includes a power load analysis and some information about battery rating characteristics. I would still look forward to hearing comments about how the simple charger, shown in the schematic or what and how those other losses, only mentioned in the article, effect the application.
The project worked out pretty good and the final assembly has my 'cool' factor stamp of approval. The author can be reached at email@example.com
The concept is good, and there is always room for another version of this type of equipment. The challenge being that the solar cell will only produce a given number of volt-amps, So it is not something-for-nothing. There is also the overhaed for the converter. So there is indeed a tradeoff. Increasing the intercepted power requires more solar cells, which do indeed cost more, and take up more room.
Presently most solar cell installations need to have a voltage changer someplace in the system, which validates this as a good idea.
While it is technically possible to place enough solar cells in series to gain a voltage high enough to operate electronics and charge batteries, but I know of a company who studied the solutions for solar-charging cell phone and they came to the conclusion that using a *single* cell (which delivers around 0.45V at optimal irradiation and loading) and upconverting this to the battery voltage was more efficient and a better solution than using a series of cells. It may have been because of variation in quality and the shadowing which causes a string to fail to deliver as soon as a shadow is present on one cell... So, they designed an up-converter from 0.45V to battery level (typical Li-Ion around 4V).
Apreher, you are right. I think the system can expand further for different applications even for home automation. Since itís a self powered device using Solar panel, we can call itís as a green device or ecco friendly device.
I agree, Al. It's very creative. The author also did this for relatively low cost. The most expensive item on the BOM is the Prioto board at $13.55. Given the kinds of apps that this is targeted for, the costs are tolerable.
apresher, I think you are correct. There are a lot of possibilities in the home for this kind of thing.
What I like most is the line about taking the products apart and adding components. My sons and I do this a lot with computers, of course. We are just getting in to other types of devices.
I once worked at a large aerospace contractor where there was a senior engineer who took things apart all the time to see how they worked. He needed little prompting. He also could get away with it becuase of his standing with the company. So, if we wanted something taken apar that was expensive (and probably wouldn't go back together again) we woulld put it on his desk when he was out. We would also take off all the stickers that said do not disassemble. He would always take it apart. It was great!
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