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Calculators

Highly capable solar-powered calculators
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Have you noticed that the fanciest calculators you can buy all take batteries? One reason is that they are programmable, and most people want the things to remember their programs, rather than typing them in every time you want to use them. Yet nothing is as convenient for the long term as a solar-powered calculator. Surely if one had a flip-top lid, enough solar cells could fit inside the lid to power the calculator in most light. All that is needed is an appropriate storage device, and Hewlett Packard had one many years ago, and it hasn't been seen since. I think it was the HP67, that had a little motor and you fed these small magnetic strips through it, and your programs would be saved on the strips, for loading later on. Cool. More sophisticated tricks using "flash" memory could instead be used these days. Well, I want such a calculator; when will it be available???
Vernon, Jul 01 2000

(?) solar powered laptop chargers http://www.jademoun....com/laptopchg.html
For when even the spiffiest calculator won't do... [egnor, Jul 01 2000, last modified Oct 21 2004]

Slashdot discussion http://science.slas...mode=thread&tid=126
They are still under development. Maybe they just don't have enough research $ to finish. [Vernon]

Background info http://www.luminet....nah/new/nsolcel.htm
There are those who claim we still don't have the technology to do this, but I think all it takes is $$$. [Vernon, Oct 04 2004, last modified Oct 21 2004]

(?) Background info http://www.luminet....nah/new/nsolcel.htm
There are those who claim we still don't have the technology to do this, but I think all it takes is $$$. [Vernon, Oct 04 2004]

[link]






       I don't see why you need batteries to retain information, for example that little memory card on my play station has no batterys that I know of. Well if you made this calculator with a RAM and a memory chip that was interchangable you could share progams with your buddies.
mika_ranta, Jul 01 2000
  

       I'm pretty sure that the memory sticks you are talking about ARE 'flash' memory, as already described.
Vernon, Jul 02 2000
  

       Programmability has nothing to do with it. Even dinky little four-function solar calculators have a "memory" cell! Flash memory and other nonvolatile memory technologies aren't exactly "sophisticated tricks" (though flash memory does take quite a bit of power to write).   

       More sophisticated CPUs and bigger, higher-density displays require more energy, and solar cells under indoor lighting don't provide very much power.   

       Forget calculators; if you could make it work, the real market would be solar PDAs.   

       The real limit to the development of gadgets is energy density -- the amount of energy you can store per unit of mass or volume. It's easy to design a super-spiffy PDA/calculator/cellphone/whatever that has wireless RF and GPS and a super-hi-resolution display and a super-fast CPU and lots of RAM... and eats a poor little AA battery in three seconds flat. It's all about reducing power consumption (e.g. Transmeta) and increasing power supply (e.g. zinc-air batteries and fuel cells).   

       Maybe if we work on the consumption side long enough, solar cells will become practical, but we're a long long way from being there, and people demand ever-increasing functionality. HP isn't gonna make "the fanciest calculator you can buy" something lame just so it can run on solar cells.
egnor, Jul 02 2000, last modified Jul 05 2000
  

       I have here in plain view as I type this a Texas Instruments TI-36X solar powered calculator. It is about the most capable purely-solar calculator that I have been able to find. It seems to have just about everything EXCEPT programmability, and a large LCD display for graphing. Please note that the physical dimensions of the upper surface (containing solar cells, LCD, and keys), is about 2&3/4" by 5&1/2". The actual solar cell panel is only 2" by 3/8". Now if you would doublecheck my original post, you might notice I said somthing about covering a fliptop lid with solar cells. Now this calculator does fractions, and I just now used it to find out that the overall upper area is 20&1/6 times the area of the existing solar panel. So a fliptop lid should produce 20+ times the power of the existing panel. I am certain that this would be enough for a programmable calculator, especially since the existing panel works fine under moderate-light-level conditions. Furthermore, by incorporating standard-camera-flash electronics and suitable capacitor, running a motor to save programs on a magnetic strip is also quite feasible. As you say, a solar PDA would be a more popular choice than a solar super-calculator, but the current technology will allow the calculator, so that is all I am wanting at this time.
Vernon, Jul 03 2000
  

       You are wrong.   

       In this field (gadget design), at least, "energy density" almost always refers to one of gravimetric energy density (watt hours / kg) or volumetric energy density (watt hours / liter).   

       It's the only meaningful way to compare battery technologies. Solar cells are a different matter, and perhaps I should have used a more generic term like "power supply" instead.
egnor, Jul 05 2000
  

       Allow me to direct your attention to the website www.uspto.gov, which is the U.S. Patent and Trademark Office. Proceed to inspect Patent #4,445,050, granted in April of 1984. This patent was rather ahead of its time, and will expire next year. It concerns a NON-photoelectric effect solar cell. You may recall various experiments by the Department of Energy, having to do with converting power to microwaves, transmitting the microwaves, and receiving them and converting them back to power. Total efficiency of wireless power transmission was, if I recall correctly, better than 80%. The main gadget that was responsible is something known as a "rectenna array", which is an array of antennas combined with rectifiers. The inventor of the patent proposed that microscopic rectenna arrays be tuned to absorb visible-light photons, and not merely microwave photons. Now I don't know if all the solar-cell manufacturers have forgotton about this patent, or are merely waiting for it to expire. Certainly we did not have the ability to mass-produce the things in 1984. TODAY is a different story. If we are using deep ultraviolet to draw circuit patterns today, then those patterns can be arranged as visible-light-absorbing antennas, and rectifiers. 70% conversion of light into electricity is not unreasonable! Which means the solar panels described for a calculator, or a PDA, or a laptop charger, or whatever, will be more powerful than ever (most solar cells sold today are cooking if they do 15% conversion).
Vernon, Jul 06 2000
  

       Has anyone heard anything about any silicon company starting to make those "rectenna" solar cells yet?
Vernon, Mar 10 2002
  

       Well, a couple more years have gone by, and the question I asked before still needs answering. Some part of that answer may be found in the Slashdot link.   

       (EDIT)No, I take that back; the Web page linked-to at one of the Slashdot replies is no longer there. But I found another (and put link here).
Vernon, Apr 30 2004
  

       Re. calculators with little magnetic strips. I remember those from high school = nerd accessory. Predated even (commercial) PCs, as I recall (eg. the Vic 20, C64).
Elmer Phd, Jun 15 2004
  

       HP65
bristolz, Jun 15 2004
  

       You folks are referencing old battery-powered calculators. I want a solar-powered job that is as capable as the most modern battery-guzzlers. ALL it should take are bigger and/or more-efficient solar cells. (And as mentioned in the main text, some sort of data-storage is of course necessary to deal with night.) When are we likely to see such a thing? Any ideas?
Vernon, Jun 15 2004
  

       Would a wind-up version do instead?
david_scothern, Jun 15 2004
  
      
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