HP Forum Archive 19

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Why No Solar Calculators? Message #1 Posted by Jeff on 30 Aug 2010, 6:11 p.m. My Casio G-Shock is solar-powered. I have a Casio 4-function solar calculator. Why can't HP go solar? Aesthetics? Power limitations? I like solar because the batteries tend to last a long, long time.

Re: Why No Solar Calculators? Message #2 Posted by Lyuka on 30 Aug 2010, 8:09 p.m., in response to message #1 by Jeff HP easy calc 100, office calc 100, office calc 300, 10S and SmartCalc 300s are all solar and battery powered.

Re: Why No Solar Calculators? Message #3 Posted by Katie Wasserman on 30 Aug 2010, 8:19 p.m., in response to message #2 by Lyuka ... and the 6S solar. I like this one a lot. I found a ton on a liquidation site for next to nothing and put them in geocaches.

Re: Why No Solar Calculators? Message #4 Posted by Tim Wessman on 30 Aug 2010, 9:15 p.m., in response to message #1 by Jeff Anything but the simplest chip won't have enough power to run with solar. The ARM7 in the 20/30 and 12c spike too high to be fed with solar. I would like to see someone power a 50g with solar though. Would be interesting to see exactly how big of a panel it would need. . . TW

Re: Why No Solar Calculators? Message #5 Posted by Maximilian Hohmann on 31 Aug 2010, 5:14 a.m., in response to message #4 by Tim Wessman Hello! Quote: Would be interesting to see exactly how big of a panel it would need. . . How many hours a day do people actually use their calculator? And how many hours a day are the lighting conditions sufficient to charge a battery? So even a small solar panel can be totally sufficient to provide enough electricity for a calculator. Even for one with a powerful processor. Regards, max

Re: Why No Solar Calculators? Message #6 Posted by DaveJ on 31 Aug 2010, 6:00 a.m., in response to message #5 by Maximilian Hohmann Quote: How many hours a day do people actually use their calculator? And how many hours a day are the lighting conditions sufficient to charge a battery? So even a small solar panel can be totally sufficient to provide enough electricity for a calculator. Even for one with a powerful processor. In theory, yes. In practice, no, not even close. If you do the math it just isn't practical. Factor in indoor fluoro light being orders of magnitude less capacity than sunlight. Factor in battery charging circuit efficiency at low power levels. Factor in that lights get turned off at night. Factor in calcs get left in draws etc. It simply isn't practical for all but the most flea power processors. You'd only have to have the thing run down on you and not be ready to use when you need it ONCE to realise who annoying and unreliable it would be to have a solar rechargeable calculator. You are infinitely better off having it simply battery powered. I've been there and done the calcs and the measurements. Dave.

35 years later Message #7 Posted by Frank Boehm (Germany) on 31 Aug 2010, 8:54 a.m., in response to message #6 by DaveJ Considering the first solar powered calculators have been sold 35 years ago, I wonder where the technological advancement got stuck. (OK, solar & battery tech has not advanced much further, but CPU tech certainly has...)

Re: 35 years later Message #8 Posted by DaveJ on 31 Aug 2010, 6:05 p.m., in response to message #7 by Frank Boehm (Germany) Quote: Considering the first solar powered calculators have been sold 35 years ago, I wonder where the technological advancement got stuck. (OK, solar & battery tech has not advanced much further, but CPU tech certainly has...) Not by a huge amount when it comes to this sort of stuff. Those ASIC's used in the solar calc from 20+ years ago were already very low voltage and had a quite high mips/MHz figures. Today's devices with all the improvements in solar and silicon manufacturing technology might only might give you say an order of magnitude increase at best. But even 10x the performance of the old solar scientific calc's ain't much to right home about. That's evidenced by the fact you can still only buy pretty basic scientifics as a solar calc. The 300S would maybe be an order of magnitude more powerful than the old scientifics for example, but it's got battery backup. Dave. Edited: 31 Aug 2010, 6:09 p.m.

Re: Why No Solar Calculators? Message #9 Posted by Crawl on 31 Aug 2010, 10:47 a.m., in response to message #4 by Tim Wessman Several years ago (maybe more like 10...) I saw some solar panels that were intended to power Game Boys. They were about 4 inches by 6 inches, as I recall. I know someone who used a 3"x3" solar panel to power an MP3 player (of course, that only had to replace a single battery, not four). The Game Boy thing was a commercial product; this was more of a hobbyist project. He had to use something like a 1F supercapacitor to get it to deliver continuous power.

Re: Why No Solar Calculators? Message #10 Posted by John B. Smitherman on 31 Aug 2010, 12:04 p.m., in response to message #9 by Crawl There are many usb chargers on the market. I like devices like this which provide flexibility for charging cell phones, iPods, etc. from a/c, auto d/c or solar sources. Link to usb charger I assume that something like this could be used to power the 50G. Does anyone have any experience with solar usb chargers? Regards, John

Re: Why No Solar Calculators? Message #11 Posted by Crawl on 31 Aug 2010, 1:02 p.m., in response to message #10 by John B. Smitherman That supposedly can put out 3W, and, if this is right, the HP50g uses about 0.6W at most -- it might be possible! (in bright, direct sunlight) Failing that, I do have a battery charger for AAA's that can use solar power, but I think the ratio of the time spent charging the batteries to the time they can be used in a calculator is rather large.

Re: Why No Solar Calculators? Message #12 Posted by DaveJ on 31 Aug 2010, 5:50 p.m., in response to message #11 by Crawl Quote: That supposedly can put out 3W, and, if this is right, the HP50g uses about 0.6W at most -- it might be possible! (in bright, direct sunlight) And there's the kicker, that would drop to an order of 10's of mW indoors. Who wants a solar calc that's only usable/charagable in direct sunlight? Dave. Edited: 31 Aug 2010, 5:59 p.m.

Re: Why No Solar Calculators? Message #13 Posted by DaveJ on 31 Aug 2010, 5:51 a.m., in response to message #1 by Jeff hope/http://www.eevblog.com/2009/12/04/eevblog-48-solar-power-hope/ Dave.

Re: Why No Solar Calculators? Message #14 Posted by Walter B on 31 Aug 2010, 6:34 a.m., in response to message #13 by DaveJ Very nice video :)

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