Re: foot pedal power
Given that it's making 60-80W of power it's safe to assume if it's 70% efficient you're talking about needing 100W of actual energy. 60-80 W is the max that unit can put out. An XO can't use that much power. I have the green wall-wart for an XO-1 plugged into a meter. It only reads power with a resolution of 1 watt. The most I've seen is 19 watts. With the CPU idle (not sleeping), backlight on, and battery charged, it takes 7 watts. If the CPU and memory are working, it takes 9 watts. 10-20 watts seems within reason to me. Small kids might have trouble putting out that much power for extended periods of time. For calibration, world class athletes (human powered aircraft) can put out 750 watts (1 horsepower) for an hour. Big muscles can put out more power than small ones: legs are better than arms. Using the thigh would probably work better than the calf but may not be as convenient. If anybody does the experiment, especially if you test kids, please let me/us know the results. Google for bicycle powered TV gets lots of info. Here is a good start: http://scienceshareware.com/bicycle-generator-faq.htm -- If a foot powered charger is going to be really useful for an XO, I think it will need some feedback mechanism so you can tell if you are pushing hard enough but not so hard that you are wasting effort. Force feedback and/or sound would probably do it. Maybe a LED. -- These are my opinions, not necessarily my employer's. I hate spam. ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
Mike Dawson wrote: Hi All, Such a device would need adaptation for the OLPC to be possible for kids (particularly those in the developing world) to use. We found by experimentation with weights that kids 8-12 average max sustained power applied against gravity was around 11W. They would need at This seems a bit pessimistic. Say 25Kg, 11W will raise 25Kg about 4cm in one second. Or about one step of a normal stair per 2 seconds. When was the last time you saw a kid go up stairs that slow? I have a scribble-blueprint of my ideal phone charger, but it's complex. Imagine a box ~100*25*80mm about 300g or so. This then unfolds into a device like a car footpump - an A frame. http://www.argos.co.uk/static/Product/partNumber/7402436.htm You step on this, and it generates a pulse of 100W or so. This is stored in a couple of LiFePO4 cells, which can take about 30W of charge each. It charges enough to recharge a phone in perhaps 100-200 steps. The gearbox and frame is challenging - it requires a light robust gearbox capable of perhaps withstanding impacts of 200Kg, and normal cyclic use of 120Kg or so. The electrical design is similarly complex, you need a peak power tracker to efficiently charge the battery from the variable speed, as well as smarts to optimise the speed profile for ergonomics. Then you need to use it as a motor to pop the pedal back up. (this is lighter than a spring.) This can be made a lot easier to make if you allow the weight to grow to a kilo or two, and drop the required efficiency. This also makes it a whole lot less usable. ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
On Sun, Jan 23, 2011 at 12:19:06AM +0400, Mike Dawson wrote: Such a device would need adaptation for the OLPC to be possible for kids (particularly those in the developing world) to use. We found by experimentation with weights that kids 8-12 average max sustained power applied against gravity was around 11W. Seems low. But there's hope with neuroplastic changes which would gradually increase power output if reward is sufficiently rapid. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
Hi All, Such a device would need adaptation for the OLPC to be possible for kids (particularly those in the developing world) to use. We found by experimentation with weights that kids 8-12 average max sustained power applied against gravity was around 11W. They would need at least +50-80% of what this thing actually generates to account for energy lost to heat / noise etc. That would be fine for a New York office worker who bikes to/from work, but not kids out here. The principle though is really exactly what I had in mind when I get around to making the next prototype out here... Given that it's making 60-80W of power it's safe to assume if it's 70% efficient you're talking about needing 100W of actual energy. Given a 10kg weight (pretty heavy) Work = Force x Distance 100W = (9.81 x 10) x 1m You would have to move a load of 10Kg up a meter every second. You could test this by taking some old style scales and putting a weight on one and then using your foot on the other side to make it go up and down and counting the number of times it goes up and down in a given time. Regards, -Mike On Thu, Jan 20, 2011 at 7:30 PM, Rafael Enrique Ortiz Guerrero raf...@sugarlabs.org wrote: Talking about human power.. potenco version2. http://www.potenco.com/products/pcg2/ Rafael Ortiz On Wed, Jan 19, 2011 at 9:44 PM, James Cameron qu...@laptop.org wrote: On Thu, Jan 20, 2011 at 10:38:59AM +0800, Carlos Nazareno wrote: I can add it to the wiki, but where should I add it? It's a Wiki, add it where you think best. Others may move it or link to it. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
Talking about human power.. potenco version2. http://www.potenco.com/products/pcg2/ Rafael Ortiz On Wed, Jan 19, 2011 at 9:44 PM, James Cameron qu...@laptop.org wrote: On Thu, Jan 20, 2011 at 10:38:59AM +0800, Carlos Nazareno wrote: I can add it to the wiki, but where should I add it? It's a Wiki, add it where you think best. Others may move it or link to it. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
Hey Wad, re: human power, there's at least one company that makes the mobile foot pedal charger already, and is marketing it to laptop and cellphone users. On 1/19/11, Martin Langhoff martin.langh...@gmail.com wrote: Do you have a google? Apply to wiki.laptop.org for best results :-) m Here's one that's less bulky than the Freeplay Weza that's already on the wiki. http://www.easy-energy.biz/products/yogen-max/ http://liliputing.com/2009/09/yogen-max-providing-pedal-power-for-your-laptop.html I can add it to the wiki, but where should I add it? Here ? http://wiki.laptop.org/go/Battery_and_power http://wiki.laptop.org/go/Peripherals#Power Should it have its own page like the Weza? Would it be better to make a new page cataloguing known foot pedal solutions out there? Thanks! Naz -- carlos nazareno http://twitter.com/object404 http://www.object404.com -- core team member phlashers: philippine flash actionscripters http://www.phlashers.com -- poverty is violence ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
On Thu, Jan 20, 2011 at 10:38:59AM +0800, Carlos Nazareno wrote: I can add it to the wiki, but where should I add it? It's a Wiki, add it where you think best. Others may move it or link to it. -- James Cameron http://quozl.linux.org.au/ ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
Re: foot pedal power
Hi On Wed, Jan 19, 2011 at 9:38 PM, Carlos Nazareno object...@gmail.comwrote: Hey Wad, re: human power, there's at least one company that makes the mobile foot pedal charger already, and is marketing it to laptop and cellphone users. On 1/19/11, Martin Langhoff martin.langh...@gmail.com wrote: Do you have a google? Apply to wiki.laptop.org for best results :-) m Here's one that's less bulky than the Freeplay Weza that's already on the wiki. http://www.easy-energy.biz/products/yogen-max/ http://liliputing.com/2009/09/yogen-max-providing-pedal-power-for-your-laptop.html I can add it to the wiki, but where should I add it? Here ? http://wiki.laptop.org/go/Battery_and_power http://wiki.laptop.org/go/Peripherals#Power Peripherals#Power seems the natural place. Should it have its own page like the Weza? Sure. Would it be better to make a new page cataloguing known foot pedal solutions out there? If you have time You can make a hierarchy wiki page like /Peripherals#Power/FootPedal Thanks! Naz -- carlos nazareno http://twitter.com/object404 http://www.object404.com -- core team member phlashers: philippine flash actionscripters http://www.phlashers.com -- poverty is violence ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel ___ Devel mailing list Devel@lists.laptop.org http://lists.laptop.org/listinfo/devel
