kyodai
Experienced Member
OK, I am not that deep into electronic circuits and stuff. I can replace a capacitor, repair some broken contacts, but i never designed any circuit from scratch.
So to make it short - my idea was to add a solar panel to one of my palmtop PCs. I think something like a tidalwave clone is a good candidate because their main power comes from 2 AA-batteries in a series circuit, so basically you need 3 Volt. I don't know how many ampere it consumes, but it probably depends on the program you run and the processor speed selected. Usually these have about 10 hours of battery life in normal use, so I'd rate the typical AA-battery (a good one) at 2000 mAh, so my guess is it draws around 200 mili Ampere in standard use, probably more at peak. Watt = Volts x Ampere (If my school time wasn't a total waste of time), so a 3 Volt 0.6 Watt Solar cell should be sufficient for normal use, might not be enough for "peak" power consumption.
Well so i looked around a bit for solar cells that could fit.
Radio Shack has some that seem quite the size i like. The lid of the Tidalwave is 4.5 inch x 9.7 inch (11.5 x 24.5 cm), so the solar cell should be roughly that size, preferably a little bit smaller.
The one i looked at is this:
http://www.amazon.com/RadioShack®-...1456004820&sr=8-30&keywords=radio+shack+solar
From the size i could fit 3 of them on the lid if i calculate correctly. 1 Watt peak power at 6 Volt each, that would be 3 Watt - well probably much less unless it's a very sunny and i point the lid directly into the sun. But i think 3 Watt already sounds like it would be sufficient.
OK they are 6 Volt (Well at peak i guess), so the goof in me says like "hey you need a resistor. Wanna reduce the volatge by 3 Volts and we assume the Palmtop could use up to 500 mili Ampere at peak (Not sure how realistic that is though), then we'd need a resistor that is 3V / 0.5 A = 6 Ohm
OK, now some of you are hopefully already laughing. Well I have a feeling that there might be a better way to reduce the volatge? Especially since the power the solar cell produces varies incredibly - i think on a cloudy day we would likely get only 1/10th of the theoretical 3 watt. I know there are things like step-down transformers so you can use a 120 Volt device on a 240 Volt poer socket. But for 6 volt to 3 volt?
I know, a good solution would be to use rechargable batteries, buy a 2 dollar solar cell charging circuit and be done, but hey, making it easy wouldn't be so much fun, right? So at first I'd really like to evaluate the possibility of running the device completely from a solar cell without a battery buffering it. How do these 2 dollar solar calculators do that without risking supplying too much voltage or power during peak times?
Imho the perfect solution would have a little switch so i can select if the solar panel charges the battery (Here comes our cheap charging circuit from china again) or directly powers the palmtop. The switch also makes sense when you use non-rechargable batteries since trying to recharge alkalines can lead to them blowing up, leaking or other nasty problems, right?
So to make it short - my idea was to add a solar panel to one of my palmtop PCs. I think something like a tidalwave clone is a good candidate because their main power comes from 2 AA-batteries in a series circuit, so basically you need 3 Volt. I don't know how many ampere it consumes, but it probably depends on the program you run and the processor speed selected. Usually these have about 10 hours of battery life in normal use, so I'd rate the typical AA-battery (a good one) at 2000 mAh, so my guess is it draws around 200 mili Ampere in standard use, probably more at peak. Watt = Volts x Ampere (If my school time wasn't a total waste of time), so a 3 Volt 0.6 Watt Solar cell should be sufficient for normal use, might not be enough for "peak" power consumption.
Well so i looked around a bit for solar cells that could fit.
Radio Shack has some that seem quite the size i like. The lid of the Tidalwave is 4.5 inch x 9.7 inch (11.5 x 24.5 cm), so the solar cell should be roughly that size, preferably a little bit smaller.
The one i looked at is this:
http://www.amazon.com/RadioShack®-...1456004820&sr=8-30&keywords=radio+shack+solar
From the size i could fit 3 of them on the lid if i calculate correctly. 1 Watt peak power at 6 Volt each, that would be 3 Watt - well probably much less unless it's a very sunny and i point the lid directly into the sun. But i think 3 Watt already sounds like it would be sufficient.
OK they are 6 Volt (Well at peak i guess), so the goof in me says like "hey you need a resistor. Wanna reduce the volatge by 3 Volts and we assume the Palmtop could use up to 500 mili Ampere at peak (Not sure how realistic that is though), then we'd need a resistor that is 3V / 0.5 A = 6 Ohm
OK, now some of you are hopefully already laughing. Well I have a feeling that there might be a better way to reduce the volatge? Especially since the power the solar cell produces varies incredibly - i think on a cloudy day we would likely get only 1/10th of the theoretical 3 watt. I know there are things like step-down transformers so you can use a 120 Volt device on a 240 Volt poer socket. But for 6 volt to 3 volt?
I know, a good solution would be to use rechargable batteries, buy a 2 dollar solar cell charging circuit and be done, but hey, making it easy wouldn't be so much fun, right? So at first I'd really like to evaluate the possibility of running the device completely from a solar cell without a battery buffering it. How do these 2 dollar solar calculators do that without risking supplying too much voltage or power during peak times?
Imho the perfect solution would have a little switch so i can select if the solar panel charges the battery (Here comes our cheap charging circuit from china again) or directly powers the palmtop. The switch also makes sense when you use non-rechargable batteries since trying to recharge alkalines can lead to them blowing up, leaking or other nasty problems, right?
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