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RestlessMind
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I am constructing a solar powered nightlight with http://i538.photobucket.com/albums/ff341/the_cake_is_a_lie/ElectronicsSchematicCOMPLETECUSTOM.gif" circuit, and I have a few questions.
1. I do not know what amount of ohms the resistor designated "R4" should be. I think I can calculate it with: (ohms needed) = (battery voltage) - (LED voltage) / (LED amperage). The package of my battery says that it is 3.6V, and the LED package states "FW current: 25mA, FW supply: 3.3V (typical), 3.6V (max.)". Therefore, is it correct to calculate the needed ohms of R4 like this?
3.6 - 3.3 / 0.25 = 1.2 ohms
Also, do 1.2 ohm resistors exist? If not, what should be used?
2. A solar nightlight tutorial recommends use of http://www.anybodyburns.com/pathlight/images/batteries.jpg" battery that says "Cordless Telephone" on the package, but is also a NiCad rechargeable battery (at 3.6 volts; there are actually three batteries in series in the case). Is this okay, or is there a special property of the tutorial's batteries that were meant for solar applications that mine don't have?
3. Does the circuit, given the above confirmations, seem that it will be functional to you (of course I will test as well)?
1. I do not know what amount of ohms the resistor designated "R4" should be. I think I can calculate it with: (ohms needed) = (battery voltage) - (LED voltage) / (LED amperage). The package of my battery says that it is 3.6V, and the LED package states "FW current: 25mA, FW supply: 3.3V (typical), 3.6V (max.)". Therefore, is it correct to calculate the needed ohms of R4 like this?
3.6 - 3.3 / 0.25 = 1.2 ohms
Also, do 1.2 ohm resistors exist? If not, what should be used?
2. A solar nightlight tutorial recommends use of http://www.anybodyburns.com/pathlight/images/batteries.jpg" battery that says "Cordless Telephone" on the package, but is also a NiCad rechargeable battery (at 3.6 volts; there are actually three batteries in series in the case). Is this okay, or is there a special property of the tutorial's batteries that were meant for solar applications that mine don't have?
3. Does the circuit, given the above confirmations, seem that it will be functional to you (of course I will test as well)?
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