(01-12-2012, 05:21 AM)ulao Wrote: good to know. Meany say the wave lengths make a difference in receiving. One would ask, how can you tell what X bar puts out? Also, assuming the power the light puts out would make a difference as well. If so why do the wireless bards run off of 4.5 where the wii uses a 12 volt source. If you have an LED and increase the voltage this will change the brightness, just as changing the resistance ( lower ) increases the brightness.
I = E/R or R = E/I or E = IR
( I ) Current
( E ) Voltage
( R ) Resistance
Brightness or "Power" would be the amount of current times the voltage level at a given point measured in watts.
Sure, but you don't know how those LEDs are connected to the power source internally, they might be in parallel in one of the bars and in series in the other one, and there might be additional resistors included somewhere. You just can't know if you don't unscrew it. Unscrewing it and measuring the voltage directly at the LEDs would indeed tell you something.
Measuring the power the bar takes is slightly better, it at least gives you some information. However, it's not a very reliable value, as one of the models might be more efficient than the other one, or the LEDs used in one model match the detector wavelength better.
The real energy emitted is difficult to measure with household means. I think most motion detectors work with infrared, so if you have one, you might be able to use it for that (however you'd need to move the bar with a stick or so in order not to stand in the way... could be a fun experiment ;D). Doesn't make much sense, tough.
The wavelength is indeed connected to "how good it works", Most detectors detect a specific wavelength, a digital camera will detect something like 400 to 800nm, which is the same as your eyes. Your microwave uses waves with wavelengths around 15 centimeters. Those IR sensors detect wavelengths around 1000nm = 1um; that's why candles work so well, if you look at this diagram:
http://upload.wikimedia.org/wikipedia/commons/0/0e/BlackbodySpectrum_loglog_150dpi_de.png (the horizontal axis is wavelength, and the sensors you use detect the waves best where the "1" is)
Candles have a temperature of around 1400°C, so you see they emit most light in that wavelength (so most light they emit is actually infrared, and not visible; that's (at least part of) why lighting bulbs are so ineffective, by the way).