=> P = V^2/R with this formula I get around 0.33 watts?Is this not correct?
I used the following formula to calculate the ohms:Basically though, if you want 20mA, the resistor should be ([supply voltage] - [led voltage]) / 0.02. Or 50*(supply voltage - led voltage).So I calculated: 5V - 3.5 (led voltage) / 0.02 = 75 ohms=> P = V^2/R with this formula I get around 0.33 watts?Is this not correct?
About the 0.25w items on that site: what I don't understand is why there are several items availablestarting from 1 W upwards. Is not this one the actual resistance value?bestyves
So I calculated: 5V - 3.5 (led voltage) / 0.02 = 75 ohms
Since all the values given in the table are typical resistor values they got an error in their database. The values should read 1Ohm, 27kOhm, 560kOhm etc.But I'm not sure about the prices, looks like you have to order a minimum of 1000 Resistors per value? (that would almost match the prices in Germany 5? if you order >=1000)Eberhard
Am I right that 255 is all eight binary values (0-7) converted to decimal again?
Am I correct that shifting out has to be done twice becausethere are two shift registers?On another note, I'll be using 48 leds with 6 shift registers.can the arduino power that much leds? If not, would it be possibleto light one at a time in such a high frequency that it looks likethey are all on?