supertrogdor
05-12-2006, 07:37 AM
So most of us have the chart Tim offered for what resistor to use, and others of us use a resistor calculator that can be found here
http://led.linear1.org/1led.wiz
But supposing you got the wrong resistor. Last night after i finished soldering some powerleads to the LEDs for my next build i connected it to power to test it out and it was EXTREEMLY brighter than my other saber. I tried fresh batteries on both counts because i thought that the difference was abnormally high. Now don't get me wrong, i am pleased about this, hoever it makes me think that i royally screwed up the resistor on my other saber and it should be substantially brighter.
So here is what i did. I looked at the technical datasheet from http://www.lumileds.com/pdfs/DS46.PDF and it has a variance of 3.03min to 4.47max with a 3.7typical for forward voltage for the white-royal blue, so i plugged in all the available options into the aforementioned resistor calculator, and came up with the following results.
@ 6volts and 700mA remaining constant
3.03 forward voltage ==>4.7ohm 2.3 watt resistor
3.7 ==>3.3ohm 1.6 watt resistor
4.47 ==>2.2ohm 2 watt resistor
Now obviously tim sells a 2.2 ohm 5 watt because if you cant find the right resistor then you need the next higher number as i understand it. So obviously we want our sabers to be as bright as possible and would therefore shoot for the highest output possible, right?
So i have a couple of questions for those more intelligent than myself with regard to electronics.
as the resistance gets lower(from 4.7 to 2.2 ohms) i understand puts greater strain on the circuit, but lets more current through, right? And if that is so, is there any potential danger to your LED by running the lower resistance circuit? I also noticed that while pluggin in info on the lux 5 and even some dimebag LEDs (blue) from radioshack that it gives a suspicious warning about the forward voltage numbers being too high, double check before wiring the circuit but we will calculate it anyway. Does anyone know why that is? I will admit to being rather ignorrant with regard to electronic circuits, but i am anxious to gather more information. Any assistance here would be greatly appreciated, and i will be getting a new resistor to test my theory as well.
cheers
http://led.linear1.org/1led.wiz
But supposing you got the wrong resistor. Last night after i finished soldering some powerleads to the LEDs for my next build i connected it to power to test it out and it was EXTREEMLY brighter than my other saber. I tried fresh batteries on both counts because i thought that the difference was abnormally high. Now don't get me wrong, i am pleased about this, hoever it makes me think that i royally screwed up the resistor on my other saber and it should be substantially brighter.
So here is what i did. I looked at the technical datasheet from http://www.lumileds.com/pdfs/DS46.PDF and it has a variance of 3.03min to 4.47max with a 3.7typical for forward voltage for the white-royal blue, so i plugged in all the available options into the aforementioned resistor calculator, and came up with the following results.
@ 6volts and 700mA remaining constant
3.03 forward voltage ==>4.7ohm 2.3 watt resistor
3.7 ==>3.3ohm 1.6 watt resistor
4.47 ==>2.2ohm 2 watt resistor
Now obviously tim sells a 2.2 ohm 5 watt because if you cant find the right resistor then you need the next higher number as i understand it. So obviously we want our sabers to be as bright as possible and would therefore shoot for the highest output possible, right?
So i have a couple of questions for those more intelligent than myself with regard to electronics.
as the resistance gets lower(from 4.7 to 2.2 ohms) i understand puts greater strain on the circuit, but lets more current through, right? And if that is so, is there any potential danger to your LED by running the lower resistance circuit? I also noticed that while pluggin in info on the lux 5 and even some dimebag LEDs (blue) from radioshack that it gives a suspicious warning about the forward voltage numbers being too high, double check before wiring the circuit but we will calculate it anyway. Does anyone know why that is? I will admit to being rather ignorrant with regard to electronic circuits, but i am anxious to gather more information. Any assistance here would be greatly appreciated, and i will be getting a new resistor to test my theory as well.
cheers