I was wondering how do you put a LED into your case. I am assuming you can solder it onto a power wire like 5v but isnt that a bit much? What is this resistor and all that, I dont know what I am doing, can anyone help out a n00b.
Welcome to the boards. For direct replcement of a case LED, just solder the LED to the wires you clip off the old one. That's a drop-in replacement. If you want to power your LED directly from the PSU, it needs a resistor in series with it to limit current. We have a handy calculator to help you size the resistor. Ultimately that will be powered by a Molex-style connector back to your PSU in most cases. The resistor can go on either end of the LED, but the LED has a polarity--the longer lead goes to the positive voltage side.
thanks linear! So to get this straight if i use the motherboard headers such as Power LED and HDD Activity LED then i get just drop the LED into the respectful positions on that wire. AND Supplying additional LEDs which come from the powersuplys power need a resistor to limit current. cool. thanks again!
You got it. For multiple LED wiring, we have had a stack of threads how to do that too. http://forums.bit-tech.net/showthread.php?s=&threadid=18083 http://forums.bit-tech.net/showthread.php?s=&threadid=16736 http://forums.bit-tech.net/showthread.php?s=&threadid=15608
Just so I know im on the right track, can you double check my work. Say I have this Ultra SPECS: Bright Blue LED Power Dissipation PD 120 mW Continuous Forward Current IF 20 mA Peak Forward Current IFM 100 mA Reverse Voltage VR 5 V Operating Temperature TA -40~+85 °C Storage Temperature TSTG -40~+85 °C Reverse Current (VR=5V) IR 10 µa View Angle of Half Power 2ø1/2 16 Degree Forward Voltage VF 4.0 3.5 V IF=20mA Peak Emission Wavelength ÿ P 470 nm Luminous Intensity IV 5500 mcd IF=20mA THEN filling in the values on the LED Caculator will give me this: Supply Voltate: 5 Diode forward voltage: 3.5 diode rated current: 20 Caculated Resistance value: 75ohms Next Standard 5% resistor: 82ohms Resistor color markings: grey red black Power dissipated in LED: 64mW Power dissipated in Resistor: 27mW Did I do this correctly? and also where can I find the brightest LEDs on the market?
Calculation looks just fine to me. Brightest? That would be the Luxeon Star/O No camera can do it justice.
Hehe, I remember that review. Did the packaging by any chance come with a warning "Point away from face, may cause blindness"?
Well, there wasn't packaging, but the site I got them from was pretty clear about that. There is now a 5W version (the original are 1W), but there's problems with the useful life, and they are not very consistent in brightness or color (so I hear, I don't have any in hand). The 5W version is $41 or so. I'm working on getting some of these to play with too.
Whats the brightest 5mm LED then not one of those odd shaped own pcb super bright james bond lights thx! I found this site It says there blue LED is rated at 10,000 mcd @ 5v. Is there any other trick to identifying what resistor i need with this inadequate source of information? Size is T-1 3/4
No, not at all. If anything, the LED will probably just be a tad underpowered as power supplies almost never drive the advertised voltage, but just a bit under.
alright so let me get this straight if it runs off 5v or 12v or 7v (7v trick) you can run it directly from your powersupply line and no need for a resistor but if its an odd voltage like 3.5 then you need a resistor? is this correct?
also what is a typical brightness that you use for power LEDs. I dont want to stick a 10cd LED in there and have it blind me from 50 feet away. So what is the typical? 1cd?
well at any rate thx for the help everyone. I found these super bright leds with these specs: Vf@lf(mA) = 3.5@20 Typical MCD @ mA = 10,000 @ 20 Wavelength (n m) 470 Size is T-1 3/4
Just make sure you connect it the right polarity (IE like batteries). You don't wanna blow £2 blue LEDS due to a simple mistake (it shouldn't really happen if you don't exceed the reverse voltage rating which is usually higher than the forward voltage rating.
