I bought 4 of these: Pre-wired LEDs I guess I didn't read the description very well--they are to be plugged into the motherboard....3.3v I just want to wire them together and plug them into a 5v or 12v line..... It doesn't look like they have any resisors on them....so, what do I do with them? Thanx!
Hi Minifly3, Thank you, I pretty much got that, but was hoping maybe I was missing something. I guess I can pick up a resistor at radio shack. Would anybody care to figure out what resistor I need to hook these up to a 5v or 12v line? 12v might be easier for me, but either will do.....4x 5mm LEDs .... Again, electronics are my weak point and that description doesn't give me much to go on..... EDIT: A brief description of the wiring: Mount the LEDs, run the wiring and cut all to a mutual length, strip, twist together, solder, add molex pins. I guess now I will need to add a small length of wire for the common resistor, right? TIA
1/8W or greater 100 ohm resistor. The color code for 100 ohms is brown black brown. I'm pretty sure this is write but maybe someone else can confirm this. (5v) 1/2W or greater 470 ohm resistor. The color code for 470 ohms is yellow violet brown. I'm pretty sure this is write but maybe someone else can confirm this. (12v)
Sorry That Is per led. 4 Is hard to calculate because the supply voltage is less then the total voltage drop.
Hi Minifly3, Thank you for clarifying it for me. I've read enough that it seemed per, but the whole LED, voltage, resistor thing just always leaves me uncertain. I've learn a lot of things over the years, but I just cannot seem to get my head wrapped around this one for some reason..... Maybe one day it will "click"..... I can do per--that's really not a problem....just more work for me. I doubt I'll hit radio shack until this wkend, so if anybody would care to sort out the 1 resistor for me--it would be Appreciated.....!
safe to assume that the LED forward voltage is around 3.3v then (its usually 3.2v but can also handle being overvolted like that, not ideal, but its not a HUGE problem) We also have to assume that the forward drawing current of the LED's is 30mA each, this is typical of blue superbrights and its all we've got to go on. So, lets begin, you can run 4 off the 12v line with no resistor, this is probably you're best option, no fiddling, 4 LED's chained together in series. If say you run 3 in a chain off of 12v then read here.. : 12v - 6.4v = 5.6v 5.6v / 60mA = 93.3 ohms The closest standard value is 91 ohms, thats close enough. And that would be ONE SINGLE resistor for ALL THREE LED's Theres no point using the 5v line, to get any decent number of LED's running you would have to create multiple banks of serial groups of LED's and put them in parallel with each other, would get a bit confusing. If you need any other values or quantities worked out, just shout In which case you would not require a resistor at all, if he is wiring them in serial...
Hi dragon, Many Thanx!--that worked great! I just taped them together in series and they lit right up! I'll do permanent later... Now I could just use some help with this: Modding Sound Sensitive Unit...? Many Thanx!
I wouldn't assume anything from that site's info, I think they've plucked the 3.3 figure out of thin air, knowing it's a "PC voltage". Their "3.3V" also covers their red, yellow and amber LEDs which will certainly be nearer 2V. They are just a plain LED with ready-made lead & connector to do a swap for the stock case LED, which gets 5V current-limited by a "one size fits all" motherboard resistor.
Hey - if you don't have the resistor yet, I think you could just wire them up in serial off of the 12V line so each LED gets 3V. My basic understanding of electricity tells me this should work... yes?
