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Old 21-09-17, 11:27 PM
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Exclamation Need some LED circuit help!

Hey guys, this is a project I've done many times before.
But this time, for some reason things are just not playing ball.

I'm trying to make a custom LED loom for a build, two series loops of two LEDs in parallel to light up a CPU and GPU block. I'm using a +12V (yellow) and GND (black) connection from a 4-pin Molex connector.



I'm using these LEDs: https://tinyurl.com/ycor7jd9
2 in each parallel branch,

In series with a resistor: https://tinyurl.com/ybe9eyty

And this wire (Yes it's got that frustrating I've even checked the wire's datasheet!): https://tinyurl.com/create.php

I'm studying a masters in electronics, and I've done and redone all the theoretical maximum calculations; Everything should work perfectly!

Yet, whenever I switch the PC on, the resistors are becoming burning hot, along with the LEDs! I've continuity checked for shorts, checked voltages, everything seems perfect!

Can anybody with experience with this sort of thing shed some light?

(Mods if this is in the wrong forum please let me know )

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Old 22-09-17, 06:17 AM
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its been a long time since i did this but i don't think you resister is big enough you need a 270 ohm at a 0.25watt , but my maths maybe a bit out thats for a pair , i i seem to recall better to have resister on ground line
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Old 22-09-17, 11:28 AM
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Quote:
Originally Posted by Eddie long View Post
its been a long time since i did this but i don't think you resister is big enough you need a 270 ohm at a 0.25watt , but my maths maybe a bit out thats for a pair , i i seem to recall better to have resister on ground line
Do you know what the best thing is, you're totally right! I'm actually colour-blind, now I check they are 27ohm resistors instead of 270! Fml 😂
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Old 22-09-17, 04:56 PM
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none of us are perfect , and i'm far from it , glad to be of help
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Old 23-09-17, 02:46 AM
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I knew I had a thread that needed updating, thanks guys. FYI the wizard linked in the thread still works. https://forum.overclock3d.net/showthread.php?t=64250 LED wiring configurator
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Old 23-09-17, 05:43 AM
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I knew I had a thread that needed updating, thanks guys. FYI the wizard linked in the thread still works. https://forum.overclock3d.net/showthread.php?t=64250 LED wiring configurator
very handy link Wraith
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Old 23-09-17, 12:40 PM
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Originally Posted by Wraith View Post
I knew I had a thread that needed updating, thanks guys. FYI the wizard linked in the thread still works. https://forum.overclock3d.net/showthread.php?t=64250 LED wiring configurator
Great thread wraith You might have seen it before, but I always use this software (freeware) when I can't be bothered to get out my notepad and paper to work out any kind of circuit calculations! http://www.electronics2000.co.uk/download.php It does so much more than LED resistor calculations, definitely worth adding to your thread

It's definitely useful to be able to hold up a resistor to the screen and compare it to the colours there when you're colourblind! :')

Re-wired it up with new LEDs and 270r resistors this time! Surprise surprise, it works The moral of this story, don't do electronics at 10pm after a full day of work

Unfortunately Maplin (had to get some last minute LEDs as it's a surprise for a friend's build) have no control over their stock, I ordered 4 more orange LEDs to redo it, 3 are in fact orange, but one is yellow. FML >.<
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Old 23-09-17, 06:53 PM
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i didn't even think of checking the web or forum when i posted reply , i did it old school ,, oh god i'm showing my age lol
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Old 30-09-17, 01:29 AM
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i didn't even think of checking the web or forum when i posted reply , i did it old school ,, oh god i'm showing my age lol
I tend to work it out in my head, got to use the masters for something It's reading the bloody resistors that's my problem
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