Case Mod - In Progress Project: Orange Monster, 26 July 2006; Wire routing blocks 16.3.2014

waitting the final work....

 

Looking forward to this coming update...

 

oh this is freaking sweet cant wait for the update ^_^

 

The update is coming, but I need a bit of help from electronics gurus around here!

I'm using a led calculator and it suggests the right resistor, but can someone tell me why the resistor is on the negative side of the led?

Can't I put the led on the positive lead "before the led" so to speak?

Answers appreciated

Darkened

 

? Every guide I've seen has the resistor near the end of the series... but I'm a novice as well, and I burned out an LED recently.

 

Hope i can see an update tomorrow. Can´t wait.

 

Yes, you can put the resistor at any end you like. I don't know why the people above me suggest otherwise, I've never seen prove that it is supposed to be at the positive or the negatieve pole.

 

i have proof, i put power though the wrong way, with a white led it blow, and with a red led in went orange

 

The only times when I saw a discoloring led was when I set the voltage or the current too high, so I guess your resistor was just chosen wrong.

 

brinkz0r has it right ........ resistor can be on either side ......


Alan

 

nope, there is no need, you need 470 ohm on 12V, the polarity is not of matter

 

It's good to know we got that cleared up.

 

My thoughts exactly

Well if we think about this a bit more, putting the resistor to the positive pole would be natural and it comes to mind first, because it would take the "hit" from 12 volts and reduce it down to 2,5-3 volts, what ever is needed.

I believe that the answer is that there's no difference in which pole you connect the resistor, just make sure the circuit has the right amount of voltage drop for your leds.

I mean, if you think about it, when you put three leds in series, it might just as easily be one led and two resistors in series (which it kind of is).

I'll continue putting the resistor before the led, but if someone knows a definite answer to this one, be sure to write and clear this thing up

For the update, I'll see what I can do, but it'll probably be a post easter update tomorrow, since as it turned out, I needed a day off from dealing with computers and so I haven't done anything today

Well, in any case, I'll put the update up as soon as possible and it'll be a big one...a few things and I can start filling the loop...cool

Sincerely

Darkened

 

I just read through this truly epic thread (took me 3 days) and I just want to say great work Darkened, I love your attention to detail and your taste for all things stylish!

With regards to the LED resistor, it definitely doesn't matter where you put the resistor in the circuit. There will be a voltage across the resistor, say 10V so if the LED is 'before' * the resistor it will look like this:

12v
|
a
|
LED
|
b
|
RESISTOR
|
c
|
0V

so at point a, the voltage is 12V, point b = 10V point c = 0V -> a 2V drop across the resistor.

If you put the resistor 'after' the LED:
12v
|
a
|
RESISTOR
|
b
|
LED
|
c
|
0V

then a=12V, b=2V, c=0V -> 2V drop across the LED.

All that matters is the voltage drop since voltage is only a relative measure.

I haven't connected up any LEDs myself, but I was wondering - is it usual to run them from 12V? It would make more sense to me to use the 5V line with a smaller resistor since that's closer to what's required by the LED... Is there something I'm missing?

Just noticed this on page 1, which made me laugh:

that was in 2006


*(I say 'before' and 'after' in inverted commas because electrons actually flow in the opposite direction to conventional current, i.e. from 0V to 12V since they're negative charge carriers, but that's not really important )

 

I've done lots of leds, single and in series, and I always put the resistor where it's most convenient. Sometimes the 'in'-line (wire coming from the 12V source) is so short I prefer to put the resistor after the last led or even in between leds.
It doesn't matter at all.

And yes ashchap, one could just as easily use 5V as the source but only in the case of single leds (except when you use low voltage leds of course, the most common ones for modders use 3-3.3 V). With 12V, you can make lines with 2-3 leds, eliminating some wires.

 

Thanks for the answers guys, helped me a lot

I have the update ready, well actually I did have it ready yesterday, but my web server isn't working for me for some reason, I can see the old pics, but can't connect via FTP.

I sent an email today to my service provider and hope to get it sorted out by tomorrow.

Sincerely

Darkened

 

I'm going to be wiring up a lot of LEDs in my case project as well. Be sure to well document your experience wiring up LEDs and resistors when you post your next update so I know what the heck to do!

 

get a new server host we are waiting for an
EASTER UPDATE

 

Is the easter update ever coming? I think it needs a new mane anyway....

 

As far as the question about where to put the resistor in a series, it doesn't matter - voltage is the same across the whole circuit. If you use a resistor to limit the voltage to about 10.5 for 3 blue leds in a series, and use a multimeter to measure the voltage on the circuit, it will measure 10.5 (or thereabouts due to how close you can get to the desired resistance - consistant regardless) anywhere on the circuit.

If it mattered what order you put things in, you couldn't put leds in series - or you'd be hitting the first one with the whole 10.5v, the next 7v, then the last would have the right voltage. Luckily, it doesn't work that way. Each led and resistor drops voltage across the WHOLE circuit (which is why each LED is running at 3.5v in the above example).

No, I'm not an engineer, but I had the same question when I did my first LED mod.

Sites like this might help clarify things (specifically the "resistors in series and parallel" section).

Also, if in doubt, get yourself a breadboard and play around with a multimeter!



I love this mod! Keep up the good work and throw us that update already!