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Modding a case

Discussion in 'Modding' started by Damianb, Nov 5, 2008.

  1. Damianb

    Damianb Member

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    Ok so me and a mate are going to mod his case and stuff. because we want something to do during the holidays.

    We're going to change his current LED fans colours. so we're buying purple LEDs and doing whole new wiring and putting a switch to turn just the LED's on & off.

    we're using these LED's. there are so many numbers in the specs so i was wondering. what is the Voltage number we should take note of?

    We were going to use a switch like this and i was looking at setting up the wiring like this:

    [​IMG]

    The circles are LED's...

    Will this work?

    Thanks

    DamianB
     
  2. C0L0N3L

    C0L0N3L Member

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    that would work but i dont think series is the most effective way of wiring it.. i think you would be 2v short with that circuit.. and the line up the top seems pointless to me...

    disclaimer: I'm not 100% sure if what I said is correct..
     
  3. OP
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    Damianb

    Damianb Member

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    yeah the line up the top seems to be a mistake by me. lol

    What would be a more effective way to wire it?
     
  4. C0L0N3L

    C0L0N3L Member

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    umm.. reading your post again... are your changing the colour of the LED's in LED fans or making LED fans?

    parallel would be better i think..

    so with out drawing a diagram

    ____~_____+___+__+__+
    ___________-___-__-__-

    ~ resistor not sure what you need depends if you use 5 or 12v
    _+_
    _-_ = LED.. very crude but you should get the idea...
     
  5. slamaa

    slamaa Member

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    He Has wired it in a series/parallel conbination, each row of LED's is in series and each row is set parallel to each other.

    Just remove the wire from the top, it will be fine, You also need a resistor in front of each row of series LEDs
     
  6. C0L0N3L

    C0L0N3L Member

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    are you sure he needs a resistor if they are in series?

    I know how he wired it... but I'm pretty sure they wouldn't be as bright as they could be in series..
     
  7. slamaa

    slamaa Member

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  8. OP
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    Damianb

    Damianb Member

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    Yeah i was thinking. due to them being series/parallell there would be 12v to each parallel

    seeing as there are 4 LED's on each parallel then there will be 3v supplied to each LED correct?

    Also in the description for the switch it says 12v. so i'm assuming that means it uses 12v. if so, will this work?
     
    Last edited: Nov 5, 2008
  9. C0L0N3L

    C0L0N3L Member

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    yep that sounds about right adding a resistor in there would make them really dull.

    yeah the switch is 12v i believe so yeah that circuit is looking good without the extra line
     
  10. OP
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    Damianb

    Damianb Member

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    if their rated voltage is like 3.3-3.7v and 3v is sent through them. will they still work properly?
     
  11. C0L0N3L

    C0L0N3L Member

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    yep they will just be a little dull.. wont be that much of a difference but it would be noticeable.. if you did it in parallel they would all be bright.
     
  12. OP
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    Damianb

    Damianb Member

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    Problem with parallel it will be a lot harder actually wiring it. so we'll go with slaamas design

    Should we just get the weakest resistor we can? or not bother?
     
    Last edited: Nov 5, 2008
  13. C0L0N3L

    C0L0N3L Member

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    i wouldn't bother... i dont see how either are any different in wiring but yeah.. good luck and have fun
     
  14. Ephphatha

    Ephphatha Member

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    I'd wire it with five parallel runs of three LED's and a 50ohm resistor in series. I miscounted and didn't realise you had sixteen already. Do you really need sixteen? You can stick with four runs of four, but I wouldn't advise it. eight runs of two LED's would be better, but then you will need eight 166ohm resistors.

    It'll stop them drawing too much current and burning out.

    The lamp in the switch will be fine though, it already has an included current limiting resistor.

    Edit: All this is assuming you're running the lights off a 12v PSU rail.
     
  15. OP
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    Damianb

    Damianb Member

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    Yeah. i think i've changed my mind again and i'm going with eight runs of 2 leds.

    If i do it like this

    [​IMG]

    How do i wire in the switch?

    sorry about all the nooby questions. i really should've paid more attention in physics when we learnt all this stuff. lol
     
  16. C0L0N3L

    C0L0N3L Member

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    [​IMG]

    you wire those up and put the switch on either side.
    I don't think there is much else on the switch so I don't think it will mater which side of the circuit you put it on or which wires are on which side.. you just need it to open and close the circuit.
     
  17. onoff312

    onoff312 (Banned or Deleted)

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    Or you could get put one 220 ohm in and have it substitute for them all. Might be cheaper - you don't need 8.
     
  18. OP
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    Damianb

    Damianb Member

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    Yeah i spoke to my physics teacher and that's what he said we should do.

    I'll give you updates on this in the next few weeks when it gets up and going.
     
  19. Ephphatha

    Ephphatha Member

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    Time for a little gimp drawing I think.

    The five lines on the right are contacts for the switch, I am using this image as a reference.

    If you want the switch light to be always on, wire it like so.
    [​IMG]

    If you want the switch to light up only when the rest of the lights are on, wire it like this.
    [​IMG]

    I would suggest using 180ohm 1/4w resistors instead of 220ohm 1/2w resistors. The resistors will be dissipating 1/8W so you should be fine unless they get extremely hot from other sources. If you get 1/2W resistors, it doesn't matter as long as they are the right resistance.

    Your LED's pull 30mA and operate at 3.5V. The required resistance is Voltage drop [5V] (Which is given by Supply Voltage [12V] minus the sum of the Forward voltage of your components [3.5V x 2]) divided by the current required in amps [0.03]. This comes out to 166ohms.

    The heat dissipated is given by the Voltage drop multiplied by the current draw, which is 0.15 Watts in that example.

    Given that there is no 166ohm resistor, the next highest is the 180ohm. That will give you a slightly lower current supply or voltage, and thus will dissipate more heat. (0.16 watts or so).

    I would not advise using one resistor, it will have 0.03 * 8 amps running through it and will certainly burn out the moment you turn the circuit on unless you get a 5W resistor. Besides, you can buy a strip of ten 1/4W resistors for 50 cents at leading edge.

    Edit Edit: I'm a little rusty on this, but I'm fairly sure that the other reason using one resistor for a set of parallel components was not advised is because if any part of the circuit has less resistance than the other paths it will draw a greater percentage of current. If one loop fails, then the other seven loops suddenly have to deal with the current. Pretty much, using one resistor means the weakest link will die faster, and when it does the rest of the circuit will suffer (the next weakest will die even faster, the next weakest after that will die even faster, once four loops are down the rest of the LED's will burn out almost instantly).

    Edit: I apologise in advance for any factual errors, I haven't had to do any electronic work for a while.
     
    Last edited: Nov 6, 2008
  20. OP
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    Damianb

    Damianb Member

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    Ok great. thanks

    We've decided to have the switch light to be always on

    What if it was done like this:

    [​IMG]

    Would that work?

    Voltage drop = 12 - 3.5
    / .03 = 283.3 ohm
     

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