Don't know what Resistor to use

Discussion in 'Xbox - Hardware mods' started by Guarino, Mar 14, 2011.

  1. Guarino

    Guarino Member

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    Im am placing some 5mm UV LED's in my 360.

    I have ordered the LED's already but dont know how to find out what resistor I should use,100, 180, 220 ohm, just have no idea, and I have tried figuring out the calculator for this but not really understanding much of it.

    So I was wounding if someone could please help me out
    I am wanting to use 8-10 LED's

    Here are the spec's on the LED's.

    http://alan-parekh.vstore.ca/uv-led-5mm-3000mcd-p-16.html

    LED Specifications

    Emitted Colour : UV (ULTRA VIOLET)
    Size (mm) : 5mm T1 3/4
    Lens Colour : Water Clear
    Peak Wave Length (nm) : 380 ~ 400
    Forward Voltage (V) : 3.2 ~ 3.6
    Typical Voltage (V) : 3.4
    Reverse Current (uA) : <=30
    Luminous Intensity Typ Iv (mcd) : 2000 ~ 3000(Max)
    Life Rating : 80,000 ~ 100,000 Hours
    Viewing Angle : ±10°
    Absolute Maximum Ratings (Ta=25°C)
    Max Power Dissipation : 80mw
    Max Continuous Forward Current : 30mA
    Max Peak Forward Current : 75mA
    Reverse Voltage : 5~6V
    Lead Soldering Temperature : 240°C (<5Sec)
    Operating Temperature Range : -25°C ~ +85°C Preservative Temperature Range : -30°C ~ +100°C
     
    Last edited: Mar 14, 2011
  2. Guarino

    Guarino Member

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    *BUMP*

    Anyone?
     
  3. TreePro

    TreePro Regular member

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    Assuming you will use the 12 volts of power the LED you selected according to the sites calculator you will need a 330 ohm .5 watt per LED. Or up to max of 3 in series a single 68 ohm .25 watt resistor in series with LED's. To put 8 in series you would need min 28 volts so max of 3 in series at 12 volts.
     
  4. Guarino

    Guarino Member

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    So how are you saying I should wire this up? From my understanding my options would be : One resistor per set of 3 LEDs will use one 68 ohm .25 w? (or) 8 LEDs with one 330 ohm .5 w?
     
  5. Guarino

    Guarino Member

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    okay how about this, what resistor should I use if I wanted to use 8 LED's and have one resistor per LED?

    Sorry, I love doing this kind of thing but when I go to the calculator I just dont understand how it works..
     
  6. TreePro

    TreePro Regular member

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    330 ohm .5 watt per LED if you use a 12 volt input.
     
  7. Guarino

    Guarino Member

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    So much appreciated!!
     
  8. TreePro

    TreePro Regular member

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    No problem, glad to help. Remember to observe the polarity on LED, positive to Anode or it won't work.
     
  9. Guarino

    Guarino Member

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    What do you mean exactly?
     
  10. TreePro

    TreePro Regular member

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    Diodes will only allow current to flow in one direction So, you must connect them properly. A LED is a Light Emitting Diode. The longest lead is the Anode so positive is connected here. There is a flat spot also on most led's which is Cathode (shorter lead) and the negative is connected here. All LED's have a maximum continuous current, if exceeded they will burn out so, that is why resistor is needed to limit current. Different voltage require different resistor for same type LED.
     

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