Electricians help please

Discussion in 'General Discussions and Advice' started by CW, 12 Jan 2014.

  1. CW

    CW

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    Hi There PPL

    Ive got some questions for the electricians on the forum.

    I need to know.

    If i take 3 x 12v fans with 1.3w (then they 100ma if im correct)
    Can i run these 3 fans in parallel on a 12v 5amp power supply.
    So id actualy need a 12v 300ma power supply minimum but if i use the 5amp power supply it wont do anything cos it will deliver only the amp needed by the fans.
    Which is 300ma, but then i can add fans later if i need to.

    Then second q.
    If i use the same power supply but with 5 x 10w 1amp leds.
    So in parallel the will use 12v and 5amp.

    Ok 3rd q.
    In both scenarios, what happens if one led/fan blows?

    Thanx ppl
     
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  3. cknipe

    cknipe

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    1.3W / 12V = 0.1A per fan. Three fans = 0.3A

    Your 100mA (you sure it's not 1000mA?) will be enough to drive one fan. The 5A supply will be much better yes, and you will be able to add a whole bunch of other fans to that yes.

    You won't be able to run the fans and LEDs from the same power supply, given your LEDs alone are already 5A if I understand you correctly.

    When you overload the power supply, it will heat up and burn out the coils on the transformers. If one of the LEDs or fans blow, provided they are connected in parallell, only the one device that failed will stop working, and the others will continue to run without problems.

    You can supply too much Amps safely, it won't harm the equipment.
     
  4. CW

    CW Thread Starter

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    Great thanx man.

    0.1a is mos 100ma right?

    Ive tried 5x 10w leds in parallel on that driver but the leds just keep on flashing.
    2 of these:
    [ame="http://www.ebay.com/itm/10W-Square-6000K-6500K-White-LED-Light-950LM-120-Degree-FX-/151204522220?pt=US_Car_Lighting&hash=item23347de8ec"]10W Square 6000K 6500K White LED Light 950LM 120 Degree FX | eBay [/ame]

    and 3 of these:
    5X10W Square Cool White 10000K Royal Blue 450nm 455nm High Power LED Light Bulb | eBay

    Im using this power supply:
    [ame="http://www.ebay.com/itm/Switching-Power-Supply-Driver-12V-5A-60W-for-LED-Strip-light-Display-220V-110V-/310840773721?pt=US_Radio_Comm_Device_Power_Supplies&hash=item485f8dcc59"]Switching Power Supply Driver 12V 5A 60W for LED Strip Light Display 220V 110V | eBay [/ame]

    Its adjustable then it measures lowest 11v and highest 15v
     
  5. Istio

    Istio

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  6. cknipe

    cknipe

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    Yeah - from what you posted, you have LEDs, and a Power Supply. You don't have a LED Driver.

    Given the high current of the LEDs, you would most certainly require a driver. They are flashing because they drain the power supply, and the power supply then switches off and back on. You are seeing fluxuations between 11v and 15v because the power supply switches off and on so quick that your meter doesn't have time to go all the way down to 0v.

    It -may- work better to connect 5 rows in parallell consisting of 2 leds in series, but they will be fainter, as the power supply won't have enough current to run them at their full intensity.

    The right thing would be a propper LED driver - more than likely towards the 80W region as you don't ever want to run power supplies or drivers at their maximum rating - they won't last very long if you do.
     
  7. CW

    CW Thread Starter

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    I do have the right drivers for the leds.
    I was just thinking if i could use this power supply to save some space in the control box.

    Got these drivers:
    [ame="http://www.ebay.com/itm/10W-LED-Driver-POWER-Supply-85V-265V-900mA-Constant-Current-DC8-12V-IP67-/331102077488?pt=LH_DefaultDomain_0&hash=item4d1738c230"]10W LED Driver Power Supply 85V 265V 900mA Constant Current DC8 12V IP67 | eBay [/ame]

    What i ment by the 11-15 v is when i measure with the volt meter (with no load)
    when i adjust it the min it goes is 11v then while i measure i turn it up to max then it goes to 15v.

    When i keep the volt meter connected and then when i connect the leds to the power supply then you can see the volts drop till 4v then when it flashes it goes up a bit till 10v then drops again.

    So ja, a driver is better.

    Thanx for the info.
     
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