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Need help With Limiting Voltage For Lights

Discussion in 'LEDs and Optoelectronics' started by GeneralBones, Feb 8, 2017.

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  1. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Hey guys! I have two stereo receivers, one for music and one for my lights (hooked up to the lower frequenies where a successful would go). I've burnt a few Christmas tree lights and I ordered new LEDs that run at 12v so I wanted to know what I could use to limit the voltage to them so they won't burnout. Right now I'm testing a 10v 2200uF capacitor and it seems like it's working. I wanna see if I could find a scrap 12v one if that's the way to go. And for the Christmas lights, I could probably find a <4v one. Would diodes also work? Keep in mind that I want this to work at different volumes weather it be full blast or somewhat loud. Thanks in advance!
     
  2. GeneralBones

    GeneralBones

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    Jan 24, 2017
    (where a subwoofer***...)
     
  3. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Bump
     
  4. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Bump
     
  5. Audioguru

    Audioguru

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    Sep 24, 2016
    The speaker output from an audio amplifier produces AC that might destroy LEDs that use DC (the D in "LED" is a diode).
    An LED is from 1.7V to 3.5V so maybe yours have a few LEDs in series or have a resistor in series to limit the current.
    The amount of output power from the amplifier determines if the LEDs burn out. A continuous power of only 18W into 8 ohms produces 12VAC. If you electrically limit the voltage or current from the amplifier then it might blow up.
     
  6. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Well it hasn't so far with a 10v capacitor in series with it. The only thing that I think is "burning out" would be the capacitor since the light got dimmer until I connected another 10v capacitor to it in parallel with the other. The lights then became as bright as they did, at about the same frequencies, before I ran the setup for a long time
     
  7. Audioguru

    Audioguru

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    Sep 24, 2016
    A hIgher capacitor value (two same value capacitors in parallel) have double the capacitance of one capacitor. Then they pass lower frequencies and have less loss at low frequencies which will make the LEDs brighter. Most electrolytic capacitors have a + wire and a - wire and should not be used to pass AC so maybe operating the capacitor in series with the LEDs damaged the capacitor with reverse voltage.
     
  8. GeneralBones

    GeneralBones

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    Jan 24, 2017
    So should I buy some diodes to prevent that from happening?
     
  9. Audioguru

    Audioguru

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    Sep 24, 2016
    You seem to be designing an LED and capacitor destroyer instead of collecting important spec's and making a few simple calculations.
    1) Please post the datasheet for the 12V LEDs so we can see the value of the built-in resistor that limits the current.
    2) Please post the manufacturer's name and model number of the amplifier so we can see its maximum Whats (exaggerated) or real Watts.
    Then we can design a rectifying LED driver using resistors and diodes.
    Is there a lowpass filter in the amplifier that would feed a subwoofer?
     
  10. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Okay it's kinda late RN and I have to sleep because I'm busy tomorrow but I'll reply sometime around/after 12pm tomorrow.
     
  11. GeneralBones

    GeneralBones

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    Jan 24, 2017
    Alright so the amp is an MX-GT90 By JVC and here's the link to the LEDs I got:
    Look at this on eBay http://www.ebay.ca/itm/111863385801
    My options were 5M 300LEDS cool white 3528
     
  12. Audioguru

    Audioguru

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    Sep 24, 2016
    The JVC subwoofer amplifiers have maximum average output voltage of 28V with peaks at 40V.
    The LED strips use 12V. If you connect two LED strips in series then they will operate on 24V and use a full-wave rectifier bridge module to convert the audio AC to DC. Do not connect a capacitor and do not turn the volume up to maximum.
     
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