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Thread: Voltage Regulator Constant Heat

  1. #11
    Constant Bitrate BassBinDevil's Avatar
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    The regulator could be oscillating; they can do that when there's no load on the output. Try putting a small capacitor across the output, like 0.01 to 0.1 microfarads. One across the input wouldn't hurt either.

  2. #12
    Low Bitrate
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    When not connected to mp3 player, the current draw is 300mA ---> 3.6W, with mp3 player, its over 500mA (off ammeter's scale)

    The 7805 I have has the plastic coverings and has the markings ueML (mu epslon M L) then under it 7805A.

    I tried putting a .1uf capacitor on the input and output, and it didn't reduce the heat.

  3. #13
    Low Bitrate
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    I went to another local radio shack and found the exact same model of 7805, identical umEA print on it.

  4. #14
    Constant Bitrate strohmrs's Avatar
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    Unless you're willing to get one from another source, I wouldn't worry about the unloaded heat. It's still operating within normal specs when loaded. The temp isn't that bad as long as the space you put it into isn't too small and you already have it heatsinked. Try the install and monitor it closely for any signs of overheating the first few uses.
    Rick S.

    XP Pro SP2, Soyo P4RC350 MB, Nvidia FX5200, 320W PS, Inverter & uSDC20D, 2.4GHz CeleronD320, 512MB DDR, 30GB 3.5", Pioneer 106s Slot DVD, Linksys WMP54G WiFi, Lilliput 7" & 4" TFT LCD, Zippy EL610 Keyboard, Touchpad, Garmin GPS V

  5. #15
    Low Bitrate
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    OKOK I'll take it up the ... from shipping. What online store can a voltage regulator that doesn't make my heatsink sizzling to the touch?

  6. #16
    Variable Bitrate mp3hombre's Avatar
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    How have you wired it up?

  7. #17
    Low Bitrate
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    Quote Originally Posted by mp3hombre
    How have you wired it up?
    The input souce is a DC wall adapter that puts out 7.5V 800ma

    Pin 1 - input 7.5V wire
    Pin 2 - ground wire from the input, and ground wire to output
    Pin 3 - output wire 5V

  8. #18
    Constant Bitrate strohmrs's Avatar
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    You may want to try hooking up 12v from your battery as the power input. The 7805 will output 1A or 1000mA. It may be working too hard to regulate the output with only 800mA coming in.
    Rick S.

    XP Pro SP2, Soyo P4RC350 MB, Nvidia FX5200, 320W PS, Inverter & uSDC20D, 2.4GHz CeleronD320, 512MB DDR, 30GB 3.5", Pioneer 106s Slot DVD, Linksys WMP54G WiFi, Lilliput 7" & 4" TFT LCD, Zippy EL610 Keyboard, Touchpad, Garmin GPS V

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