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120v dc power supply

Discussion in 'Power Electronics' started by swagguy8, Dec 3, 2015.

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  1. swagguy8

    swagguy8

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    Dec 10, 2014
    how can i make a 120v dc power supply for hi fi audio (super flat signal) without the need of a super large regulator or capacitor? (the capacitor would have to be 27000 uf @ 160v)
    any help appreciated
    thanks
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    What has the voltage of the power supply to do with the flatness of the audio signal?

    You will need a big capacitor for that voltage. The capacity depends on the current you are going to draw from the supply.
    The regulator will not be very small either. As you are going for a hifi audio installation, a linear regulator is the preferred choice (unless you are willing to invest in comparatively elaborate filtering which will bring issues of cost and space by itself, in that case a switch mode regulator can be used).

    Note that 120 V DC is a potentially lethal voltage. Take any precautions necessary to avoid electrical shock. The capacitor will store dangerous amounts of energy even after the mains supply has been turned off. Provide a bleeder resistor to discharge the capacitor.
     
    Arouse1973 and davenn like this.
  3. GPG

    GPG

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    Sep 18, 2015
    Switchmode
     
  4. AnalogKid

    AnalogKid

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    Jun 10, 2015
    It sounds like you are talking about an offline power supply making 160 Vpeak after the rectifiers.

    1. The capacitor voltage must be greater than 160 V. 2x the peak voltage is recommended for long-term reliability.
    2. Offline supplies are a banned topic. No gigantic power transformer, no help.

    ak
     
  5. swagguy8

    swagguy8

    73
    6
    Dec 10, 2014
    Can you suggest some linear regulators that i could use for my power supply? I am using the chip LM 4702 as my mosfet for an amplifier.
    thank you for the warning at the bottom, i fully understand the dangers of 120v wall power.
     
  6. davenn

    davenn Moderator

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    Sep 5, 2009
    you do realise this IC requires a split supply ? your comments so far indicate you don't
    so with your stated 120V, I would have to assume that is the total rail to rail voltage ... ie. ... +60V 0V -60V

    for those sort of voltages for audio amp gear, regulation isn't a requirement, the supply rails varying a few volts isn't an issue

    Dave
     
  7. GPG

    GPG

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    Sep 18, 2015
    ??
     
  8. AnalogKid

    AnalogKid

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    Jun 10, 2015
    OK.... I might be confusing different rule sets from different fora.

    ak
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    @swagguy8

    please respond to my comments in post # 6 :)
     
  10. swagguy8

    swagguy8

    73
    6
    Dec 10, 2014
    i have been busy, sorry for the late reply. did the datasheet say it needs a split supply? i didn't notice. i know the maximum operating voltage is 100 volts. How many volts should i use? I heard my dad say that the higher the voltage, the more likely it will sound better, because of better response. if someone can confirm that is the case, then i'll use something around 80-90v, which a dc power supply is a lot easier to make
     

    Attached Files:

  11. BobK

    BobK

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    Jan 5, 2010
    The schematic clip you posted shows +Vcc and -Vee and ground. That is a bipolar power supply.

    Bob
     
    Arouse1973 likes this.
  12. BobK

    BobK

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    Jan 5, 2010
    That chip is not a MOSFET, nor even a MOSFET driver. It is a driver chip for a complementary darlington output stage.

    Also, the max voltage allowed is ±100V, but you don't need that much unless you want 600W into an 8Ω speaker.

    Bob
     
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