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12V DC to 14AC 50Hz Inverter

  1. Jul 8, 2009 #1
    Hi there :)
    I need to build or buy an inverter that transforms 12V DC to 14 AC 50Hz. It's for my guitar sinthetizer, i need to play with it in the street with my 12V batteries. I've tried with an 12V->220AC inverter pure sine (from Velleman) but it introduces to much noise in the guitar.
    Any help or ideas I'll be precious.
    Thanks,
    A. Soares
     
  2. jcsd
  3. Jul 8, 2009 #2

    negitron

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    I'm assuming the instrument comes with a 220 V - 14 V AC transformer adapter and you want to replace it with the inverter, yes? If this is the case, you may be able to forgo the intermediary and connect directly to the battery with an appropriate cable. The reason is that nearly all electronics which take an AC supply have a a bridge rectifier, along with some filtering, to convert that AC to DC. The bridge rectifier can also accept a DC input and because of the way it works, the polarity doesn't matter. The other advantage to this is that it will entirely eliminate AC hum as an issue.

    The only possible pitfall I can see is if the equipment uses a transformer (DC causes transformers to saturate) to change the 14 VAC to something else but this is something I've never seen done. There's no point; if you're going to use a transformer anyway, you might as well get one that accepts line voltage and steps it down to what you need. You're pretty safe in trying, I think, as long as you unplug it right away if it doesn't work.
     
  4. Jul 8, 2009 #3
    Hi :)
    "I'm assuming the instrument comes with a 220 V - 14 V AC "
    You're right.

    So do you think it's completely safe to connect an 12V battery directly to the input of the rectifier, althought it's an 14VAC input? Just to see if it works,...
    By the way it's an Boss GR20 guitar sinthetizer. I've contacted an Boss technician and he told me that the sinthetizer need 50Hz for it's internal circuits/effects, I don't know, i doubt it ...

    Thanks, greetings :)
    A. Soares
     
  5. Jul 8, 2009 #4

    negitron

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    I can't state with complete confidence that it's 100% safe--it's conceivable, albeit unlikely, there's some weird engineering going on in there. I can only state with a high level of confidence that I believe it will work, based on 30+ years of dealing with electronics. I completely understand if you prefer not to take my word, especially if it's an expensive piece of gear!
     
  6. Jul 9, 2009 #5

    vk6kro

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    Worth taking the lid off to find out though.
    If the AC input goes to something like this:
    180px-Bridge_rectifiers.jpg


    These are bridge rectifiers and it is probably OK to run the device off a battery or at least to take it to someone who will check it and tell you for sure.
     
  7. Jul 10, 2009 #6
    Hi there :)
    And thanks for your help.
    I've been with a friend, electronic expert. And he said that my sinthetizer Boss GR20 has DC after the bridge (+12V and -12V).
    I'm going to try this weekend with two batteries connected to the right points in the PCB.
    Greetings :)
     
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