12 Vdc to 10 Vac and 5 Vac

Discussion in 'The Projects Forum' started by worldHello, Oct 15, 2014.

  1. worldHello

    Thread Starter New Member

    Oct 15, 2014
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    So I need to have two inverters.
    The first one is 12 Vdc to 10 Vac
    the second one is 12 Vdc to 5 Vac.

    How can this be done?

    I found a website that introduces inversion http://homemadecircuitsandschematics.blogspot.com/2013/10/pure-sine-wave-inverter-circuit-using.html , but it doesn't seem suitable for my project.

    And I thought about buying inverters instead of building one, but most inverters one can buy are 12 Vdc to 110 Vac. Most transformers are 12 V to 6 V not 5 V or 10 V. How can this be done? Do I have to build it myself?

    Please help me!
    Thank you
     
  2. wayneh

    Expert

    Sep 9, 2010
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    What do you want to power with those inverters and how much power do they need? If they can use a square wave, it's simple. If they need a sine wave, that's different.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    How much current?
     
  4. worldHello

    Thread Starter New Member

    Oct 15, 2014
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    The power should be 2W-10W, and this should be a sine wave. Any ideas? Please.
     
  5. worldHello

    Thread Starter New Member

    Oct 15, 2014
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    Could you tell me your idea of making it a square wave? I have been searching around using Google, and my conclusion is CD 4047 Chip can make a square wave. Afterwards, use a few NE 555 chips can make that a sine wave. However, I haven't implemented this, so I don't know how good this approach is.

    I would like to hear your approach, too. Thank you.
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,432
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    You really ought to say what you are powering with 10VAC and 5VAC, at what frequency and what amperage for each.

    You may want to consider a linear power amp such as LM675 or LM1875.
     
  7. worldHello

    Thread Starter New Member

    Oct 15, 2014
    23
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    Thank you very much. It is a project, so I'm not really powering anything. The requirement only states 2W - 10 W. Frequency and amperage are not specified.
    However, the requirement comes in when looking at the equation for power P = I*V*cos(phi), where phi is the phase shift. Any more suggestions?
    Thank you for the suggestions LM675/LM1875.
     
  8. wayneh

    Expert

    Sep 9, 2010
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    Worst case is you need 2A at 5V to get 10W, or 1A at 10V. If you don't mind a square wave, then all you'd need is a square wave generator driving a push-pull amplifier. You can make a square wave with an op-amp, or a 555, or many other ways. Just about any "power" MOSFETs can handle switching 2A. I have a handful of IRF540N (old, easy to find, cheap) that I would use for this but there are many other options.

    You could reach frequencies up to high-audio or even ~100kHz without much trouble with this simple approach. If you need higher frequencies, the design becomes more specialized.

    Modern DC-AC inverters improve on a square wave by adding a brief step at zero volts in between the peaks to positive or to negative. This begins to look more like a sine wave. The more steps you add, the smaller the error becomes.
     
  9. worldHello

    Thread Starter New Member

    Oct 15, 2014
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    0
    Thank you. Could you say more about the push-pull amplifier? Are you saying we can use a push-pull amplifier to generate a square wave? instead of using 4047 or 555.
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    You still need an oscillator to make the square wave, such as a 555. The amplifier increases the current to the level you need and changes pulsing DC into real AC.
     
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