Need Inverter Ckt

Discussion in 'The Projects Forum' started by s2pk, Dec 25, 2010.

  1. s2pk

    Thread Starter Member

    Jul 10, 2010
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    i need 12V DC to 220V AC 100watt inverter circuit, plz post a simplified and tested ckt
     
  2. s2pk

    Thread Starter Member

    Jul 10, 2010
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    [​IMG]

    i have got this simple ckt but the output voltage is 120 v, so in order to get 220 v i just have to set secondary winding or some additional components would also be required???
     
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    The picture features a 120/12 volt transformer.

    If you build it using a 240/12 volt transformer, then you will get 240 volt output.
     
  4. Tahmid

    Active Member

    Jul 2, 2008
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    Hi,
    Just change the transformer to one with a 240V primary winding.
    Don't expect good results from this simple circuit though, it is not frequency or voltage stabilized and it has no overload protection. It also has no protection against battery deep discharge, so you may have a dead battery if you run it for too long. I think no matter what the wattage you should use a good inverter circuit. For simplicity you could build one around SG3525, MOSFETs in push-pull mode and use opamps and comparators for overload and short circuit protection.

    Hope this helps.
    Tahmid.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    The simple circuit shown in post #2 is not good at all.
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Since it's 240V I'll assume 50 Hz is what you're wanting. It's often easier to buy rather than build one of these but if you make a decent 50 Hz oscillator from a 555, add a stage to make a second output at 180* out of phase then feed MOSFETS into the transformer you'll end up with a fairly decent workable circuit. The output will be more like a square wave than a sine so you will want to experiment with some caps in parallel with the driven windings on the transformer and of course include the proper snubber diodes.

    Sometimes I think I should have asked for a drawing tablet instead of a 27" monitor for Christmas but I'll buy one some day so I don't have to fire up my design software just to produce a simple schematic.

    If you want to get a bit more complicated but exact try and learn something from these circuits:
    http://www.m0ukd.com/electronics/modified_sine_wave_inverter/
    http://www.m0ukd.com/electronics/modified_sine_wave_inverter/MOSFET_Inverter.jpg

    [EDIT:] I don't like the referenced MOSFETS in those circuits, use something that's far more logic level friendly.
    I also wouldn't worry about the 10V specs on the transformer's windings, a 240V:24VCT rated for 50 Hz should work fine.
     
    Last edited: Dec 25, 2010
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    I've seen the Wacom Bamboo down to around $50 for some 4x6 models, excellent deal! Larger ones are nicer though, I don't often use more than 4x6 on mine, but it makes a nice hand rest.
     
  8. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I've heard of those but I would like one that has direct feedback on the actual drawing surface rather than having to look at the screen as I draw. I guess if you put a piece of paper on it then it matters not. They're totally new to me so I'm going to research a lot before I consider putting one on my list of things to buy next

    Personal funds are kind of limited at the time being so I'm being very careful on that matter as you never know if something's going to come up with your car or whatever so I've got to keep a decent reserve. Got my 27" monitor though, sure hope if can match the color rendition and geometry that I can attain with this 19" Professional Hitachi CAD monitor. I've got a 21" Mitsubishi Pro CAD sitting as a spare up at work but it takes two people to move and defeats the purpose of trying to reduce the heat input to my bedroom where I do a lot of my design work.

    If I've got any of my media servers running at the same time I've almost got to open the window after a while. They may be pretty much state of the art as far as new goes but they sure generate a lot of heat which is just a normal downfall from having a quad core processor and 9 drives in the main one, 13 drives in another and a high end graphics card in the third.
     
  9. s2pk

    Thread Starter Member

    Jul 10, 2010
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    i want an IC free circuit
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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    That makes things harder but still doable if you don't mind going with that first circuit posted and refining the design way down to some sort of precision. The circuit will have to be tuned such that it oscillates at the frequency you want and the transistors (often 2N3055 or MJE3055) back when that circuit was first designed will generate a lot of heat so they'll need a good heat sink.

    If you don't mind using a couple of extra transistors you can design a far more accurate driver circuit but, may I ask, are you intending to power with this?

    And what's so wrong about a simple IC such as a 555 timer for the frequency reference?
     
  11. s2pk

    Thread Starter Member

    Jul 10, 2010
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    marshal can u redesign my ckt with and without introducing IC
     
  12. retched

    AAC Fanatic!

    Dec 5, 2009
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    Why do you want an IC free design?
     
  13. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Probably a school assignment.
    Cheaper to buy than build.
     
  14. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I honestly don't have the time nor the test components sitting around, just play with that first circuit until you find some values that net you approximately the proper frequency. I doubt you'll be able to make it accurate but you may be able to get close.
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    What is the intended load for this?

    The output will be nowhere close to a sinewave unless you use an IC based circuit that will produce the "Magic Sinewave" PWM.

    With the multivibrator design above, you won't reach more than a few watts ability with the parts that have been mentioned so far. 1 Amp at 12V = 12 Watts, whereas 1A @220V = 220 Watts. So stepping up a 10Amp 12V (120W) supply through the inverter would result in 220V@545.46mA (120W) The actual output would be less due to losses.
     
  16. Audioguru

    New Member

    Dec 20, 2007
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    The circuit you found has two very long threads on the website it is on that desribe all its problems:
    1) Its capacitors were shown with backwards polarity for a few years so they blew up but recently the polarity is corrected.
    2) The transistors have avalanche breakdown of their reverse-biased emitter-base junctions at fairly high current so the capacitors blow up even if their polarity is corrected. The power is wasted so the output power is very low.
    3) The transistors have a very low base current so the output power is very low.
    4) There is no voltage regulation so the output voltage drops a lot when there is a small load.
    5) The output is a square-wave, not a sine-wave. Adding a capacitor across the transformer winding will produce a sine-wave only when there is no load.
     
  17. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I've seen inverter circuits like these put out 100W using 2N3055 transistors on heat sinks but the output wasn't much good for driving anything other than a light bulb.
     
  18. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    I don't understand why people want to build a 100W inverter, since a 100W inverter is a 3"x3"x1" box on the end of a car lighter plug for $25 or so. That includes a bonus 5V USB jack as well. They don't even get warm, let alone "hot" when charging a couple notebooks.

    I think some circuits like those above that are proven not to work as shown should have a note over the schematic that would link to at least a functional circuit, if not efficient. The site is active enough, and there is enough feedback to show that nobody has gotten it to work.
     
  19. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Sadly it's usually someone in a developing nation with unreliable power looking to keep the electricity running. Hopes eternal that a functional UPS can be had with a couple of random transistors an old clock radio transformer and a half dead car battery. A cheap $25 inverter (almost always the OPs mean UPS but whatever) is a month or two wages so the quest continues forever.

    Here's the part that interests me, since the problem appears to be limited supply but massive demand (nobody seems to want to pay for the electricity) there are constant blackouts done by the power company. People using UPS's simply and selfishly increase the load and if enough folks do it the blackout durations will likely increase.
    [​IMG]
     
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Yea, I know what most want but rarely explain. They spend all their money on "how to" seminars and tapes or DVDs that tell them nothing. If the money was there supply would have entered into the equation a long time ago.

    Never have understood how they can have so many power problems yet their computers and internet connections still work as well as they do. Something's really backwards here as if faced with that problem I'd have a good backup generator first and to heck with the computer until I could afford one.
     
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