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Help needed in push-pull circuit for Inveter.

Discussion in 'General Electronics Chat' started by koolguy, Oct 2, 2012.

  1. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    Yeah i would not be surprised if every modern converter on the market today uses a uC chip (DC input, AC output). Many PC power supplies sill use the old TL chips or similar but that's a DC output with AC input.

    I think he's looking for ultra simple single pulse type 'modified' sine converter.

    It sort of cracks me up that they even call that a "modified sine". Yeah it's modified alright, modified soooo much that it's not even a sine anymore but just a pulse <big chuckle to follow>.
     
  2. Miles Prower

    Miles Prower Member

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    Why make it more difficult than it needs to be? Here's a design I came up with a few years back (attached). If you don't require logic control, so much the better. Use a MC74HC04A hex inverter as the driver. Connect three of its gates in parallel to drive each phase. These can source/sink 20mA each, so that's 60mA of possible drive current.

    Figure the operating frequency:

    f= 1 / [2ln(2)RC] (Where C is the timing capacitors C3-4 and R is the base resistors R5-6)

    If you're using a common, line frequency xfmr, set the frequency to 50Hz or 60Hz, as applicable. No duty cycle problems as the collector coupled multivibrator generates two signals in anti-phase naturally. The use of a CMOS logic gate as a driver unloads the oscillator to improve its frequency stability.

    Used this to make a 12Vdc-to-4KVdc inverter that runs at 21.6KHz. Works just great.
     
    Last edited: Nov 28, 2012
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  3. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    Interesting, whats the control input from?
     
  4. dave

    Dave New Member

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  5. Miles Prower

    Miles Prower Member

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    ^
    |

    This inverter is a subsystem for a basic "light show" made from an ES CRT. This was part of the +/-2000V needed to light up the CRT. The deflection voltages coming from the R and L channels of a stereo. This draws random squigglies on the screen.

    The CNTL signal was derived from a logic circuit that sensed the absence of a signal that prevented a dead spot from staying on the screen. When the CNTL line drops, the driver transistors cutoff, removing the high voltage from the CRT.
     
  6. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    Cool :)
     
  7. koolguy

    koolguy Active Member

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    Anyway, i have gone to UPS production company in my town the owner was an Engg he inform me that in my circuit to add the short ckt protection at every Mosfet. please help.
     
    Last edited: Dec 1, 2012
  8. koolguy

    koolguy Active Member

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    can one here can help me with this...??
     
  9. koolguy

    koolguy Active Member

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    Hi,

    The SG3524 is working but the problem is the square wave which is not efficient as more current is draw at no load than modified sin wave...
    can u please help me with modified wave circuit with voltage regulation..

    thanks
     

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