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Inverter.........!

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by koolguy, Aug 31, 2010.

  1. koolguy

    koolguy Active Member

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    here is schematic of my circuit..!
     

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  2. Dvinchy

    Dvinchy Member

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    To 101. It is really wrong circuit cause the coil has located between the emitter and common clamp of driver. You must have it or other loads put between collector and source supply.
     
  3. audioguru

    audioguru Well-Known Member Most Helpful Member

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    1) You have the 2N3055 transistor connected backwards. Since you show it an an emitter-follower then its collector should connect to the positive supply (you have it connected to ground) and the transformer primary winding should be connected to ground (you have it connected to +25V).
    2) The max allowed supply voltage for a 555 timer IC is 18V but it is spec'd with a max of 15. Yours is 25V which is much too high.
    3) The resistor R3 plus the resistor R4 add to reduce the base current of the 2n3055 transistor to almost nothing.

    If you use a 12V supply so that the 555 is not destroyed then the base current of the 2N5555 can be the 200mA max allowed current from the 555. The output voltage of the 555 goes to only +9.5V so the base resistor has 8.5V across it and can be (8.5V/200mA)= 42.5 ohms. The diode is not needed.
    The 2N3055 transistor saturates pretty well if its collector current is 10 times its base current so its collector current can be only 2A. Then the max output power is only (12V x 2A)= 24W but since the transistor is turned on for only half the time then the output power is only 12W.
    An inverter with an output of only 12W is useless. I can buy a little 75W inverter for $10.00. A 300W inverter costs only $50.00.

    If you want more power then the transformer must be driven with two transistors in push-pull so that there is always one transistor conductiong into the transformer. Since you are using old-fashioned transistors instead of Mosfets then the transistors need to have a driver transistor to provide plenty of base current.
     
  4. dave

    Dave New Member

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  5. koolguy

    koolguy Active Member

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    A.G., pls give the circuit of push-pull & you are saying to provide driver transistor to have plenty of base current but i have seen on increasing base current upto certain limit the output decrease.
     
  6. Dvinchy

    Dvinchy Member

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    Well known that IGBT or MOSFET usualy are controled by the current of the circuit collector-gate (drain-gate for MOSFET). So the load is put in this circuit will really influence the function for power transistor.
     
  7. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Since your 8k resistor plus 1k resistor between the 555 and the transistor limits the base current of the transistor to only 2.4mA then the output current of the transistor is only 24mA but only when it conducts.
    But the output of a 555 has a max push-pull current of 200mA. Then it could use a suitable current-limiting resistor that will give a base current of 200mA to the transistor so the output of the transistor can be 2A.
    Complementary emitter-follower transistors can replace the single 2N3055 transistor for a high current push-pull output.

    If you add a driver transistor in between then the output of the 2N3055 transistor can be 8A if you want.
     
  8. koolguy

    koolguy Active Member

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    now, i have connected 4k resistance, but there is no change in output, pls help.
     
  9. chemelec

    chemelec Well-Known Member

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    The Circuit you previously show is NOT at All Practical.
    It will never work to deliver any power.

    Even with Numerous Changes, It is NOT a Suitable Design.

    Power Inverters using Power Transistors on the Output.
    OR BETTER YET, Two Mosfets.

    A SIMPLE, But Working Inverter. However NOT VERY GOOD.
    Simple Inverter

    A Much More Efficient Inverter that is not too Complicated and works Good.
    Mos-Fet Power Inverter

    So Either LISTEN to this Advice or GIVE UP on your Idea.
     
  10. audioguru

    audioguru Well-Known Member Most Helpful Member

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    You forgot to say where you connected the 4k resistor and did not show it on a schematic so we don't know what you are talking about.
     
  11. koolguy

    koolguy Active Member

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    here is schematic and i have using almost all component like darling ton(508d),mosfet,2n3055. for amplification giving almost same output.
    now, the resistance of 4k is of 2W, pls tell it does matter the watt of resistance??
     

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  12. chemelec

    chemelec Well-Known Member

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  13. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I finished answering you one minute ago about your awful circuit on the other website.
    The 4k resistor is not a voltage regulator and the transistor is still backwards!
     
  14. chemelec

    chemelec Well-Known Member

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    Sorry a Previous Error.

    Here is the Correct Schematic.
    But it is still a VERY POOR CIRCUIT.

    And If the values of your transformer are in Micro-Henries, They are Totally Incorrect for such a Low Frequency!
     

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    Last edited: Oct 16, 2010
  15. koolguy

    koolguy Active Member

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    the transformer shown is not used as same, it is simple step down 18V transformer.

    as you have connected 7812 it limit is 1amp and when i will give 25V with 7amp, i thick it will destroy.
     

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    Last edited: Oct 16, 2010
  16. chemelec

    chemelec Well-Known Member

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    NO IT WON'T.

    The 7812 Will ONLY use the Current Required to drive the 555.
    Even if your battery was 10,000 Amps, it Wouldn't matter.

    This is a VERY BASIC ELECTRONIC PRINCIPAL.
     
  17. koolguy

    koolguy Active Member

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    pls, tell Relation between Henry and no. of turns or voltage.
    as in software (LT Spice), it as for Henry and i don't know how to find output of transformer.
     
  18. chemelec

    chemelec Well-Known Member

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    I Don't use LT Spice or Any Simulation Programs, So I can't help you on that!
     
  19. koolguy

    koolguy Active Member

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    But you are saying that the transformer are in micro henry??
     
  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    A transformer for a frequency of 100MHz uses inductances in hundreds of micro-henries. I think your transformer is for only 50Hz so its windings must have inductances much much higher.
     
  21. chemelec

    chemelec Well-Known Member

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    For a frequency of 50 Hz and 24 Volts on the Primary, You Probably need an Inductance of around 100 Milli-Henry.
    (100 Milli-Henry is 100,000 Micro-Henrys.)

    Electronics is Somewhat Complex and you have NO Understanding of what your doing.

    And a Simulation is also complex, Typically using IDEAL Parts that really don't Exist.
    Unless you can Enter PRECISE Info, it won't simulate correctly.
    And Even if you Simulate this circuit correctly in LT Spice, it is still Unlikely to work the way you want in Real Life.

    Now IF Your Actually Building this:

    Remove the HV Secondary winding of a 220 Volt Microvave Transformer.
    (BE CAREFULL to NOT Damage the 220 Primary.)

    Next, Wind About 25 Turns of 18 AWG Magnet Wire on it, to use as your New Secondary.
    The Output will now come out of the Origional Primary, Which is Now your Secondary.

    The ABOVE is Only an Approximation.

    However with the Circuit you have, You will Definately NOT get more than a FEW WATTS.
    My GUESS, Maybe around 10 Watts!
     
    Last edited: Oct 17, 2010

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