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kachew

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Posts posted by kachew

  1. dear au,

    You cannot buy a transformer that is 8.5V-0V-8.5V to 220V. You buy one that is 220V to 8.5V-0V-8.5V instead. For it to pass 188W continuously then its 8.5V winding must pass 15.7A continuously. The current rating for its high voltage winding is not mentioned.


    what u mean by this? i cant understand....last time u called me to buy a step up transformer...now u said i need a step down transformer???
  2. dear au,

    i found from one of the inverter side and they given some formula which they have different calculations from you which is:

    1) to convert amps to watt:
    multiply: amps*220(ac voltage)= watts
    which is my amps for the transformer will be approximately become 0.68amps

    for example, u have a freezer with a continous load of 4amps and start load of 12 amps:

    4amps multiply 120volts=480watts continous
    12amps multiply 120volts =1440 watts starting load

    after i calculate this result is very different from your result...can u explain the different between this.....
    as i know 15.7Amps transformer is very bulky and expensive....my motive is to make simple and check msw inverter....
    can u help me on this?? thanks alots.... your help is highly appreaciated

  3. dear au,

    means that the output of the modified square wave will be a Vrms value? from the we multiply by square root of 2 to get the peak value? means 230 from the output of the transformer will multiply with square root 2 to get the peak value?

    The transformer will have the same average 376W as before but the peak current in the Mosfets is 2-root-2 times 31.4A= 88.8A.

    what do u mean by this statement?

    how do you know that i must choose 8.5-8.5 instead of 10-0-10V transformer? can give me more explaination about this??

    do i need to reduce the mosfet if i am making the 150w instead of 500w? as i know the mosfet is use for switching only....i think its doesnt affect much on the output value...??

    thanks agian
  4. dear Au,

    A 150W load on an inverter will use about 188W from the battery. Then the current from a 12V battery through the Mosfets and into the transformer is 188/12= 15.7A.
    so the transformer i need is the center tapped transformer(12-0-12 to 220V) with 15.7A multiply 2=31.4 or higher amps step up transformer for which to have continous power of 150W and surge capability of 300W with the overloading protection fuse (300W) to meet all my requirement?
    thanks again
  5. Dear AU,

    the surge capability is the amount of the voltage needed to start an appliance....Multiply: WATTS X 2 = Starting Load, for inverter of output has 150W need to have a surge capabilty of 300W. how can i archieve that? by increasing the transfomer higher rating amps? (buy transformer that have more amps?).... i saw the inverter sold in the market which has rating of surge 300W but have overloading protection of 150W....so what is this means? i though is the inverter has the rating of 300W, it's aleady higher than the 150W how can the overloading protection can work appropiately?
    thanks

  6. dear Au,

    can i know how much the current will flow to turn on the mosfet for switchin? and if i wan to get an output for 150W but not 600W but using the same circuit can it make it? as i know if i buy a smaller transformer as i asked the shopkeeper, the battery which supply 50A to the transformer which is 10A will blow the transformer off....can i know wat is the amps input will go to the transfomer? how can i calculate the output current of the transformer....i still cant get what u mean by previous post....
    your help is highly appreciated.

  7. dear Au,

    means that the mosfet will draw 50A from the battery and each of the mosfet can withstand a current of 23A, so the current from battery will 50A divided by 3 mosfet so each of them draw 16.7A from the battry? is this what u mean?  about the heating power ....how u know i will dissipate 100w? 1 more question, as i know the amps value also must take into consideration when wan to buy transformer....how can i know the amps value?

  8. hi Au,

    how can i know how much currents flows in my circuit? izzit the same amount of current as shown in the datasheet for the mosfet? how many amps of current will flow to the transformer and what is the output amps and voltage as the modified sine wave circuit is recommeded by you....isnt the amps and voltage value for the circuit is controlled by the transformer? depends on the step up transformer voltage and amps rating since the mosfet is use to share and drawn current from the car battery?
    thanks for your reply... :-* :-*

  9. dear Au, i did the corrected version but still no avail, mayb the IC hav destroyed by me... cos i have wrongly connected the supply to the pin 13.... will it burn the ic? i will try with new IC of CD4047 to retry.... is there any other compatible IC can be used to replace this function generator IC? oh ya... i more question.... how can i modified the circuit and use the mosfet for amplification? as i know previous thread u told me that mosfet will get hot easily when amplification occur....so i have built another circuit which is 12V fan temperature control to cool my inverter circuit....can this be done??
    thanks Au

  10. hi all,

    i have tried the CD 4047 and i cant get the desired output from the Oscilloscope....can anyone pls help me?
    i cant get the square wave pulse from it....i have connected a +12V supply  and ground (which is connected to -VE supply with a wire) from a DC power supply at my lab. i have connect it according to the design....any mistake there...if yes pls help me to correct it.... thanks alot :-* :-*

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