High voltage

Discussion in 'The Projects Forum' started by darshelectro, May 24, 2007.

  1. darshelectro

    Thread Starter New Member

    Jan 22, 2007
    5
    0
    This is my first time using audio transformers, and i want to make sure i get my calcs correct.

    Could you tell me how you would work out what the voltage output on the secondary side will be , if 9 volts from an ac supply was applied on the primary side of the transformer.


    More detail:

    The 9 volt supply is from a 9volt DC supply. A 555 timer with and transistor on the output will allow the transformer to operate, as the 555 timer will generate square wave. I need a output voltage above 150 Volts and below 230 Volts. I have attached a sample drawing of the circuit.

    Below is my calculation:

    Primary side:
    9 volt supply, resistance 75 ohms, therefore current 0.12 amps.

    Is/Ip = (Zp/Zs)^(1/2)

    Is= Secondary current, Ip=Primary current , Zp= primary impedance, Zs= Secondary Impedance

    Is/Ip = (1200/8)^(1/2)

    Is/Ip = 12.2 * Ip

    Is= 12.2*0.12 = 1.2 amps

    Secondary voltage = (V=I*R) = 1.2* 1 = 1.2 Volts , should be over 150 Volts

    The electronic guy has told me that this circuit does produce volt over 150 Volts, as he is away and i am trying to get my head around this, do you know where i have gone wrong?

    If so can you correct my mistake?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Working off the turns ratio, the voltage step-up is 150 (1200/8). With 9 volts driving the primary, that will give you 1350 volts out. For 150 volts, the turns ratio should be more like 16.66.
     
  3. pebe

    AAC Fanatic!

    Oct 11, 2004
    628
    3
    Could it be that he has used an output transformer for matching the 1200Ω output impedance of an amplifier to an 8Ω loudspeaker?

    If so the transformer will have a turns ratio of 12.2:1
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    If that's the case, then the output voltage will be close to 105.
     
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