Need Help to Circuit design for Step-Down Transofrmer 220v to 110v

Discussion in 'General Electronics Chat' started by suchinjack, Jul 28, 2009.

  1. suchinjack

    Thread Starter New Member

    Jul 28, 2009
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    i have ONKYO 806 A/V RECEIVER bought from us 110v need to use this unit in india 220V 60cycles power know!!

    so someone please help me to give about basic diagram of 210v to 110v step-down transformer around 1200W or 1500W also how to get constent output power "220v" so its gives perfect audio and video without power inter fear.:confused:


    Onkyo A/v Receiver power supply details:
    AC 120v, 60HZ,

    power consumption :
    north american: 7.8 A,
    European: 740 W,
    Others: 740 W,


    thanks.
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Are you sure there is not an internal switch to select AC power voltage? I checked the owner's manual, and it mentions different models are available for different supply voltages, but it does not mention a user selectable switch. That does not mean there isn't a switch or jumper inside that can be set for different supply voltages.

    If you go the transformer route, a standard stepdown transformer will work. I suggest you buy one purpose made for the power level you need (i.e., >750W).

    John
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
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    Look for an autotransformer of the proper power and voltage ratings. I use one on my lathe to run the 120 VAC 1 hp motor from 220 VAC. They work great as either step-up or step-down transformers.
     
  4. suchinjack

    Thread Starter New Member

    Jul 28, 2009
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    0
    There is no internal switch or alternative to select AC power like 120 or 220 v with onkyo 806 AV receiver my q is

    *Witch one is simple and safe.. to remove internal 110 ac transformer and fix 220 ac transformer. it may void manufacturer warranty know?

    *If external step down transformer >750W so its possible to choose 1200 or 1500 W, because here input power sum times wary like 180 - 260 v so. otherwise how to stabilize output power.

    thanks..

    suresh









     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    The external supply is simpler and does not void the warranty. John
     
  6. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Where does it spend that much of power? Wow!
     
  7. t06afre

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    May 11, 2009
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  8. someonesdad

    Senior Member

    Jul 7, 2009
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    It sounds like suchinjack has two questions:

    1. How to step down the AC line voltage from 220 VAC to 120 VAC.

    2. How to stabilize the line voltage, which apparently varies.

    I would say ignore the power ratings of the amplifiers, as those appear to be marketing numbers. The relevant number is the AC current rating given by the manufacturer -- 7.8 A at 120 VAC. This gives approximately 1 kVA, which would be a conservative rating for a step down transformer. This answers question #1.

    Question 2, the power line variation of voltage, is harder to deal with. I found a ferroresonant transformer to run an AC load I was making careful measurements on and it worked great, but the load was less than 30 W. I've read some people resort to using a motor-generator set to stabilize the voltage. Other people with more experience on this board will no doubt have some good recommendations, but implementing them will no doubt be more expensive than you had planned on.
     
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