AC to DC step up converter. need help ASAP

Discussion in 'The Projects Forum' started by Anosh89, Oct 29, 2011.

  1. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    Hello I am new to electronics.I have a project due in two days. I have to design a 5 V(peak) AC to 8 V DC (step up converte)r. I need to have atleast two designs with following conditions:

    Frequency = 400 Hz.
    Current = 200 mA
    Ripple = 10%.

    I am not sure how to approach this project. Please can someoen help me with the designs. I would really appreciate it. Thank you.
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Do you understand transformers, rectifiers, and capacitor filters? You just need a transformer of the appropriate output voltage conversion ratio driving a full-wave (bridge) rectifier and filtered with a large capacitor. You can Google for many references to this such as here.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    Ummm.... I don't think that will get him from 5V up to 8, and it certainly won't solve the 400 Hz criterion.

    Haven't you (the OP) been in class? They wouldn't assign such a task without first teaching you how it might be accomplished.
     
  4. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    Thank you for your help. That helped a lot to get me started. I am first designing it on Multisim 11.0 to see if everything goes okay.

    I have question regarding the output voltage. Which model of Transformer or either regulator I must use in order to get an output voltage of 8V DC. Thank you.
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Sure it will. All he needs is a 400Hz transformer that will step the AC voltage up a little and then feed it into a FWB and cap filter.
     
  6. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    @ Wayne,

    It is a research based project. I am sorry but I posted my thread to get help, not to get these sort of comments whether if we have done anything in class. Please don't waste your time in writing and others time in reading that.
     
  7. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Is the AC input sine wave or square wave?
     
  8. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    It is a Sine Wave
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    If it is 5V peak input, that's 10V (peak to peak). Run that into a full wave diode bridge and connect to a filter cap and you will get a DC voltage of about 8V.
     
  10. Anosh89

    Thread Starter New Member

    Oct 29, 2011
    7
    0

    Ok so you are saying this is how I should do it..

    5V AC peak source ---> full wave diode bridge --> filter cap ---> 8V DC

    Is that correct?

    I thought we have to use the transformer as well.Do I have to use it?
    Because I cant find a transformer in Multisim whom in can give a 400 hz frequency?
     
  11. BillB3857

    AAC Fanatic!

    Feb 28, 2009
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    Have you ever heard of a voltage doubler circuit?
     
  12. wayneh

    Expert

    Sep 9, 2010
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    Sorry, I was assuming he was starting with lines power at 50 or 60 Hz, transformed down to 5V. Can't really tell. I also assume he means ≤10% ripple, not exactly 10% as stated.
     
  13. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    No sorry I haven't heard about it. Can you please guide me on that. I will appreciate it. Thank you.


    @ Wayne: No according to the instructions given to us it just states that the ripple should be 10%
     
  14. BillB3857

    AAC Fanatic!

    Feb 28, 2009
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    Google is your friend. http://www.reuk.co.uk/Making-Voltage-Doublers-and-Multipliers.htm is only one link. If you notice, many of the examples show transformer inputs, but your question indicates that you already have a 5v AC source. Simply apply it to one of the multiplier circuits. As for the amount of ripple allowed, capacitor sizing will have a large impact on that.
     
  15. Anosh89

    Thread Starter New Member

    Oct 29, 2011
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    I have succeeded in converting an AC to DC voltage. I don't know how to increase it from 5V ac to 8V dc.
    I do not know how to attach my circuit here in this discussion to show you.
     
  16. BillB3857

    AAC Fanatic!

    Feb 28, 2009
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    Did you look at the link I posted? Google has multiple listings for "Voltage Doubler". It will both convert AC to DC AND provide an output voltage that is greater than the input voltage. In fact, some sites carry the concept forward to "Voltage Multiplier.: These are frequently used in CRT televisions to help generate the high voltage needed by the picture tube.
     
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