Lowering V, Raising I

Discussion in 'General Electronics Chat' started by iONic, Jun 3, 2011.

  1. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    The ideal scenario is to take aprox 12 - 18V DC at about 800mA and convert it to a fixed 3V with a potential current of 3A.

    Is this possible? What would you suggest is the simplest way to make this?

    Thanks
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. jegues

    Well-Known Member

    Sep 13, 2010
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    bertus seems to have linked an IC that could very well get the job done, but just for the heck of it I'll throw something out there.

    I could be completely wrong, but here it goes!:D

    Couldn't you feed your signal into a zener regulator, followed by a emitter follower?

    The zener should handle the voltage regulation, giving you a stable 3V while the emitter follower provides you with the current gain needed to pump the signal up to 3A. You might have to tweak the voltage across the zener to give ~3.7V, because if you are taking your output across the emitter terminal you will lose some voltage(~0.7V) across the BEJ.

    I'd love to hear what others (perhaps more knowledgable on the subject) have to say about this idea.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    @ jegues,
    The circuit you propose will have an input current equal to the output current.
    The voltage difference X output current will be dissipated as heat.
    The efficiency is very low.

    Bertus
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    12v @ 800mA is 9.6 Watts; 3V @ 3A is 9 Watts, so you would need a DC-DC converter that is 93.75% efficient or better. That is possible, but it's not exactly simple.

    You will need to do a good bit of research on SMPS's (switch mode power supplies).
    I've attached a couple of PDFs that will give you a brief intro.

    You can do a lot of reading on http://www.smps.us
     
  6. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    Thanks guys. This should get me started...with a great many more questions, but I will try to sort it out somewhat myself.
     
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