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3V to 5V dc-dc boost converter

  1. Jul 26, 2004 #1
    hi everyone :smile:

    i am a 2nd year engineering student....i have a problem here... :confused: i was asked to build a 3V to 5V dc-dc boost converter but i have no idea how to build it... i have search all over the webs but the information they gave me ain't what i want.

    i was asked to build a step up from 3V to 5V converter using only discreet components. I can't uses switches too... :frown: The current must be within 30mA.

    I would appreciate it very much if anyone can help me... :wink:

    Thankz :biggrin:
  2. jcsd
  3. Jul 27, 2004 #2
    Take a 3V battery and connect a 2V battery in series.
  4. Jul 27, 2004 #3
    i can only use two 1.6V batteries in the circuit.
  5. Jul 27, 2004 #4
  6. Jul 27, 2004 #5
    hehe... i've tried building this circuit already but don't know why it can't work.
    is it because of the values i use for the components?
    i've used:
    1)150uH inductor
    2)BC817-25 transistor
    3)0.47uF cap
    4)BAS85 diode

    can give suggestions on what components i can use?
    Thanz =)
  7. Jul 27, 2004 #6
    Got me there. My experience consists in building a capacitive discharge ignition system from a kit forty years ago that had a 12 to 400V dc-dc converter in it. Put out a hell of a spark--actually advanced the timing.
  8. Jul 27, 2004 #7
    Then how can i calculate the values of the components i need to boost the voltage from 3V to 5V??
  9. Jul 27, 2004 #8


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    Science Advisor

    Are you certain your timing circuit is sending pulses to the transistor that saturate it?

    How much of a load are you placing across the outputs of the boost converter?

    What does the behavior across the components look like on a scope?

  10. Jun 10, 2007 #9
    try this i requires no inductors

    I was searching for a single component to do this and ran across your request.
    Try the attached circuit. It is an astable multivibrator tied to a voltage doubler.
    It's very straight forward.
  11. Jun 10, 2007 #10


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    Gold Member

    This thread is going to be 3 years old soon.

    BTW, you forgot to attach the circuit for those who may interested in it.
  12. Jan 12, 2008 #11
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