Boost converter regulated output (fixed)

Discussion in 'General Electronics Chat' started by dante_clericuzzio, Jul 24, 2016.

  1. dante_clericuzzio

    Thread Starter Member

    Mar 28, 2016
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    adfdasf
    Zoom Pictures - 02016-25-24-08-25-02.jpg
     
    Last edited: Aug 1, 2016
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,969
    388
    Schematic please.
    What voltage/current is the light bulb.
    The LM2577 does regulate the output voltage so something is wrong.
     
  3. DickCappels

    Moderator

    Aug 21, 2008
    2,664
    634
    What are the values of your feedback resistors?

    And what, exactly are you using as an inductor (most likely culprit).
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,649
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    Hello,

    Wich version of the LM2577 are you using?
    There are the fixed and adjustable versions.

    Bertus
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    Is your 9V battery a PP3 type? If so, it will be limiting the input current and hence the output current.
     
    AlbertHall likes this.
  6. Papabravo

    Expert

    Feb 24, 2006
    10,167
    1,797
    Breadboarding a switching regulator is almost always a mistake. The capacitor cannot supply the current, or inductor cannot handle the current demand of a cold filament, or the source cannot supply at least twice the instantaneous current demand, that is most likely why the voltage drops.

    Your output power is 1.3 watts, so I estimate your input power requirement as 1.62 watts. At 9V this is .18 Amperes from the batteries. Are they capable of supplying that much power?
     
  7. Ylli

    New Member

    Nov 13, 2015
    26
    9
    Light bulb is 2.5 volt/0.35A? And you are connecting this to what is nominally a 14 volt output?

    The bulb is going to try to draw much more than 350 mA. And your input current is going to be almost 3x the current draw of the bulb. The AA batteries may not be able to supply sufficient current.

    When the output drops to 3.5 volts, what does the input voltage measure?
     
  8. crutschow

    Expert

    Mar 14, 2008
    13,054
    3,244
    Try the regulator with a fixed resistor load.
     
  9. DickCappels

    Moderator

    Aug 21, 2008
    2,664
    634
    Maybe the inductor has too much resistance, but we won't know unless that detail is posted.
     
  10. BobTPH

    Active Member

    Jun 5, 2013
    786
    114
    Measure it's resistance.

    You also must know the max current for the inductor. If exceeded it will saturate and not perform correctly.

    Bob
     
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