Help! Construct -12v Power Supply in NI Multisim

Discussion in 'The Projects Forum' started by jomico27, Oct 10, 2010.

  1. jomico27

    Thread Starter New Member

    Oct 10, 2010
    4
    0
    guys, i need to conctruct this -12v power supply in multisim..

    image attached in this post..

    please help me coz it is due on tuesday.. :(
    i need to have the output of its waveform using the oscilloscope..
    I'm using NI Multisim 11.. I've tried constructing this but I wasn't sure if
    i did it right..:confused:

    Here are the components:
    (1) 2.2, ¼-watt resistor (red-red-gold).
    (1) 10K, ¼-watt resistor (brown-black-orange).
    (1) .01µf (or larger) disc capacitor.
    (1) 10µf (or larger) 35 volt electrolytic capacitor.
    (1) 2200µf (or larger) 35 volt electrolytic capacitor.
    (2) Silicon Rectifier Diodes.
    (1) 1N4742A 12 volt Zener diode. From a two-pack available from Radio Shack.
    (1) PNP silicon power transistor. The TIP42 sold by Radio Shack is quite suitable here, and will be used as the example.
    (1) 2N3906 or 2N4126 PNP silicon transistor. Radio Shack sells a package of 15 PNP transistors that will perform well here, and provide transistors for experimental circuits as well.

    If you can do this in multisim, it'd be helpful if you post the screenshot of what you've done here.. :D

    here's the link of the complete detail of the power supply:
    http://www.play-hookey.com/analog/experiments/minus_12_volt_ps.html

    thanks in advance! :]
     
  2. jomico27

    Thread Starter New Member

    Oct 10, 2010
    4
    0
    I'm confused of what silicon rectifier diode I will use in multisim.. and also the -12v..:(
    My program is NI Multisim 11
    I've attached the image file of my work which I think is wrong:D
     
  3. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    The -12V in the play-hookey schematic is a label - it simply says that's the -12V output, it's a not a voltage source.

    I don't think the exact diodes you use matter, they're not even specified on your list of components. The 1N4001 should be fine.
     
  4. jomico27

    Thread Starter New Member

    Oct 10, 2010
    4
    0
    Is my construction in multisim of the schematic okay? or should i change/work on it again?
     
  5. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    Well there are two problems.

    One is that you need an AC source, your input is 12V DC.
    The second is your output capacitors. You have one that's 0.01 F. The original schematic almost certainly meant 0.01 uF, and that's confirmed by looking at the component list.
     
    jomico27 likes this.
  6. jomico27

    Thread Starter New Member

    Oct 10, 2010
    4
    0
    oh i see... thanks!
    i've changed them..

    is this okay? sorry, i'm a beginner..:)

    where should i put the positive and negative of the oscilloscope?
     
  7. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    I assume you want the negative to ground as that is the typical reference. You would place the positive on the point you wish to measure, like the output.
     
  8. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    If you want realistic results, you will need to load the output with a resistor from the output (-12V) to ground. To see the effect of the current limiting circuit (Q2 and R2), you will need to vary that load resistance. The current limiting will start to cut in when the load current reaches approximately Vbe2/R2≈0.6V/2.2Ω≈270mA.
     
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