PLs Help.. What is a amplified diode circuit

Discussion in 'Homework Help' started by coach tronix, Jul 31, 2008.

  1. coach tronix

    Thread Starter New Member

    Jul 31, 2008
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    do you know anything about the Amplified Diode circuit also known as the adjustable zener diode or the VBE Multiplier..

    your help will be appreciated... tnx
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Can't show you a diagram at the moment, but if you connect the top and bottom (track ends) of a potentiometer to the collector and emitter of a transistor. Also connect the slider to the base. Place terminals on the collector and emitter.

    You have a two terminal device, the voltage across which depends upon the position of the slider.

    It is used to provide bias compensation in audio amplifiers amongst other things as the voltage range is greater than a standard diode.
     
  3. coach tronix

    Thread Starter New Member

    Jul 31, 2008
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    tnx 4 that.. just got a schematic of the amplified diode right now.. it's like what you described.. tnx a lot..


    a amplified diode circuit has a greater range than a normal zener diode right? and aside from that, what are the other advantages of a amplified diode circuit compare to a normal zener diodes? and Why?


    sorry, if i have so many questions.. i just cant figure out the logic of the amplified diode circuit in our class..


    tnx 4 ur time..:)
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    An amplified diode has a negative temperature coefficient. Then its voltage drops as it gets hotter. It is used to regulate the current in the output transistors of an audio amplifier.

    An amplified diode's voltage increases as its current increases and its voltage decreases as its current decreases. It has poor voltage regulation.

    A 5.6V to 6.8V zener diode is temperature stable and its voltage changes only a little when its current changes.
     
  5. coach tronix

    Thread Starter New Member

    Jul 31, 2008
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    thanks for that info Audioguru... that will help me a lot..
    i appreciated your help!! thanks!!
     
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
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    A normal zener diode has a fixed voltage.

    The amplified diode has a (finely) adjustable voltage. Thisa can be useful if you want some exact figure to setup an amp to minimise distortion

    Over to you Guru.
     
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