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SCR and Diode are Active or Passive Components?

  1. Dec 9, 2011 #1

    SCR and Diode are Active or Passive Components?

    Please clarify the definition of Active and passive components. I have some confusion in it!
  2. jcsd
  3. Dec 9, 2011 #2
    A diode is a passive device - a non-linear passive device specifically.

    An SCR is an active device.

    An active device is able to take a signal and amplify or add energy to the signal. With an SCR, the applied gate signal voltage will turn on the SCR to pass current through, so it can pass more energy out than was put into it from the signal.

    A diode is passive because no matter what signal enters the anode, the diode will drop energy across it. One exception that a diode can be considered as an active device is when it is used as a switch, but even then I am not sure since the diode is not using any power source to do this switching.
    Last edited: Dec 9, 2011
  4. Dec 9, 2011 #3
    but i read somewhere on wikiuniversity.com that those components that supply power like battery etc are active components and those components that absorb or dissipate power.

    In SCR we basically control the triggering pulse so get desired power/output!
    it's mean if firing angle is 90deg then the output will be half. so SCR is not amplifying power
  5. Dec 9, 2011 #4
  6. Dec 9, 2011 #5
    You should do your own homework.
    Getting answers from sites like this does not do you any good and distracts from those that actually need help.
  7. Dec 12, 2011 #6


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    Staff: Mentor

    Diodes can be used as mixers, and oscillators, so I think they should sometimes be classified active devices. But as a rectifier, I guess it's a non-linear passive device.
  8. Dec 12, 2011 #7
    @Carl Pugh
    thanks you sir
  9. Dec 31, 2011 #8
    Active devices are energy sources and are capable of modifying or processing the signal.

    Both diode and SCR are active devices along with MOSFET and BJT and many others. You can tell an avtive device by looking at their I-V curve. They approximately look like current or voltage sources. BJT and MOSFET has I-V curve similar to a current source. Diode has I-V curve similar to a voltage source. While BJT and MOSFET can be used both as amplifiers or active load, diode can only be used as active load. Much the same goes for SCR. Interestingly, all semiconductor devices are active devices except semiconductor resistor ignoring its non-ideal behavior.
  10. Aug 7, 2012 #9
    thanks sir
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