correction

Discussion in 'Feedback and Suggestions' started by Unregistered, Jul 14, 2009.

  1. Unregistered

    Thread Starter Guest

    in the web page http://www.allaboutcircuits.com/vol_3/chpt_1/2.html which discusses "Active versus Passive Devices" the definition for Passive Devices is given:
    Components incapable of controlling current by means of another electrical signal are called passive devices.
    But,it should be,
    Components incapable of controlling current by themselves but can do so by means of another electrical signal are called passive devices
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    I believe the first definition is correct. By the name. a passive device does not has any external means of controlling/affecting electrical signals applied to them.

    If a control signal can be applied, then the device is no longer passive. Think of a resistor versus a transistor.
     
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Almost all active devices exhibit some degree of non-linearity, as well. A diode, for instance, is capable of mixing (modulating) signals.

    The status of a diode as an active device seems to be in taxonomic limbo. I'm comfy with it either way.. :)

    eric
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    Narrow definitions seem to have minefields attached. Perhaps we need a category of "really passive devices" and then "almost passive devices".

    If you have the right devices in mind, the distinction is obvious. But how do you categorize carbon granules or quartz crystals? A simple dichotomy becomes confusing due to exceptions.
     
  5. RiJoRI

    Well-Known Member

    Aug 15, 2007
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    So, we'll have "impassive devices", "passive devices", "lazy devices", "active devices", "hyperactive devices", and "bouncing-off-the-walls devices"?? ;)

    --Rich
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    Diodes can switch, they can oscillate under certain conditions (not all diodes, but some). A resistor, capacitor, and inductor sit there and passively react to their environment.

    I wouldn't call a relay active, but it does some of the same things. I think the differentiation would be it is electromechanical, just like other devices are pneumatic.

    Sounds like a transistor to me.
     
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