Passive Ethernet Hub circuit question

Discussion in 'Computing and Networks' started by Tommy_cs, Jun 25, 2008.

  1. Tommy_cs

    Thread Starter New Member

    Sep 25, 2005
    3
    0
    Hi,

    I have found 1 interesting circuit on the web.

    http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm

    Do anyone know the function of diodes in the circuit?
    I just don't understand why the diodes are arranged in pairs, in opposite direction. So what is the diference if all diodes is removed?

    Thanks!

    :confused::confused:
     
  2. Tommy_cs

    Thread Starter New Member

    Sep 25, 2005
    3
    0
    Help!!! anyone have idea??:(
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    The only thing I can think of is a signal has to reach a certain threshold to be heard by the other computers. Personally I'm dubious, but if it works...
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    This is an example of Diode - Resistor Logic circuitry.

    http://en.wikipedia.org/wiki/Diode_logic

    The diodes are connected 'back to back' to respond to positive and negative going signals.

    Early computer logic circuits were constructed like this, with boards containing thousands of diodes.

    The same idea was later incorporated into integrated circuits as multiple emitter transistor gates in TTL.

    Hope this helps
     
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