relays

Discussion in 'General Electronics Chat' started by avi991, Feb 22, 2013.

  1. avi991

    Thread Starter New Member

    Feb 21, 2013
    2
    0
    how can we drive 100 relays with 40 digital I/O
     
  2. SPQR

    Member

    Nov 4, 2011
    379
    48
    One transistor per relay.
    Transistor relay pairs in a 4x25 network.
    25 digital pins to the 25 horizontal wires of the network.
    4 digital pins to the vertical wires of the network.
    One microcontroller
    A lot of time writing the program.
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,993
    3,229
    What determines the relay sequence?
     
  4. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Each pin drives one relay. Each realy drives one relay. Now you have 80 relays. 20 2nd tier drive a 3rd relay.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,974
    744
    Last edited: Feb 22, 2013
    Brownout and SPQR like this.
  6. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    ^-Awesome!
     
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