4 bit relay computer

This is my first 4 bit adder built with nothing more than relays.



The forest of wires on the right are used to set the input values (in the picture Input1 = 0100 (4 in base 10) and Input2 = 0101 (5 in base 10)), and the LEDs on the left are used as output indicators for the SUM (in this picture 1001 (9 in base 10)).


  1. written by: John on May 31, 2014 at 1:20 am - Reply

    do you have a schematic for your 4 bit relay computer you could e-mail me?


    • written by: Mihai on June 1, 2014 at 10:47 pm - Reply

      I’ve included a schematic in the above article.

  2. written by: John on May 31, 2014 at 1:21 am - Reply

    Great work.

  3. written by: Joseph on September 11, 2021 at 9:24 pm - Reply

    Thank you for breaking it down like this on how it wired. ive been looking on how to build a 4 bit relay adder.

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