I need to build the following cicruit: F = (A AND B) OR (A XOR B) and I came up with the circuit in the image above. The bulb is only turning on when both A and B are OFF. The expected behavior is for the bulb to turn on if (A OR B).

I tested all the gates and bulb seperately and they all work as expected but the switch inputs don't, so I'm thinking it has something to do with the switch.

  • 4
    \$\begingroup\$ Draw the schematic. \$\endgroup\$
    – Andy aka
    Commented Nov 25, 2020 at 11:12
  • \$\begingroup\$ As Andy aka says, you should draw the circuit. If you draw a schematic diagram of the circuit from your wiring diagram, then I think you will see the problem. Trace out your circuit from the wiring diagram, and draw the schematic using individual logic gates rather than pins going into a box. It would also help us yo help you if you put a copy of the schematic in your question. \$\endgroup\$
    – JRE
    Commented Nov 25, 2020 at 11:53
  • \$\begingroup\$ On stack exchange sites, the solution of a problem is indicated not be editing the question, but rather by accepting (if necessary, first providing) a suitable answer. You have already accepted an answer, so your improper edit of the question has been rolled back. \$\endgroup\$ Commented Nov 25, 2020 at 20:32

1 Answer 1


I took a quick look at your Tinkerc cct.

Inputs to the 7486 XOR gate are both at logic 0 always. They are connected to GND. Output of the XOR will therefore always be 0 too. You need to connect the inputs to the upper side of the slide switch.


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