Just a quick question on logic gates - in this case specifically on the diode. I've concluded for the following configurations of A and B (0,0 ; 0,1 ; 1,0) respectively \$V_{out}\$ returns 1, i.e. 5V because the circuit is open. Does the same apply for the case when both A and B have values 1 (meaning \$V_{out}\$ returns 1 too)?


I'm guessing it's the case since voltage in parallel circuits is the same and they do not sum up upon converging at the next branch.

  • \$\begingroup\$ Stuck the image inline for you. :) \$\endgroup\$ Commented Nov 28, 2012 at 21:18
  • 2
    \$\begingroup\$ If you label your components (e.g. D1, D2, D3, D4, R1) it will be easier to explain what's going on. \$\endgroup\$
    – The Photon
    Commented Nov 28, 2012 at 21:41

2 Answers 2


Because of the two diodes at the inputs, neither A nor B can pull the output low.

Therefore the output is always high.

Assuming the load on Vout is high-impedance, only if A or B were above 6 V or so would they have any effect on the output voltage. In that case they could pull the output above 5 V.


enter image description here enter image description here

One of these is OR logic and the other AND. Your circuit is neither.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.