Output will be '1' if only two out of three inputs are '1'.

Moderators note: reduced font and removed bold, as it would be like shouting

 

Use three 2-input AND gates to detect each input pair being both 1. Use a 3-input OR gate to see if the output of any of the AND gates is 1. If the three inputs are A, B, C, then the Boolean expression is

AB + AC + BC, which will be 1 if any pair of inputs is 1

 

Use three 2-input AND gates to detect each input pair being both 1. Use a 3-input OR gate to see if the output of any of the AND gates is 1. If the three inputs are A, B, C, then the Boolean expression is

AB + AC + BC, which will be 1 if any pair of inputs is 1

But it will also be 1 if all three inputs are 1, which contradicts the stated goal of having the output be 1 if only two out of three inputs are a 1. But this could be just a case of sloppiness on the TS's part, particularly since it would probably be better stated as wanting a 1 only if two of the three inputs are a 1.

@Sebastian Lee: Did you mean exactly two of three, or at least two of three?

If the latter, the circuit is called a "majority detector" or sometimes a "voting circuit".

If you meant the former, then it is almost an even parity detector (which would be a 1 if either exactly zero inputs were 1 or if exactly two inputs are 1. It could be implemented pretty easily starting with either a majority detector or an even parity detector.

 

Hello,

@WBahn
When it is exact two, it could be an even parity circuit, as it has only 3 bits.

Bertus

 

Hello,

@WBahn
When it is exact two, it could be an even parity circuit, as it has only 3 bits.

Bertus

So what is the output of an even-parity circuit when all of the inputs are zero?

 

Hello,

Ai, I see. with all zeros it will also be 1.

Bertus

 

And a bunch of nots.

 

#7 is the winner.

ak

 

#7 is the winner.

ak

That's IF the TS meant exactly two of the three. There's no way to be sure unless the TS clarifies what the spec is.

 

I think "exactly" = "only."

ak