Hy,

I try to simulate a decimal to binary encoder on Multisim but it doesn’t work.

I first did the truth table with the four output named A3(MSB), A2, A1, A0 so I get the funtions :

A0 = 1 + 3 + 5 + 7 + 9

A1 = 2 + 3 + 6 + 7

A2 = 4 + 5 + 6 + 7

A3 = 8 + 9

I put 4 leds after the 4 output to count in binary. When I press 1 it lights 1 so ok, 2 > nothing, 3 > 1 so not ok, 4 > 4 ok, 5 > 5 ok, 6 > 4 not ok, 7 > 5 not ok, 8 > 8 ok, 9 > 9 ok

Can you see the problem ?

 

You have a break between A1 and R3.

 

Can you examine the pattern of your actual outputs compared to your expected outputs and determine a very simple description of how your circuit is misbehaving?

Then perhaps examine that portion of your circuit and see if there is something simple and obvious in your connections that might be causing the problem?

 

Thanks to both ou you, indeed there is a break between A1 and R3, it works fine now!