Electronic – Why does this 7-Segment Display not function properly

7segmentdisplaydecoderdigital-logicdisplayintegrated-circuit

I've provided details in image.

Although, I'll once again provide in text:

IC : 74LS47N (Binary to 7-Seg Display)

7 Segment : Common Anode

M.S.B : D

L.S.B : A

This is how absurd OUTPUT is displayed by 7-Seg Disp:

INPUT (D,C,B,A to IC)___OUTPUT (7-SEG DISP)

DCBA

0000_______________2

0001_______________3

0010_______________2

0011_______________3

0100_______________b

0101_______________7

0110_______________b

0111_______________7

1000_______________c

1001_______________ɔ <— (-_- !) lol

enter image description here

I've edited the pics, so that you may see the wirings clearly.
As you can see the problem in the image itself,(i.e. the output of 7-Seg does not matches with the input to the IC).

Note: There is no problem with my connections. They are exactly as shown below:

I did the connections 5 to 6 times all over again, but all it shows is absurd and illogical results

enter image description here

Best Answer

The 74LS47 shows the following: $$ \begin{array}{ccccl} D & C & B & A \\ 0 & 0 & 0 & 0 & \rightarrow 0 \\ 0 & 0 & 0 & 1 & \rightarrow 1 \\ 0 & 0 & 1 & 0 & \rightarrow 2 \\ 0 & 0 & 1 & 1 & \rightarrow 3 \\ 0 & 1 & 0 & 0 & \rightarrow 4 \\ 0 & 1 & 0 & 1 & \rightarrow 5 \\ 0 & 1 & 1 & 0 & \rightarrow 6 \\ 0 & 1 & 1 & 1 & \rightarrow 7 \\ 1 & 0 & 0 & 0 & \rightarrow 8 \\ 1 & 0 & 0 & 1 & \rightarrow 9 \\ 1 & 0 & 1 & 0 & \rightarrow c \\ 1 & 0 & 1 & 1 & \rightarrow ɔ \\ 1 & 1 & 0 & 0 & \rightarrow u \\ 1 & 1 & 0 & 1 & \rightarrow 3~horizontal~lines \\ 1 & 1 & 1 & 0 & \rightarrow broken~6 \\ 1 & 1 & 1 & 1 & \rightarrow \end{array} $$

You show:

$$ \begin{array}{ccccl} D & C & B & A \\ 0 & 0 & 0 & 0 & \rightarrow 2 \\ 0 & 0 & 0 & 1 & \rightarrow 3 \\ 0 & 0 & 1 & 0 & \rightarrow 2 \\ 0 & 0 & 1 & 1 & \rightarrow 3 \\ 0 & 1 & 0 & 0 & \rightarrow b \\ 0 & 1 & 0 & 1 & \rightarrow 7 \\ 0 & 1 & 1 & 0 & \rightarrow b \\ 0 & 1 & 1 & 1 & \rightarrow 7 \\ 1 & 0 & 0 & 0 & \rightarrow c \\ 1 & 0 & 0 & 1 & \rightarrow ɔ \end{array} $$

This makes me think your B term is hard-coded to a 1 and that you are misinterpreting a 6 as a b.

Check your B term going into the 74LS47. If it is working, then I think your 74LS47 has a damaged B input.

EDIT: Good to hear that you got it working!