I am fairly new to digital logic designing and I need some help in regards to finding a BCD to 7 segment decoder on software. I am using proteus for my counter, and for some reason I am unable to make it work. It either gives low and grey outputs only, no high output for my display. Any help would be appreciated.

i would like the chip to be like this, i have no clue on how to find the right one

Edit: i seemed to have missed posting the issue img. I have done so. What i want is like the black one. But in Proteus i am having issues.enter image description here

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    \$\begingroup\$ I don't know that software but your BCD = 0000, your decoder is giving outputs A to F and your display is showing 0 which is all correct. What's the problem? \$\endgroup\$
    – Transistor
    May 28 at 17:15
  • \$\begingroup\$ this seems indeed correct. @M4t1-1, I know this might seem obvious to you, but for us, with the information we have from your post, we can't see the problem. Can you very clearly say why what you're getting is not correct, and explain to us why it's incorrect? It might also be a good idea to show us more than one input value. \$\endgroup\$ May 28 at 17:16
  • \$\begingroup\$ Im sorry, i should be more consise, ill update another picture of my issue \$\endgroup\$
    – M4t1-1
    May 28 at 17:20
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    \$\begingroup\$ The 4055 isn't a BCD to 7-segment decoder, it's an LCD driver in addition to a BCD to 7-segment decoder. I'm not sure you can use it like this. \$\endgroup\$
    – Hearth
    May 28 at 17:31
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    \$\begingroup\$ I'm just wondering why you used different chips for each digit? Also you have overlapping ABCD wires which appear to short out the binary inputs as well as unnecessary crossovers. The outputs of U4 all appear to be shorted as well but pulling the upper display down one grid position should fix that. If you're interested in improving your schematics then have a read of Rules and guidelines for drawing good schematics on this site. It will help make the schema (design intent) more clear. \$\endgroup\$
    – Transistor
    May 28 at 18:06

1 Answer 1


That won't be very useful if the LED's cannot be driven from an LCD display and must be the correct polarity to match if low side segments or high (common cathode).

These designs are obsolete anyways and you can choose a better example to learn.

I'll post a link to an old discrete version of Binary to BCD decoder in comment. You can toggle the 1/0 and see the display change.


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