7447 7 Segment Display Circuit - 3-9 show up correct but 0-2 is not.

Thread Starter

IcyCold44

Joined Oct 18, 2023
2
Hi,

I have this lab assignment I'm trying to complete in Proteus. Our university from in person labs to online, which I really hate as I love building circuits in person, but I have to deal with it. The picture attached is my circuit. The pull down resistors are 1k while the current limiting resistors are 220. I am not sure if it's an issue with the circuit I've made or I just don't understand the software that well.
 

Attachments

sarahMCML

Joined May 11, 2019
392
Are you sure that you haven't got your pins mixed up between the switch and the 7447 inputs? If you're using the pin numbering of the switch then they are wrong!
 

dl324

Joined Mar 30, 2015
16,990
Welcome to AAC!
I am not sure if it's an issue with the circuit I've made or I just don't understand the software that well.
For those of us not familiar with Proteus, does the black on the DIP switch indicate the option that's selected? What does yellow mean on the nets? Unknown state?

With all lows on the decoder inputs, all of the outputs except 'g' should be low. Is there a reason why the 7-segment display isn't reflecting what's on the outputs of the decoder?

It would be helpful if you cleaned up the routing.

Remove unnecessary wire bends, backtracks, and connection dots so we can see how things are actually connected.

If you rotated the resistors on the decoder inputs 90 degrees, you could get them out of the way so you don't have to jog wires around them.
 

MrChips

Joined Oct 2, 2009
30,931
Agreed.
Connect the DIP switch straight across to the 7447 decoder. Place the pull-down resistors going downwards to GND.
Put Vcc above everything else. It is customary to put Vcc above and GND below.
 

Thread Starter

IcyCold44

Joined Oct 18, 2023
2
I recreated the circuit as requested. It seems to work fine now!

For those of us not familiar with Proteus, does the black on the DIP switch indicate the option that's selected? What does yellow mean on the nets? Unknown state?
I wasn't sure at first either, but I believe the black indicates the position.
 

Attachments

dl324

Joined Mar 30, 2015
16,990
I recreated the circuit as requested. It seems to work fine now!
My guess would be that you had a connection error that was obscured by the messy routing and unnecessary connection dots. Neatness does matter. For us when we're trying to read a schematic and you when you're trying to troubleshoot a circuit that isn't working.

If you make the pull-down resistor orientation vertical, several wire bends would become unnecessary.

In general, we prefer for schematics to be monochromatic. You can get that from Proteus by printing to PDF and posting a clip. That also eliminates the useless grid.
 
Top