74147N wont work - Getting no change in display

[Ironray]

Hello,

I have built a simple display circuit. I cannot get it to work.  I have tested each section of the schematic and they work except once the 74147 is connected.  

It seems as if the 74147 is not getting power.  Can anyone explain or help me get it working?

Thanks.

Ray

[yyao · Accepted solution]

Hi Ray,

I had a quick look at your circuit and I think you should add some pull ups to the input of the 74147. While this is most likely not necessary in a quiet environment in real life, it is good design practice to do so and avoid EMI problems down the road.

Attached is your modified circuit with 9 pull up resistors.

Hope that helps.

[Ironray]

Hey, thanks.  There was some discussion about using pull up resistors with my instructor.  He suggested 2.2KOhm resistors.

There is a lot to remember in Multisim.  

Thanks again.

Ray