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[ECEkid]

Hi Tayyab,

When I replace your global VCC and GND with the DC source, the simulation from your citcuit work fine.  The problem happen when I have another 74F14D which have the VCC is at 5V and GND is at 0V as shown in the attached Multisim circuit.

[ECEkid]

Please use the following circuit.  I do not know why the attached circuit from previous E-mail hidden pins doe not retain the value assign.

Thanks,

D. Nguyen

[Tayyab_R]

Hi Mr. Nguyen,

The main issue is that you need to place a VCC and a Digital Ground on the schematic. The hidden pins need these sources to be placed on the design atleast once so they can connect to them. There is a difference between Digital Ground and Analog ground. You need to place the DGND from the sources as well. I have made the modification to the circuit and now it seems correct.

Hope this helps.

[ECEkid]

Hi Tayyab,

The application tip is great.  All of previous posts are the simplify duplicates for the issue.  All simulation problem is from the followingcircuit.  Both of U11B and U12C inputs are O.K.  The output are stuck at low at high. 

Thanks in advance for your help,

D. Nguyen