HELP NEEDED. 7 segment LED display doesn't work

[ELT_Student]

The class as well as my teacher can not figure out how to activate the 7 segment LED in the mode 10 counter attached to this post. The attachment is the entire ckt from multisim version 10.1 (student).

I am at a loss :(.

[Fernando_D]

Hello,

Could you attach the Multisim file (*.ms10) for troubleshooting?

Regards,

[ELT_Student]

Thank you for pointing out that the attachent was not for multisim. The multisim ckt is attached to this post.

Thank you for the assistance and if you have any other questions, let me know.

Thanks,

Kevin

[Fernando_D]

Hi Kevin,

Here are some suggestions:

• Replace GND with DGND (digital ground).
• Replace the DC_POWER source with VCC (TTL supply).
• Go to Simulate>>Digital Simulation Settings and select Real. It will you better results.
• Locate component U4 (74LS47N) and connect pins ~LT, ~RBI and ~BI/RBO to VCC.
• Run the simulation.

Attached is your circuit with these modifications.

Hope this helps.

Fernando

[2910143]

i wolud realy appreciate if you could help me find what is wrong in this circuit!!

[digitalguy]

There are two basic problems with the ciecuit:

1- The display and the 74LS IC work with 5v

 2- Floating inputs on IC's are never good. When the switches on the 74LS47 are open, the IC's inputs are floating. The switched inputs need to be tied to +5 through pull up resistors.

See your circuit with the fixes attached.

[2910143]

can you upload this file using multisim 10??because i don't have mutisim 11!!

[2910143]

I have built a seven segment display circuit using nand gates.The i cannot get the Display to lit!!pleaaase help me!!(multisim 10.0)

[digitalguy]

Sorry, but I have no way to convert to Multisim 10. If you follow my written suggestions, you should be OK.

[2910143]

Hey i hVE an elecronics question,Which technology is better for the LCD technology TTL or CMOS??explain why??