7 Segment LED Counter, Need help!

[Mukhalled]

Hello,
I tried to simulate this circuit http://www.electronics-lab.com/projects/misc/012/index.html in Multisim, should pin 14 (count in) be connected to a 5V or GND or ...?

Can you help me please  ;D

 

[AN920]

Connect that to your input pulse you want to count. It won't count on its own. The count pulse must be a logic level input

 

[audioguru2]

Hi Mukhalled,
I haven't used old TTL ICs for many years and I have lost my TTL Cookbook.
The datasheet for the 74LS90 shows an inverting clock input pin 14, so I think it counts each time it goes low.

 

[Mukhalled]

Connect that to your input pulse you want to count. It won't count on its own. The count pulse must be a logic level input

i connect pin 14 to pulse generator (1Hz, 10Vp-p), but it doesn't count... i think there is something wrong in the circuit i connect in Multisim.

 

[Mukhalled]

Hi Mukhalled,
I haven't used old TTL ICs for many years and I have lost my TTL Cookbook.
The datasheet for the 74LS90 shows an inverting clock input pin 14, so I think it counts each time it goes low.

Yes, i think so too that it should count when it goes low. But it doesn't in the simulating program  ???

 

[AN920]

That part model (7447) in Multisim is known to be faulty over a few issues. Even in the latest release it is still not working. They never bothered to fix it. Use a 74HC4543 or 4543 to get it working

 

[Mukhalled]

That part model (7447) in Multisim is known to be faulty over a few issues. Even in the latest release it is still not working. They never bothered to fix it. Use a 74HC4543 or 4543 to get it working

Thanks to inform me about the 7447, i didn't find 4543 in multisim so i used 4511 instead (but changed the display to "commen cathode" instead) and finally it's working now ... Thanks again