Mukhalled Posted April 13, 2007 Report Share Posted April 13, 2007 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 Quote Link to comment Share on other sites More sharing options...
AN920 Posted April 13, 2007 Report Share Posted April 13, 2007 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 Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 13, 2007 Report Share Posted April 13, 2007 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. Quote Link to comment Share on other sites More sharing options...
Mukhalled Posted April 17, 2007 Author Report Share Posted April 17, 2007 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 inputi 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. Quote Link to comment Share on other sites More sharing options...
Mukhalled Posted April 17, 2007 Author Report Share Posted April 17, 2007 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 ??? Quote Link to comment Share on other sites More sharing options...
AN920 Posted April 17, 2007 Report Share Posted April 17, 2007 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 Quote Link to comment Share on other sites More sharing options...
Mukhalled Posted April 17, 2007 Author Report Share Posted April 17, 2007 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 workingThanks 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 Quote Link to comment Share on other sites More sharing options...
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