Multisim and BCD Display issue

**dbeckfor** · Nov27-09, 11:36 AM

I can not figure out how to get my 7 segment BCD display to turn on in Multisim. I am using the 74LS48N Decoder and the Common Cathode 7 Segment Display. I have attached a view for it,its a little messy.

**berkeman** · Nov27-09, 11:58 AM

Originally Posted by dbeckfor

I can not figure out how to get my 7 segment BCD display to turn on in Multisim. I am using the 74LS48N Decoder and the Common Cathode 7 Segment Display. I have attached a view for it,its a little messy.

What do you see when you monitor the currents in various parts of the LED drive circuit?

**dbeckfor** · Nov27-09, 01:16 PM

Originally Posted by berkeman

What do you see when you monitor the currents in various parts of the LED drive circuit?

I get 3.32 pA and 3.32 mV

**berkeman** · Nov28-09, 12:48 AM

Originally Posted by dbeckfor

I get 3.32 pA and 3.32 mV

Well, pA will not light an LED. Are the signals going into your LED driver correct? That's the advantage of a simulator (or an oscilloscope on a circuit) -- trace the signals out...