Parallel Binary Adder w/ Dual Seven seg display

[sid_j]

Hi. I'm trying to create a 4 by 4 binary adder in which the output gets converted from binary to decimal through a BCD (7447) decoder, and is shown on one dual-seven segment display. The part which I don't get is how to display the correct output on the "dual" seven seg, meaning showing the correct tens digit. I would be very thankful if you could help me out (I'm new to this stuff :cry: ).

 

[Russlk]

You need to multiplex the 7447 outputs. Take a look at MC14553b, the data sheet shows how it is done.

 

[sid_j]

sorry, I don't understand that figure. I don't have many items available > except for a 7447, a dual 7 segment display.

I have attached my schematic. The part which I don't understand is for example when I add 8 + 1 + 1, how do I get "1" and "0" on the dual seven segment.

 

[Russlk]

The BCD adder can only add to 9 so there is no need for the second digit. You need a two digit adder circuit. I don't know how to do that, but perhaps someone can tell you.

The alternative is to treat the adder as a binary adder then do a binary to BCD conversion.

 

[sid_j]

Ok Thanks. That helps a bit. hmm the bcd can't handle a number more than 9. do you know the name of the two digit decoder?

I don't know if I understood the alternative way. Perhaps if you can attach a schematic, that would be just great. I just need to know how to add a tens digit display using another seven segment.

 

[Nigel Goodwin]

Have you tried asking your teacher/instructor?, I'm presuming it's a school project and NOT a practical requirement?. Other wise simply use a micro-controller, after all this is the 21st century.