I made a 0 to 99 counter. When I just had 0 to 9, it counted correctly. Once I added
the tens digit, it started to count from 8, then it counted correctly up to 99 and started
over at 0. Not sure where I have gone wrong. Here is the schematic. Thanks in advance.

 

Once I added
the tens digit, it started to count from 8, then it counted correctly up to 99 and started
over at 0. Not sure where I have gone wrong.

That sounds like reasonable behavior to me. If you want the counter to power up in a certain state, you need to add a power on reset.

 

That sounds like reasonable behavior to me. If you want the counter to power up in a certain state, you need to add a power on reset.

Done! Works!

 

I just commented on another thread with the same counter drawing.