my 3-bit counter is supposed to count 2,7,1,6,3,0 infinately, in binary of course (output via lightbulbs for now) - there's a silly problem and I can't work out why - the circuit half works in that it counts 2,0,1,6,3,0 (then repeats) i.e the 2nd output is a 0 instead of a 7, I've check and rechecked all my equations and k-maps, I can't see anything wrong?

(Also must apologise for the awful layout, it should be a lot easier to follow than that - but we all have to start somewhere )

Attached Images

3-bit_counter.jpg (25.6 KB, 189 views)

 

Also, whilst I've got your attention - how could I go about converting a 3 input AND and OR gate into a NAND gate (combo)? Is it just a case of putting 2 in serial? Can do 2 inputs easy enough...

 

Well I've worked out the answer to my second question now, but still puzzling over the circuit issue...