ttl ic`s

HC are CMOS with different logic levels and loading capabilities. They are proably easier to obtain nowadays than standard TTL.

RL

From the subject header, I figured the post would be about some old schematic that used straight TTL, while the poster wanted to use more recent variants.

I still have some straight TTL around, but that's because when I started with the 74XX family, TTL was the norm, with "H" and "S" sort of there. I'm surprised that someone would have TTL and nothing more recent lying about.

Michael

On another net group A.B.S.E. the OP has changed his TTL to LS TTL, with the same basic question.

I think the answer is the same, unless he chages the CMOS end of the equation to AC or AHC - and even then some precautions are needed.

RL