Re: Geared motor circuit
Firstly, TTL to CMOS replacements (NOT pin-to-pin):
7400 -> 4011
7474 -> 4013
74123 -> 4528
Nowadays you can get a small-footprint (reduced pins) microcontroller for well below $5, and some of these microcotrollers do not require special programmers; in fact, they can be programmed directly from PCs serial port (with level converters IC such as MAX202, MAX232 or similar) ..
Learning how to program them in assembly or C is not that difficult, so I think sooner or later you will "cross the floor" and try them ..
Regards,
IanP