jbilander
commented
2 years ago Hi, you are probably just fine with 74LS. 74HCT is actually a good replacement for old 74LS that is becoming more or less obsolete these days. Both are TTL logic levels which is good because the Amiga is TTL and also the RGB HV-sync and C-sync are 5V-TTL. The Schmitt-Trigger (ST) helps with jitter clean-up and slow edges. I think your 74LS14 has ST on the inputs too, so you are probably just fine with using that chip. So to answer the question: Yes it's important to choose a logic family that is TTL-compatible. It will probably work with for example HC which is CMOS-levels but why go down that route when HCTs are available.
You can read about some LS vs. HC(T) differences here: https://electronics.stackexchange.com/questions/358620/74ls-vs-74hc-series-ics-for-ben-eaters-8-bit-computer
Regards, J
How critical is the logic family used in the Amiga db23 to VGA adapter? I had an 74LS14, not 74HCT14, and made this adapter. It works but I wonder if the logic family choice is critical to prevent any jitter. Monitor used: Dell 2001FP 20" LCD, which has the ability to sync down to 15 kHz line frequency.