[time-nuts] Subs for obsolete chips in pictic

Hal Murray hmurray at megapathdsl.net
Mon Dec 12 04:53:20 EST 2011

> Better use 74HC or 74HCT parts, the 74F should be TTL FAST parts that
> require high input current to be driven correctly. 

HC/HCT are pretty slow.  I'd carefully check the data sheet timings before 
substituting for AC.

Yes, F/FAST requires some input current, but I wouldn't call it "high".  It's 
higher than CMOS but might work in some cases.  Again, check the data sheets. 
 (Or try it for a low volume project.)

These are my opinions, not necessarily my employer's.  I hate spam.

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