74LS90 replacement

Ingo Debus debus at cityweb.de
Sun Mar 21 09:38:16 CET 1999


Plinio Andres Barraza wrote:
> Now that I got some things working on my bench, I wanted to build Tom's
> perfect vclfo with crossfade.  I have most of the chips I need, The only
> one I sould need to buy is the 74LS90, but I thought I'd check with you
> guys first because I got a bunch of chips that start with 74.. from a
> friend.  I'm not in front of them now but here are some of the numbers I
> remember:  74LS19 (could this chip be similar to the 74ls90 julst because
> it starts the same?),7450, 7474

Are you referring to Tom's staircase generator? The 74LS90 is used to
get 10 "stair steps". You can make one with four steps with a 7474 (of
course, the pinout of this IC differs from that of the 74LS90). If you
have two 7474, you can get eight or 16 steps. If you buy a new IC you
can also try the 74LS93, to get 16 steps with one IC.

Ingo




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