Hello to everyone. I need some help and I don't find it anywhere.
I've using some 7490 IC for counting purposes, with a simple 555 circuit for clock pulses. Everything was fine.
Yesterday I had to replace one of the 7490 counter, so I used a 74LS90 instead, because I had no other. Surprise!! the counter didn't work!! and I changed no other thing.. I'm really confused..
Where the 7490 worked, this new 74LS90 doesn't... I tried everything in my breadboard but don't have any idea why this happends. The counter does not count correctly, and changes state not only in 1 to 0 clock transition, but also in 0 to 1. Counting seems random..
I tried 3 74LS90, and 3 7490; all 7490 worked, none of the 74LS90 did. I bought each one separately. Maybe the 74LS90's are defective??
I REALLY aprecite some help.
Greetings.
I've using some 7490 IC for counting purposes, with a simple 555 circuit for clock pulses. Everything was fine.
Yesterday I had to replace one of the 7490 counter, so I used a 74LS90 instead, because I had no other. Surprise!! the counter didn't work!! and I changed no other thing.. I'm really confused..
Where the 7490 worked, this new 74LS90 doesn't... I tried everything in my breadboard but don't have any idea why this happends. The counter does not count correctly, and changes state not only in 1 to 0 clock transition, but also in 0 to 1. Counting seems random..
I tried 3 74LS90, and 3 7490; all 7490 worked, none of the 74LS90 did. I bought each one separately. Maybe the 74LS90's are defective??
I REALLY aprecite some help.
Greetings.