Yes another 555/4017 question. I'm teaching myself electronics with these two (so far) chips and lots of LEDs. As you know if you've been reading my threads here that I'm on a flashing LED kick and have had a couple of glitches along the way, like making the 555 and 4017 builds work right. I have discovered some thing along the way and would like to get some feedback on it if I can.
OK, this is what I've heard while researching flashing LEDs with a 555 chip. Most sources say you don't need to connect pin #5 of the 555 to any thing, not even ground. Then recently I heard that you might want to connect it to ground with a very low value capacitor to stabilize it, to protect the chip from outside interference. I tried that and it works, it solved a problem I was having with the 555 builds.
And now that I am connecting the 555 to a 4017 I was having problems, mainly a very random flash sequence. I just tried the same capacitor I used on the 555 build, a 107.2nf ceramic, on one of my two 555/4017 builds. I connected it to the #12 pin and it took most of the randomness out of it. And, because I wasn't satisfied, I just hooked one, a 23.33nf, up to the #5 pin of the 555 chip of this 555/4017 build and it completely took the randomness out of the flashing LEDs and there is a repeating pattern.
So to make a short story long, is there some good info on the web or personal experiences here about this problem and what to do about it? I think this is a major discovery that will help me with the rest of my builds/projects.
Moderator's Note : The title "Interference" is too narrow to figure out what's the problem, so I modified it to -- The Interference of NE555 and CD4017.
OK, this is what I've heard while researching flashing LEDs with a 555 chip. Most sources say you don't need to connect pin #5 of the 555 to any thing, not even ground. Then recently I heard that you might want to connect it to ground with a very low value capacitor to stabilize it, to protect the chip from outside interference. I tried that and it works, it solved a problem I was having with the 555 builds.
And now that I am connecting the 555 to a 4017 I was having problems, mainly a very random flash sequence. I just tried the same capacitor I used on the 555 build, a 107.2nf ceramic, on one of my two 555/4017 builds. I connected it to the #12 pin and it took most of the randomness out of it. And, because I wasn't satisfied, I just hooked one, a 23.33nf, up to the #5 pin of the 555 chip of this 555/4017 build and it completely took the randomness out of the flashing LEDs and there is a repeating pattern.
So to make a short story long, is there some good info on the web or personal experiences here about this problem and what to do about it? I think this is a major discovery that will help me with the rest of my builds/projects.
Moderator's Note : The title "Interference" is too narrow to figure out what's the problem, so I modified it to -- The Interference of NE555 and CD4017.