Thanks Tkbits for your answer.
And NO, I don't have "just a wire between the collector and the reset pin with no pullup resistor". By the contrary, I have that "pull up" resistor in every transistor I connected in my circuit.
As you can see in my diagram the way how I've connected everything:
**broken link removed**
So you can see I have PULL UP resistors (1 Mohm).
**broken link removed**
I just wonder if there's no trouble in a circuit to have such big resistors in a transistor connection. As you can see, both Base and Collector, I have them with a value of 1 Mohm, because I don't need to Amplify anything, I just want the transistors to become a SWITCH (Low voltage or High voltage). Besides I thought of having the less battery consume. So, there would be only just some "micro Amperes" across this transistors, that really mattered only for managing VOLTAGE (because I have them to behave like an AND and NOT gate). And as I checked, they work good.
The strange thing is about those three IC555 that, if I use them connected the reset pin to this PULL UP resistor and collector, I only get them to work if I rapidly disconnect the wire from the reset pin (I've tried any other thing, as I mentioned previously, and only the disconnection of the reset pin wire is what works).
So, DO YOU KNOW OF ANY IC555 (FROM ANY MANUFACTURER) THAT HAS THIS KIND OF BEHAVIOUR ???
Cause I always thought IC555 where all the same, no matter what manufacturer.
By the way, thanks for the "Pull-up" explanation.
See you later !