thank you for the capacitators advice.
well, i can get 2 to work, but then it gets messy and they all connect to each other because of the ground and 5v pin.
what i was thinking of doing was something like this (I hope i did not make any mistake, i did it with the breadboard view, and then exported the scheme):
all the sensors end up connected because they share 2 pins. ir sensor and piezo had no problems, but when i try connecting the ldr, one of the others starts misbehaving. my goal is to connect 3 ldr, 1 ir sensor, and 1 piezo.
EDIT: So, after some research and testing, i have concluded that i seriously need those capacitators. with an ldr and the piezo connected, even if the piezo is connected to the analog pin, the ldr still accounts for 95% of the variation. will 0.1 uf be enough?
I was also advised to use 4.7 on the piezo, but if the ldr is the one changing the value, then my piezo doesnt really create that much tension change, right? (I dont have a multimeter to check it out).
I guess for now, thats my problem. Huge, huge interference between sensors, which i hope is the "noise" and will be solved with the capacitators