Dear fellows,
This is my fisrt post.... not from lack of reading posts, but needed some sort of confirmation from you the seniors.... 
I've different type of industrial sensors, mainly photo electrics proximity sensors....
they are using different DC voltage: 5-24 V DC; 3.3V dc..
since I'll be using 12Vdc motors in my project using an Arduino UNO,, My power supply will be @12 Vdc, which I tested out all good.. including the sensors that triggers and commands/ program works perfectly under 12V DC.
Now, I would like to add an optical sensors which uses IR emt and Recv. they are running at 3.3VDC Max.
i know , I have a dedicated 3.3 VCC on the UNO, but If I use that pin as my source of power, when I assign an Pin for input (the sig from my sensor), would it be taken and detect the HIGH and LOW?
again, I have my 90% of answer, but needed to see if I get confirmation from here...
Thanks a lot for sharing your experience here and taking the time to read my long post!!!
Thanks and have a great Thanksgiving if you are in Canada!!!
Cheers
Bob