PoE, RJ45, SD card and op amp

Using Arduino Networking, Protocols, and Devices
1

Hello everyone.
I have many questions.
First, What is the difference between PoE IEEE802.3af and RJ 45?
Is it okay to use RJ45?
I want to make sending email system by using ethernet shield.
And what is the purpose of sd card?
Do you think i need sd card?
Finally, I want to amplify the input signal.
Because my input is micro voltage.
So I am going to use op amp but i have no idea about this one.
Is it okay to use op amp and How to connect the op amp to arduino?
Thank you for reading my question.
I will wait your genius.

2

pokipoki:
Hello everyone.
I have many questions.
First, What is the difference between PoE IEEE802.3af and RJ 45?
Is it okay to use RJ45?

You must use the RJ45 socket for PoE (Power over Ethernet). There are two types of PoE units. Insure the PoE unit does not use the data lines to supply power.

pokipoki:
I want to make sending email system by using ethernet shield.
And what is the purpose of sd card?
Do you think i need sd card?

Need? No.
Helpful if you want more memory than the Arduino has? Yes.

pokipoki:
Finally, I want to amplify the input signal.
Because my input is micro voltage.
So I am going to use op amp but i have no idea about this one.
Is it okay to use op amp and How to connect the op amp to arduino?

Yes, it is ok. Connect the output of the op-amp to one of the analog inputs. When considering the amplifier's gain, insure the output voltage does not exceed the rating for the Arduino's analog input. Best way to insure this is power the op-amp with a supply voltage at or below the rating.

3

Thank you for answer!!
I have three questions.

  1. If I use the RJ45 cable for connecting internet for sending email, should I use another PoE such as IEEE802.3af?
  2. Is thermocouple output voltage analog?
  3. How to connect the op amp to the arduino?
    My arduino is UNO.
    Please help me again genius!!
4

You don't need PoE. I don't use it.

Normally a thermocouple is an analog output.

Do a Google search for op-amp circuits. You will probably need a non-inverting amplifier circuit.

5

I really want to say thank you for your answer.
Have a good day genius~

6