Will this transistor/ relay set-up work?

Using Arduino Project Guidance
4

Grumpy_Mike:
You need a 125R resistor between the pin 5 and the gate of the FET.
You need a reverse bias diode across the relay.
You need to connect the -ve of the battery to the arduino ground.

  1. How did you calculate the size of the resistor and why is it needed exactly.
  2. Do I need a reverse bias diode because of how the transistor is wired to the relay?
  3. I did the sketch pretty fast, I will ground the Arduino to the battery and make a 5v regulator for the (+)

I'm just starting to get into this stuff so go slow :smiley:

Thanks so much,

Andrew

tigerbomb8:
what are you trying to do?

Use an RFID reader to act as my ignition switch (or kill switch), since I have no key.
I guess I could use a smaller Relay, I just have this one laying around.