Looking to use a relay with ardiuno but having a hard time trying to figure out what transistor I need to use, all the tutorials I can find always use an example transistor (usually 2N2222) to figure out what resistor to use, but not how to select a proper transistor in the first place. Once I have a transistor that is properly suited then I should be able to use those previous guides to figure out what resistor I need for arduino.
Can anyone enlighten me on how I should go about selecting the proper one for my needs? You're more than welcome to tell me what would work (properly suited not overkill) but I'd also like to know how to figure this out for future projects.
Note: The relay will be powered by a separate power source and not from arduino. Relay is not going to be located on or near the circuit board (remotely mounted) hence choosing a relay with a built in flyback diode.
Coil resistance: 123 Ohms, Coil Current: 97.5 mA https://www.mouser.com/datasheet/2/378/301-2555.pdf