I came here to ask about calculating the BASE current for a PN2222 transistor. After using the search function, I discovered this thread on a similar topic. I opened up the datasheet and found the information I was looking for (the BASE peak current) but then I starting wondering how much variance there is between makers of these parts. For example I bought from a local electronic store and the description on the part is:

Code:

`2N2222 Bipolar (BJT) Transistor NPN 30V 600mA 250MHz 625mW Through Hole TO-92-3`

One additional question, what I am really trying to understand is why various sources on the internet use anything from 470 ohm resistor to 10K ohm resistor on the base. It seems completely random to me. I found this youtube video which seems to explain this.

He says that you look at the peak current on the base and then test like this

I = V/R

Assuming a 9V battery, a drop of 0.6V and a 100Ohm resistor the math would be

I = 8.4/100 = 84mA

This implies that 100Ohm should be fine. This brings me back to the "random" examples on the internet with such a wide variance in resistors for the base of this transistor

TL;DR

Are datasheets specific to the manufacturer of a given generic component like a 2N2222?

If not how do you identify the correct datasheet?

Specifically for the 2N2222 transistor, what is the proper way to determine the resistor for the BASE?