I know this question was asked before, But couldn't understand properly the datasheet reading.

I would like to control water pump via RPI.

Wanted to make sure Im reading the datasheet correctly + Im connecting everything properly.

So if I understand correctly, on the worst case, the water pump will need 6v. so the calculations will be according to Ipump(max)

Ipump(max) = 1.8w/6v = 300mA
Ipump(min) = 0.6w/4v = 150mA


According to 2N2222 data sheet, figure 11:

When Ic=300mA, Vbe(sat)=0.9v and hfe=10.

So:

Ib = Ic/hfe -> 300m/10 = 30mA
R1 = (Vrpi - Vbe)/Ib -> (3.3-0.9)/30m = 80ohm


In order to make sure the water pump will get the current it needs, we will limit Ic to higher value:

R1=50ohm
Ib=(3.3-0.9)/50= 48mA
Ic=Ib*hfe= 48m*10 = 480mA


So R1=50ohm

1. Do I read the hfe correctly? is it the right value to make sure the saturation?