I have a S8050 with an Ib/Ic current gain of about 100. The diagram for the current gain in the datasheet shows Ic being 330mA at Ib 2mA for this transistor. In my circuit I drive a 3.3-5V motor with the transistor, both are fed from the same 4V source. The motor takes about 65mA when directly connected to a 4V battery pack. I measured the following values:
Provided current for base (with 2.2kOhm resistor): 1.8mA, measured current flowing to base: 0.2 mA, Ie = ~50mA
Provided current for base (with 1.0kOhm resistor): 4mA, measured current flowing to base: 0.22 mA, Ie = ~56mA
While I see a relation between the measured current flowing through Ib and Ie, I don't see it with the provided current for the base. In my understanding the motor should receive the full 65mA from the emitter as soon as I provide a minimum of around 0.5 mA to the base, which would lead to around 80mA for Ie (at least that's what the datasheet claims). But instead the measured current flow into Ib seems to stay static at around 0.2mA and Ie is smaller than expected (but still rising on higher input current values for Ib). Can anybody explain, why? Does transistors have a non-linear resistance on the base?