I struggle to understand to relationship of Ic and Vce. I have the following circuit: A voltage supply at 12.4V, a LED with 0.2A current 9V, a BJT with the Ic-Vce relation shown in the picture below and a resistor to ground.
As far is I understood and measured, the LED can be considered a constant current source.
The strange behavior I do not understand is the following: If i increase the supply voltage by 1V to 13.4V, the LED's voltage remains the same, so does the voltage over the resistor. Thus the current mus still be the same, 0.2A. I measured an increase by 1V over the transistor, jumping from 1.4 to 2.4. If i now examine the Ic - Vce graph, I cannot understand why the current doesn't change.
I would be really glad, if someone could enlighten me.