I'm doing an experiment while reading the self-study book by Kybett "electronics self teaching guide" In the experiment I measure the current to the base and collector of a NPN transistor then observe that the ratio is basically constant and consistent with the manufacturer's specs.
But my ratio isn't constant. In addition I'm having trouble locating "beta" , the ratio on the datasheet. I see one mention of "beta=10" this is nothing like any of the values from my test.
Here are my data. What am I missing?
Rb=base resistance Vc=base collector voltage Ib= current base Ic=current collector
Rb Vc Ib Ic Ic/Ib 1Mohms 6.89 V 8microA 1.51mA 189 690kohms 6.25 V 12microA 2.17mA 197 470kohms 5.24 V 17microA 3.20mA 188 220kohms 1.89 V 36microA 6.57mA 182 194kohms 1.07 V 41microA 7.40mA 180 147kohms .247V 54microA 8.24mA 152?? 94kohms .173V 85microA 8.31mA 97.76??? 47kohms .137V 171microA 8.35mA 48.83?????
What is going on?