In my quest as a noob to better understand transistors, I have been reading up on calculating the base current to fully saturate the transistor. The guide that I read says to use the minimum value HFE value but on datasheets I see several minimum HFE values listed for specific collector current and voltage combinations. Should I select the smallest HFE value out of those listed to be on the safe side?
For example, I'm looking at the datasheet for the BD139 transistor (www.fairchildsemi.com/ds/BD/BD135.pdf?. If I had a collector voltage of 5 volts and a load that consumes 60mA should I use the HFE value of 25 to get 2.4 mA base current(I have also read various things about doubling the base current to be on the safe side)?