The DC gain hFE and small signal gain hfe which is a minimum of 100 and a maximum of 400. If you are using the transistor as a switch use the DC gain, use the small signal gain
Data sheet only get average Beta value for all. To find out the exact value of 2N3904 that you owned, use transistor tester.
The current gain is given on the data sheet. As you can see it varies a lot. Good circuit designs employ biasing components so that the the performance of the circuit is more or less independent of the gain of the transistor.
The common-emitter current gain is represented by βF or hFE
I believe the formula was Ic / Ib. If that's the case, where can I verify it on the datasheet? Datasheet doesn't explicitly say "B" ... does anyone know?
I have a 2N3904 ...
Here is the site with the data sheets
http://wiki.mkrd.info/RadioShack_Transistors_Datasheets
The actual datasheet ..
http://wiki.mkrd.info/images/e/eb/MPS3904_datasheet.pdf
