BJT beta vs Hfe

[king.oslo]

Hello there,

Since the day when I began playing with BJTs, I understood that BJT beta = Ic/Ib, which is distinct from h_fe. Hfe is the value from the data sheet which is typical maximum current gain from that transistor in the common emitter configuration.

Beta is amongst other things, dependent on the configuration of the transistor.

When I know Q1 has a beta of 200, and I know the collector current is 6mA, base current must be 30u. Will somebody kindly confirm that this is correct? Due to recent event, I want to be sure that I have understood correctly.

Hope it isn't too much trouble.

Thank you for your time.

Kind regards,
Marius

[jebcom]

Beta is also usually specified in the common emitter configuration, so Hfe is usually the same as DC beta.
So yes, I believe you are correct, if the transistor is forward biased, 200 is the actual beta, and you are talking about DC.

[jebcom]

And by the way, if you want to get it first hand from the Bible, you can read or download it here:
http://ebookbrowse.com/ge-transistor-manual-1964-pdf-d258054104

[Paul Price]

Yes very true, but realize that Beta is a statistical variable and the actual Beta will be in a range around the specified value in a data sheet for a large group of the same transistor, so a Beta of 200 might be as much as 500 or more as little as 50, depending on the range of values specified in a data sheet.

The Beta value is usually a "typical" value that varies with temperature and each device and especially with collector current.