In message <kt8hbj+5vsb@...>, dated Tue, 30 Jul 2013, jean_claudeabeille <jean_claudeabeille@...> writes:
Is anyboby here who can explain me how to calculate Ib in this circuit : Draft2.asc. I found no formula(s) on the web while LTSpice knows. Thanks.
You can't find a formula on the Web, even though there is one, because it's not a practical thing. The base current is exponentially dependent on the base voltage and the junction temperature. LTspice assumes values in the exponential equation, but the slightest change can make a huge difference to the current. Every individual transistor will give a different result.
You simply don't use bipolar transistors with a fixed DC voltage between base and emitter.
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