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Vb = Vi - Vbe(sat) = 3.3 - 1.2 = 2.1v
Calculating using Ib=Ic/10 (*** Best Approach)
It is common to assume that base current is 1/10 of the collector current.
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Rb = Vb/Ibx3 = 2.1/(0.00078x3) = 897 Ω
This would be the max value for Rb.
Calculating using the online calculator
See reference
hFE=100
Rb = 960 Ω
This would be the max value for Rb.
Why are these all so different??? I gues it would work from 200 to 1KΩ.
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