BJT and finding Resistance

Thread Starter

uofmx12

Joined Mar 8, 2011
55
If I had this circuit:
http://i812.photobucket.com/albums/zz41/uofmx12/ckt31.jpg

If Rb had zero current flowing through it. I need to calculate the input resistance looking into the BJT. Rin=Vin/Iin, Vin is input voltage to BJT.

The bottom is voltage divider. I know the 10k resistor before the BJT will be va and vb on each side with Iin going through. So if Rin=Vin/Iin = vb/Iin.
Would Iin=voltage through divider - vb / 10k?
 
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