Hey again guys. I find that i am still having alot of trouble understanding how the common collector works.
In the allaboutcircuits site this example is used:
In the text, the author says that the voltage across the be pn junction will always be around .7 volts with the rest of the input signal across the 5kohm resistor. If this is the case then at the peak, the current through the resistor should be: 3.1/5000 = .62 milliamps. I know this is wrong but howcome this .62 milliamps doesnt go through the base? Shouldnt all the input current go through the base?
Even if as the circuit describes, current is beta plus 1. Then the current through the base should be emitter current/beta+1 For this to occur hie or imput inpedance would have to be very high which it is. But if this is the case that the input inpedance was very high then surely most of the voltage would be dropped across hie and not Rload? As these two "resistors" are connected in series as far as the input is concerned, and the load resistor being only 5 kohms should drop a tiny voltage with respect to hie.
I know i am not doing a very good job of explaining myself but i just dont get how this circuit does what it does.
Help!
In the allaboutcircuits site this example is used:
In the text, the author says that the voltage across the be pn junction will always be around .7 volts with the rest of the input signal across the 5kohm resistor. If this is the case then at the peak, the current through the resistor should be: 3.1/5000 = .62 milliamps. I know this is wrong but howcome this .62 milliamps doesnt go through the base? Shouldnt all the input current go through the base?
Even if as the circuit describes, current is beta plus 1. Then the current through the base should be emitter current/beta+1 For this to occur hie or imput inpedance would have to be very high which it is. But if this is the case that the input inpedance was very high then surely most of the voltage would be dropped across hie and not Rload? As these two "resistors" are connected in series as far as the input is concerned, and the load resistor being only 5 kohms should drop a tiny voltage with respect to hie.
I know i am not doing a very good job of explaining myself but i just dont get how this circuit does what it does.
Help!