So I've read through the allaboutcircuits.com, art of electronics, and a few other treatments on transistor amplifiers, and while I generally understand them, a few questions are sticking out in my mind. I've tried my best to come up with my own solutions before I turn to you guys/girls, but still a few remain...
One thing that is confusing me is the base input current. The way I understand it is that in a common-emitter amplifier configuration, like the one a quarter down http://www.allaboutcircuits.com/vol_3/chpt_4/5.html, the resistor is used becuase the mic input might go above the forward voltage drop of the diode. If the resistor was not there, then the excess voltage would have to drop over a short circuit (since the emitter is connected to ground). In the previous example with just a solar cell, the resistor is omitted, however if the solar cell can not put out a voltage greater than the diode drop, wouldnt the transistor never even turn on?
Lastly, when biasing, two resistors are used in a divider network. However in calculations these resistors are considered to be in parallel eventhough both their ends do not share common points. One side does, but the other is connected across a battery. I must be misunderstanding something about the definition of a parallel circuit.
As always, many many thanks for any insight that you can provide. Like I said, I really do try to answer my own questions, but sometimes (ok, often) the answers elude me.
One thing that is confusing me is the base input current. The way I understand it is that in a common-emitter amplifier configuration, like the one a quarter down http://www.allaboutcircuits.com/vol_3/chpt_4/5.html, the resistor is used becuase the mic input might go above the forward voltage drop of the diode. If the resistor was not there, then the excess voltage would have to drop over a short circuit (since the emitter is connected to ground). In the previous example with just a solar cell, the resistor is omitted, however if the solar cell can not put out a voltage greater than the diode drop, wouldnt the transistor never even turn on?
Lastly, when biasing, two resistors are used in a divider network. However in calculations these resistors are considered to be in parallel eventhough both their ends do not share common points. One side does, but the other is connected across a battery. I must be misunderstanding something about the definition of a parallel circuit.
As always, many many thanks for any insight that you can provide. Like I said, I really do try to answer my own questions, but sometimes (ok, often) the answers elude me.