- #1
neorich
- 20
- 1
"Transistor Action"
Dear Forum,
I have a question about what is often referred to as "transistor action".
I understand how a transistor operates within a circuit, and the characteristics of such a circuit, but I would like to learn physically how the bipolar transistor is able to control a collector current through base current or base voltage?
Lets assume the transistor is properly biased and the base emitter junction is passing current i.e. Vbe>0.6V. When a base voltage is applied and hence a base current is flowing there then appears a collector current of hfe*Ib. OK. This collector current is supplied by the source (normally written as Vcc).
Can you please answer the following questions.
1.) Does a change in base voltage (or current) cause the collector voltage (voltage at the bottom of a collector resistor) to change, thereby causing a change in current where the current is given by (Vcc-Vc)/Rc.?
2.) If this is the case, how does the change in Vb get "translated" into a change in Vc?
3.) Does a change in base current (or voltage) cause a change collector current to be drawn which then passes through the resistor and drops a voltage thereby changing the collector voltage i.e. Vc=Vcc-IcR?
4.) I guess this question is does the collector voltage change first, leading to a change in collector current, OR does the collector current change first leading to a change in collector voltage?
5.) Now for the interesting question. Whether 1 or 3 is correct (or both, or neither) how does the change in Vb (or Ib) pass through the transistor and lead to a change in Vc (or Ic). What physical processes are happening in the transistor materials. Mathematical or qualitative explanations welcomed.
Thank you very much.
Kind Regards
neorich
Dear Forum,
I have a question about what is often referred to as "transistor action".
I understand how a transistor operates within a circuit, and the characteristics of such a circuit, but I would like to learn physically how the bipolar transistor is able to control a collector current through base current or base voltage?
Lets assume the transistor is properly biased and the base emitter junction is passing current i.e. Vbe>0.6V. When a base voltage is applied and hence a base current is flowing there then appears a collector current of hfe*Ib. OK. This collector current is supplied by the source (normally written as Vcc).
Can you please answer the following questions.
1.) Does a change in base voltage (or current) cause the collector voltage (voltage at the bottom of a collector resistor) to change, thereby causing a change in current where the current is given by (Vcc-Vc)/Rc.?
2.) If this is the case, how does the change in Vb get "translated" into a change in Vc?
3.) Does a change in base current (or voltage) cause a change collector current to be drawn which then passes through the resistor and drops a voltage thereby changing the collector voltage i.e. Vc=Vcc-IcR?
4.) I guess this question is does the collector voltage change first, leading to a change in collector current, OR does the collector current change first leading to a change in collector voltage?
5.) Now for the interesting question. Whether 1 or 3 is correct (or both, or neither) how does the change in Vb (or Ib) pass through the transistor and lead to a change in Vc (or Ic). What physical processes are happening in the transistor materials. Mathematical or qualitative explanations welcomed.
Thank you very much.
Kind Regards
neorich