StayatHomeElectronics
- Joined Sep 25, 2008
- 1,073
If there is no electron flow through R2 then there is no voltage across R2. Since R2 is in parallel with the base-emitter junction of the transistor, there is no V(be). This in turn causes the transistor to be off.
So, your statement that no electrons flow through R2 is incorrect.
You also say that the electrons do not automatically start from the emitter. The -terminal of the supply pushes it by being a source of electrons. It also pushes electrons through R2 as it has no preference for the transistor.
Considering only the transistor, the electrons from the emitter do then flow through the collector and the base. The amount of doping sets up the relationship and the controls needed to accomplish this. Because of the way the device is created, i.e. doped, etc..., the relationship of currents and voltages is established.
Ic = beta * Ib
Ie = (beta + 1) * Ib
I believe the Ebers-Moll model sets up the relationships of the currents to the external excitation voltages, V(be) and V(ce).
Given these detailed relationships of the currents and the voltages, the transistor can be used to control the amount of current that flows through it.
The model of the transistor needs to be inserted into the circuit and not take over the circuit. R1 and R2 are typically used to bias the transistor ON so the current will flow at all.
So, your statement that no electrons flow through R2 is incorrect.
You also say that the electrons do not automatically start from the emitter. The -terminal of the supply pushes it by being a source of electrons. It also pushes electrons through R2 as it has no preference for the transistor.
Considering only the transistor, the electrons from the emitter do then flow through the collector and the base. The amount of doping sets up the relationship and the controls needed to accomplish this. Because of the way the device is created, i.e. doped, etc..., the relationship of currents and voltages is established.
Ic = beta * Ib
Ie = (beta + 1) * Ib
I believe the Ebers-Moll model sets up the relationships of the currents to the external excitation voltages, V(be) and V(ce).
Given these detailed relationships of the currents and the voltages, the transistor can be used to control the amount of current that flows through it.
The model of the transistor needs to be inserted into the circuit and not take over the circuit. R1 and R2 are typically used to bias the transistor ON so the current will flow at all.