R3 and R4 then act as a voltage divider that makes Q1's base voltage negative and consequently turns off Q1.
12.
The degrees of freedom are the choice of the base voltage ( V ) and the base power ( S ).
13.
CC is due to the Early effect, which causes the ? of the transistor to change with its collector-to-base voltage " V"
14.
In a grounded-emitter transistor circuit, such as the light-switch circuit shown, as the base voltage rises, the emitter and collector currents rise exponentially.
15.
The Q2 base voltage is determined by the mentioned divider so that Q2 is conducting and the trigger output is in the low state.
16.
Some basic circuits can be designed by assuming that the emitter base voltage is approximately constant, and that collector current is beta times the base current.
17.
Another modification was introduced to address this issue, using three separate guns, each fed with a different base voltage tuned to hit one of the layers.
18.
In this circuit, the voltage divider holds the base voltage fixed independent of base current provided the divider current is large compared to the base current.
19.
In this case, the base voltage divider is usually connected to the transistor's collector rather than V CC, providing negative feedback that stabilizes I E and I C.
20.
In the present circuit, if the input voltages change in the same direction, the negative feedback makes Q3 / Q4 base voltage follow ( with 2 " V"
