In practice, due to device mismatches the collector currents are unequal and this results in the difference flowing into the buffer's input resulting in an offset at its output.
42.
There is a full ( 100 % ) negative feedback; the two input base voltages and the emitter voltage change simultaneously while the collector currents and the total current do not change.
43.
The transition frequency is a function of the collector current, increasing with increasing current until a broad maximum at a collector current slightly less than what causes the onset of high injection.
44.
The transition frequency is a function of the collector current, increasing with increasing current until a broad maximum at a collector current slightly less than what causes the onset of high injection.
45.
Initially, current begins to flow through the resistor, secondary winding, and base-emitter junction ( see diagram ) which causes the transistor to begin conducting collector current through the primary winding.
46.
Hence, when it reaches a critical collector current, the base drive available becomes insufficient and the transistor starts to pinch off and the previously described positive feedback action occurs turning it hard off.
47.
If the voltage difference between the collector and emitter were zero ( or near zero ), the collector current would be limited only by the load resistance ( light bulb ) and the supply voltage.
48.
For translinear circuits, in which the exponential I V curve is key to the operation, the transistors are usually modeled as voltage-controlled current sources whose transconductance is proportional to their collector current.
49.
Note, however, that each additional right-half transistor " steals " a bit of collector current from Q 1 due to the non-zero base currents of the right-half transistors.
50.
Replacements for the 2N2222 are commonly available now in the cheaper TO-92 packaging, where it is known as the PN2222 or P2N2222, which has similar specifications except for the lower maximum collector current.
