ABSTRACT
Although the transistor (a term derived from ‘‘trans-resistor,’’ referring to a device that can easily change resistance) operates under a different electrical principle, the valve analogy is still relevant. Figure 10.4 shows a basic amplifier schematic with a DC power source that’s been set up across the transistor’s collector and emitter points. Now, let’s revisit the valve analogy. By presenting a small control voltage at the transistor’s base, it’s possible for a corresponding change in the resistance to be introduced between the collector and emitter. This allows a much larger and corresponding voltage/current to be passed from the supply source through to the device’s output.
