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How is amplification possible in a transistor?
A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. Thus a small input voltage results in a large output voltage, which shows that the transistor works as an amplifier.
How are transistors controlled?
A transistor can use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals. A small current at the base terminal (that is, flowing between the base and the emitter) can control or switch a much larger current between the collector and emitter terminals.
How do you achieve amplification?
Amplifier gain is simply the ratio of the output divided-by the input. Gain has no units as its a ratio, but in Electronics it is commonly given the symbol “A”, for Amplification. Then the gain of an amplifier is simply calculated as the “output signal divided by the input signal”.
Why do we amplify signals?
Most of the electrical signals that record sounds are very weak. This means, literally, that the amplitude of the signal has to be increased. One way to amplify a signal is to use an operational amplifier (op-amp) with two resistors connected to form an amplifying feedback circuit, as shown in Figure 37.
Can we make amplifier with any transistor?
In order to build an amplifier, all you need are a transistor, a power source, some resistors, and some capacitors. Why is it called a “common emitter amplifier?” – because the base is the input, the collector is the output, and the “common” or ground is the emitter.
How does a transistor work as an amplifier?
The load resistance is of high value which causes a large voltage drop. Overall, the weak signal is thus amplified in the collector circuit. However, to work as an amplifier, the transistor has to work in the active region of the output voltage versus input voltage curve as seen in the figure below.
How are transistors used to control high voltage?
Transistors are often used as electronic switches, to control loads which require high voltage and current from a lower voltage and current. The most common example you’ll see of this in a physical computing class is to use an output pin of a microcontroller to turn on a motor or other high current device.
Why does a transistor have a low resistance?
The low resistance in input circuit, lets any small change in input signal to result in an appreciable change in the output. The emitter current caused by the input signal contributes the collector current, which when flows through the load resistor R L, results in a large voltage drop across it.
How is the load collected in a transistor?
The load is connected at the collector of a transistor and for a single-stage amplifier, the output voltage is taken from the collector of the transistor and for a multi-stage amplifier, the same is collected from a cascaded stages of transistor circuit. By definition, it is the total load as seen by the a.c. collector current.