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Why does a Class A amplifier use a Darlington transistor?
Above figure shows a class A amplifier circuit that uses a Darlington transistor configuration to have a high collector current. Darlington transistor offers a gain that equal to the product of two individual gains. Therefore, with a small base current, the output current at the collector terminal is very high.
Which is Darlington Class AB push pull amplifier?
The Darlington class AB push-pull amplifier is shown in the below figure. 7.19 There is a need of 4 diodes in the bias circuitry to fulfill the 4 base-emitter junctions of 2 Darlington pair. The complementary Darlington also called Sziklai pair.
What is the power output of a class AB amplifier?
Class AB Amplifier. We have seen that the power output of an amplifier is the product of the voltage and current, (P = V*I) applied to the load, while the power input is the product of the DC voltage and current taken from the power supply.
What is the current gain of a Darlington pair circuit?
This means that if two transistors with modest current gains of 50 were used, then the overall current gain would be 50 x 50 = 2500. Although the Darlington pair circuit is often used in its basic format, it is often seen with a bypass resistor between the base and emitter connections of the final transistor.
How does a 100K ohm resistor work on a Darlington pair?
A 100k ohm resistor acts as a protective resistor for the pair of transistors. When the switch is closed, a specified voltage greater than 1.4V is applied across the Darlington transistor. This causes the Darlington pair to become active and drives the current through the load.
How does the NPN configuration of Darlington transistor work?
Consider the NPN configuration of Darlington transistor. In this a very small base current causes a large emitter current to flow which is then applied to the base of the next transistor. Amplified current in the first transistor is again amplified by the current gain of the second transistor.
What happens to the Darlington pair when water level increases?
Therefore, the circuit becomes open and no current flows through it. As the water level increases, sensor become active and gives a necessary base current to the Darlington pair. Therefore, the circuit becomes short and load current flows so that the buzzer gives an alarm or sound.