Are NPN and PNP transistors interchangeable?

Are NPN and PNP transistors interchangeable?

Answer: NPN and PNP transistors are interchangeable if you remember one simple rule: A bipolar transistor is essentially two back-to-back diodes with the base being the common connection. On the left is an NPN (negative-positive-negative) transistor and on the right is a PNP (positive-negative-positive) transistor.

What are the characteristic features of a Darlington Pair?

Darlington pair attributes High current gain: It has already been seen that the current gain from the Darlington is very high. Figures in excess of several thousand are often seen. Base emitter voltage: The Darlington pair exhibits a higher voltage between the input base and the output emitter than a single transistor.

How many transistors are required to make a Darlington Pair?

Two
Two NPN transistors are connected together in the form of a Darlington Pair to switch a 12V 75W halogen lamp. If the forward current gain of the first transistor is 25 and the forward current gain (Beta) of the second transistor is 80.

Which type of coupling is used in Darlington Pair amplifier?

Darlington pair is a special arrangement of two standard NPN or PNP bipolar junction transistors (BJT) connected together. The Emitter of one transistor is connected to the base of the other to produce a more sensitive transistor with a much larger current gain.

Are all PNP transistors the same?

Making of PNP Transistor The characteristics of both PNP and NPN transistors are similar except that the biasing of the voltage and current directions are reversed for any one of the possible three configurations such as a common base(CB), common emitter(CE) and common collector(CC).

What are Darlington transistors used for?

Applications of Darlington Transistor Darlington transistors are mainly used in switching and amplification applications for delivering a very high DC current gain. Some of the key applications are high and low side switches, sensor amplifiers and audio amplifiers.

How do you make a Darlington pair transistor?

Darlington Transistor or Darlington Pair The pair of bipolar transistors provides a very high current gain as compared with single standard transistor as mentioned above. A pair of these transistors can be PNP or NPN depends on the application used.

Which is a Darlington pair?

In electronics, a multi-transistor configuration called the Darlington configuration (commonly called a Darlington pair) is a circuit consisting of two bipolar transistors with the emitter of one transistor connected to the base of the other, such that the current amplified by the first transistor is amplified further …

What are Darlington transistor used for?

The Darlington transistor circuit lends itself to use in small driver chips for LEDs and other small devices. The high current gain of the Darlington circuit means that these small driver chips can be used to interface LEDs and other devices to logic chips.

Why are NPN transistors more commonly used than PNP transistors?

As the electrons have higher or faster mobility than holes, the conductivity also more. For this reason, NPN transistors are more preferable than PNP transistors because the NPN transistor provides more conductivity. We know that in electronic circuits all the negative(-ve) or common terminals are grounded.

Why do we use Darlington pairs in BJT transistors?

In typical BJT transistor the current gain is limited depending on the transistor specification. But in some cases the application needs more current gain that a single BJT transistor couldn’t provide. The Darlington pair is perfect for the application where high current gain is needed.

What is the difference between PNP Darlington and NPN Darlington transistors?

If the Darlington pair consists of both PNP transistors, it makes PNP Darlington Transistor. And if the Darlington pair consists of both NPN transistors, it makes NPN Darlington Transistor.

What are the disadvantages of a Darlington transistor?

But when the Darlington pair is in saturated region or fully on condition, there are voltage drop across base and emitter. It is a main disadvantage for a Darlington pair. The voltage drops range from .3V to 1.2v. Due to this voltage drop the Darlington transistor get hotter when in fully on mode and supplying current to the load.

What is the overall current gain of a Darlington pair?

This transistor behaves as a single unit transistor as it has only one emitter, collector, and base. The Darlington transistor was invented by Sidney Darlington in 1953. If the current gain of a transistor is β1 and β2, the overall current gain of Darlington pair is β1β2.