Does a transistor have positive and negative terminals?

A transistor is an active device with three terminals, and these three terminals are known as the Emitter (E), the Base (B), and the Collector (C) (Fig. 1). The Base is responsible for controlling the transistor while the Collector is the positive lead, and Emitter is the negative lead.

How a transistor can be used as a switch?

One of the most common uses for transistors in an electronic circuit is as simple switches. In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on.

How does current flow through a transistor?

We know that in transistors and diodes, electric current is carried by both free electrons and holes. Free electrons and holes travel in opposite directions. For example, if free electrons flow from left to right then the holes will flow from right to left.

What happens in saturation region of transistor?

Saturation region This is the region in which transistor tends to behave as a closed switch. The transistor has the effect of its collector and Emitter being shorted. The collector and Emitter currents are maximum in this mode of operation.

What is base current in transistor?

Base current is typically 1\% of emitter or collector current for small signal transistors. Thus 99\% of the emitter current flows into the collector. It is controlled by the base current, which is 1\% of the emitter current. This is a potential current gain of 99, the ratio of IC/IB , also known as beta, β.

How is base voltage of a transistor calculated?

This can be done using the formula: Vcc = Vrc + Vrb + Vbe + (Ic + Ib)Rc + IbRb + Vbe, where “Vrc” is the voltage across the collector resistor; “Vrb” is the voltage across the base resistor (connected across the base) and the junction between the collector resistor and the transistor collector; and “Vbe” is the voltage …

How can a transistor be used as an amplifier or a switch?

The transistor will operate as an amplifier or other linear circuit if the transistor is biased into the linear region. The transistor can be used as a switch if biased in the saturation and cut-off regions. This allows current to flow (or not) in other parts of a circuit.

What is transistor modes and to use transistor as a switch which modes are used?

Using a transistor as a switch is the simplest application of the device. A transistor can be extensively used for switching operation either for opening or closing of a circuit. Generally, the low voltage DC is turned on or off by transistors in this mode. Both PNP and NPN transistors can be utilized as switches.

What does the base do in a transistor?

The base is the gate controller device for the larger electrical supply. The collector is the larger electrical supply, and the emitter is the outlet for that supply. By sending varying levels of current from the base, the amount of current flowing through the gate from the collector may be regulated.

Can a transistor conduct both ways?

Transistors operate on DC current, they do not conduct both ways and can easily be damaged by high reverse voltages.

When both emitter-base and collector-base junction is forward biased the transistor is in?

In the cut-off region both junctions are reversed biased and in saturation region both base-emitter and base-collector junctions are forward biased as in this region high currents flows as both junctions of the transistor are forward biased and bulk resistance offered is very much less.

How do you take saturation and cutoff regions in a transistor operation?

When load line intersect IB = 0, it is known as cut off region of the transistor. As the base current is zero, only small collector leakage current flows. The base emitter junction does not remain in the forward biased because the base current is zero….Cut off, Active & Saturation Region of Transistor.

Region	Base – emitter diode	Emitter – collector diode
Active	ON	OFF

What are the construction and terminal voltages for a bipolar NPN transistor?

The construction and terminal voltages for a bipolar NPN transistor are shown above. The voltage between the Base and Emitter ( VBE ), is positive at the Base and negative at the Emitter because for an NPN transistor, the Base terminal is always positive with respect to the Emitter.

What is common base and common emitter configuration of transistor?

Each method of connection responding differently to its input signal within a circuit as the static characteristics of the transistor vary with each circuit arrangement. Common Base Configuration – has Voltage Gain but no Current Gain. Common Emitter Configuration – has both Current and Voltage Gain.

What happens when the base current is high in a transistor?

Also when the base current is high the corresponding collector current will also be high resulting in the base current controlling the collector current. One of the most important properties of the Bipolar Junction Transistor is that a small base current can control a much larger collector current.

What is the voltage drop between the base and emitter terminals?

Also, there is a voltage drop between the Base and the Emitter terminal of about 0.7V (one diode volt drop) for silicon devices as the input characteristics of an NPN Transistor are of a forward biased diode.