# What are the basics of a transistor circuit?

## What are the basics of a transistor circuit?

Transistor basics •Emitter to base junction is forward biased (normally) •Collector to base junction is reverse biased (normally) •Transistors are current operated devices, so KCL should be applied first: –I E = I C + I B Basics continued •Leakage current: I CBO (Emitter open) –Usually is considered negligible, but can affect things when I C

Which is the emitter and collector of a transistor?

The arrow-head in the above figures indicated the emitter of a transistor. As the collector of a transistor has to dissipate much greater power, it is made large. Due to the specific functions of emitter and collector, they are not interchangeable. Hence the terminals are always to be kept in mind while using a transistor.

### How does biasing control the operation of a transistor?

Biasing is controlling the operation of the circuit by providing power supply. The function of both the PN junctions is controlled by providing bias to the circuit through some dc supply. The figure below shows how a transistor is biased.

What are the four operating modes of a transistor?

The four transistor operation modes are: Saturation — The transistor acts like a short circuit. Current freely flows from collector to emitter. Cut-off — The transistor acts like an open circuit.

#### How are transistors T1 and T2 used in a circuit?

Transistors T1 and T2 form a high current gain Darlington pair for controlling the output voltage. Since the design is basically an emitter follower, the emitter output follows the base voltage, which means varying the base voltage proportionately varies the emitter output voltage.

How many transistors are used in a Darlington circuit?

The circuit provides good load regulation, its maximum current being not more than 500mA, sufficient for most applications. This circuit is built around just two transistors as the main active components. The configuration is in the form of a standard Darlington pair, which increases its current amplification capacity hugely.

## What can you do with a PCB transistor circuit?

PCB Design for the above transistorized stabilized power supply can be seen in the following figure. This simple 30 watt fully transistorized amplifier circuit can be used for powering small speaker systems from USB or from mobile, Ipod music sources. The unit will provide great sounding amplified music output sufficient for any small room.

When was Changjiang electronics co.ltd.established?

Changjiang Electronics Technology Co., Ltd. was established in 1972 and successfully listed on the main board of the Shanghai Stock Exchange in 2003.

### What is the minimum current gain of a transistor?

One of the key characteristics of the transistor is the current gain. This number describes how much the emitter current changes for a given change in the base current. The current gain varies with the amount of current flowing in the collector. For the 2N3904, the minimum current gain at 0.1 mA collector current is 40.

Which is the correct way to apply KCL to a transistor?

Transistor basics •Emitter to base junction is forward biased (normally) •Collector to base junction is reverse biased (normally) •Transistors are current operated devices, so KCL should be applied first: –I E = I C + I B