Question

We know that transistor can be used as switch or an amplifier.

1. What is the real difference between transistor as a switch and as an amplifier? How is it used in the circuits for both the purpose?

2. What are the basic knowledge I require to use the transistors in various circuits (to design my own circuit)?

3. When do we need npn and when do we need pnp transistor?

4. What are the basic attributes of a transistor which we should know to make hobby circuits from scratch?

Answer 1

first.. do you know what is the difference between a switch and an amplifier?

Answer 2

Yes. I do. A switch is used for switching a something on or off. An amplifier is for boosting a signal. (I just read transistor can boost only current signals)

Answer 3

The operating point, as a switch the transistor is driven quickly into saturation or quickly cut off (on-off). As an amplifiers it is operated within its dynamic range. This is accomplished by selecting bias levels that allow such operation. Transistors can operate as different "class" of amplifiers as well as voltage, current and power amplifiers.

Answer 4

Thank you very much . Do you mean there are different types of transistors namely voltage, current and power transistors? OR based on the circuit arrangement, any transistor can behave as voltage, current or power amplifier?

I understood that common emitter is the most common biasing. Is it ok, if I just concentrate on learning that?

What do you mean by 'dynamic range' of transistor?

As always, thanks in advance!

Answer 5

I understood Current and Voltage. What really is POWER? What is its importance?

Answer 6

A power amplifier amplifies both current and voltage. There are transistors that are called power transistors because they have the capability to handle large amount of power with appropriate heat sinks and cooling.The common emitter is a popular configuration, but there are many uses for the common collector and common base configuration. The common collector sometimes called an emitter follower is used to drive coaxial cables and other low impedance devices..

By dynamic range, I am referring to the operating range where the output remains undistorted with an appropriate range of input signal levels.

Answer 7

Sorry for the delay in thanking you. Thank you very much. As always you are really helpful and kind.

Could you please suggest some problems(exercise) related to transistors so that I will know the complete concept of transistor in electronics circuits?

Answer 8

There are many places where you can find information on transistors. My informations were manuals provided by U.S. Army, and the FAA Aeronautical Center (FAA Academy) at Oklahoma City, OK. I no longer have these manuals, but there is plenty of similar information available on the internet. Wiki Books come to mind, there are a variety of kinds of transistors or solid state devices. I was introduced to the bi-polar transistor in the 1960s, now there are FET (field effect transistor) that are very popular (MOSFET, IGFET etc) The big thing now is Programmable Arrays, OpAmps, PLC (programmable logic controllers) All of this can be found on the internet.

Just research them as you are introduced to them, I take it you are in some kind of course, just keep pace with the course and research the items that are confusing you. Good luck with it.