I want to ask if someone would be willing to explain to me from scratch, how an amplifier works? I understand this is not a small task however all I really want is a response from someone who is willing and able to do this. This is a specific request so please do not reply in any other way.
I only have a basic knowledge of ohms law and some components but I really am anxious to attain an understanding of how amplifiers work because ever since I joined this forum I have been in ignorance for a long time now and I want to put an end to that.
I only have a basic knowledge of ohms law and some components but I really am anxious to attain an understanding of how amplifiers work because ever since I joined this forum I have been in ignorance for a long time now and I want to put an end to that.
That is far too general a question. An amplifier is simply something that can produce a larger amplitude than it is given. This can be accomplished with tubes or transistors, if you want to stick to the basic subject matter here.
With tubes, you vary the grid voltage a little and the plate current varies with it. If you put a dropping resistor in the plate circuit you will have a varying voltage that is controlled by the input.
The same can be said of putting a varying signal into the base of a transistor, making the collector current vary. With a resistor in the collector circuit, this can be made to give a varying collector voltage, and the variation can be larger than the signal you put into the base circuit.
Having said all that, maybe it's not circuit understanding you seek. Maybe you are referring to, say, an audio amplifier unit.
With tubes, you vary the grid voltage a little and the plate current varies with it. If you put a dropping resistor in the plate circuit you will have a varying voltage that is controlled by the input.
The same can be said of putting a varying signal into the base of a transistor, making the collector current vary. With a resistor in the collector circuit, this can be made to give a varying collector voltage, and the variation can be larger than the signal you put into the base circuit.
Having said all that, maybe it's not circuit understanding you seek. Maybe you are referring to, say, an audio amplifier unit.
Professor, that is very hard to answer in a place like this. You are basically asking how electronics works. Ohm's Law is important of course, but aside from each component and understanding what it does by itself, there is then the context of each part. A resistor Between two power supply nodes is doing something very different from one in the emitter leg of a basic transistor voltage amp stage. Capacitors likewise can be filters, couplers, decouplers, bypass caps. Everything has a context. If I have a cinder block, in one context it could be part of the foundation for my house, but in another context it is part of a bookshelf.
Not only is this not a small task, it is a huge task, and not something to be accomplished in 10 or 20 posts. And while electronics is electronics, most of the basic assumptions are different when comparing tube and solid state circuits.
There are basic tutorial texts on the subject. You can learn about the parts, like basic transistor circuits, op amp circuits, and tube circuits. If you go to National Semiconductor's site for example, you can learn from their "Analog U." U as in university. It is tutorial material. If you learn for example how A gain stage works, then the idea of stringing another one after it - two in a row - should click into place.
If you visit Solid State Guitar Amp Forum | DIY Guitar Amplifiers - Index, and look in the first section (Amplifier Discussion), the first item is a book written by teemuk about solid state amplifiers. It is aimed at guitar amplifiers, but amps are amps under the skin - the basic fuction of the circuits are the same as any amp. It is a free download.
If you want to learn about tubes, the classic text is the Radio Design Handbook. You can find used print copies, and they sell reprints of it, but you can also download it from a number of web sites. It has chapters on voltage amps, powr amps, power supplies, etc. Here is one source of it:
RDH4 mirror
Not only is this not a small task, it is a huge task, and not something to be accomplished in 10 or 20 posts. And while electronics is electronics, most of the basic assumptions are different when comparing tube and solid state circuits.
There are basic tutorial texts on the subject. You can learn about the parts, like basic transistor circuits, op amp circuits, and tube circuits. If you go to National Semiconductor's site for example, you can learn from their "Analog U." U as in university. It is tutorial material. If you learn for example how A gain stage works, then the idea of stringing another one after it - two in a row - should click into place.
If you visit Solid State Guitar Amp Forum | DIY Guitar Amplifiers - Index, and look in the first section (Amplifier Discussion), the first item is a book written by teemuk about solid state amplifiers. It is aimed at guitar amplifiers, but amps are amps under the skin - the basic fuction of the circuits are the same as any amp. It is a free download.
If you want to learn about tubes, the classic text is the Radio Design Handbook. You can find used print copies, and they sell reprints of it, but you can also download it from a number of web sites. It has chapters on voltage amps, powr amps, power supplies, etc. Here is one source of it:
RDH4 mirror
I know of no better way to fight ignorance than reading books. Too radical for you?
Sorry, but its my simple answer, just a reflex answer my be.
An amplifier supplied with power supply, then the amplifier simply amplify the input into output (load) by using power from power supply with its own transfer function characteristics.
Why a professor asking this?
Last edited:
ok lets try to do this in plain greek ....
a single transistor will "modulate" its power supply to audio signal
that will be barelly enough to produce a very small amount of power so more stages are to be added to produce more power and then more circuits to be added to support the above circuits
it could be wise ( since it seems that you dont like books) to take a look a pass labs where very simple amplifiers are detailed and presented with the principal of operation
after that you need to understand various class of amlifiers and some of them are very well explained in the esp pages
regards sakis
a single transistor will "modulate" its power supply to audio signal
that will be barelly enough to produce a very small amount of power so more stages are to be added to produce more power and then more circuits to be added to support the above circuits
it could be wise ( since it seems that you dont like books) to take a look a pass labs where very simple amplifiers are detailed and presented with the principal of operation
after that you need to understand various class of amlifiers and some of them are very well explained in the esp pages
regards sakis
Pass Labs!!!!!
without out doubt the explanation pages showing the workings of common emitter and common collector BJT single transistor amplifiers is a must read.
Common source and common drain are the jFET/mosFET equivalent.
The common collector/drain amplifier is also known as an emitter/source follower.
When you understand all the Pass tutorials then try reading some of the ESP literature.
Reading and understanding the Leach Lo-Tim paper is the next stage up from there.
If any particular sentence or paragraph or diagram is confusing, give us a link and quote it and we can try to explain that portion in a different way.
without out doubt the explanation pages showing the workings of common emitter and common collector BJT single transistor amplifiers is a must read.
Common source and common drain are the jFET/mosFET equivalent.
The common collector/drain amplifier is also known as an emitter/source follower.
When you understand all the Pass tutorials then try reading some of the ESP literature.
Reading and understanding the Leach Lo-Tim paper is the next stage up from there.
If any particular sentence or paragraph or diagram is confusing, give us a link and quote it and we can try to explain that portion in a different way.
Books books and more books... read all you can.
Experiment all you can.
This is particularly recommended,
The Art of Electronics: Amazon.co.uk: Paul Horowitz, Winfield Hill: Books
request it from your local library... even ours had a copy for years
Experiment all you can.
This is particularly recommended,
The Art of Electronics: Amazon.co.uk: Paul Horowitz, Winfield Hill: Books
request it from your local library... even ours had a copy for years
An amplifier takes quiet signal in and puts out a loud one.
To put this another way, an amplifier takes a low power signal in, and puts out a high power one.
The basic idea is that the output signal is an exact copy of the input signal but 'bigger' or more powerful.
The signal power is dependent on two factors, its voltage and its current. You can make the overall power bigger by increasing either the current or the voltage, or both.
In order for an amplifier to work, it must have a source of power available to it from which to construct the output signal.
Some devices, mostly 3-terminal devices, have the characteristic that when set up with an appropriate power supply, they will produce as an output a signal which is a magnified copy of the input signal. These are principally valves and transistors, although there are many varieties of transistor.
Electricity is often thought of as behaving like water, because of the way it flows from one place to another. Tubes are often called valves because their action resembles that of a valve or (water) tap. In a simple tap the flow of water is impeded by a blocking piece which moves in and out of the flow of water controlling the rate of flow or cutting it off completely. In a tube the flow of electrons from cathode to anode is impeded by the flow of electrons onto an intervening structure called the grid. This small flow has a more-or-less proportional effect on the greater flow between cathode and anode up to the point of cutting it off.
The comparison with water can be misleading, electrons in motion can create effects at a distance such as radio, which moving water obviously does not. At low frequencies and DC, however, the metaphor is quite apt.
In the nature of things, the amount of amplification which can be obtained from a single device is limited. A valve with a large flow has a minimum flow or drive requirement, to which it will respond with a full output swing.
Given that amplifiers are 3-terminal devices, they can be connected up in various different ways or configurations. These can offer increases in voltage, current or both. The designer must familiarise himself with these and choose which is appropriate given the drive requirements of the succeeding stage, or the speakers.
Just as in a plumbing system, the sizing of the parts is critical. The pipe that delivers water to all the houses is bigger than the pipe that leads to the shower-head. Unfortunately the flow of electricity is not visible in the same way that water is, and it is not really possible to design electronic systems in quite the same intuitive way as plumbing systems. Extensive familiarity with a range of parts capable of handling a range of powers is required.
No discussion of amplifiers can omit capacitors and inductors. These are used to manipulate the frequencies within the amplifier and isolate various stages operating at different DC levels. A thorough understanding of their types and their respective behaviours at AC and DC is required.
Learning to design an amplifier is not just a question of book-learning, although an acceptance of the necessity to actually read datasheets in detail is a must.
It's also a matter of repeated practise of comparatively trivial calculations, until it becomes as close to second nature as driving a car can become.
If you have the stomach for this, you can learn to design an amplifier.
w
To put this another way, an amplifier takes a low power signal in, and puts out a high power one.
The basic idea is that the output signal is an exact copy of the input signal but 'bigger' or more powerful.
The signal power is dependent on two factors, its voltage and its current. You can make the overall power bigger by increasing either the current or the voltage, or both.
In order for an amplifier to work, it must have a source of power available to it from which to construct the output signal.
Some devices, mostly 3-terminal devices, have the characteristic that when set up with an appropriate power supply, they will produce as an output a signal which is a magnified copy of the input signal. These are principally valves and transistors, although there are many varieties of transistor.
Electricity is often thought of as behaving like water, because of the way it flows from one place to another. Tubes are often called valves because their action resembles that of a valve or (water) tap. In a simple tap the flow of water is impeded by a blocking piece which moves in and out of the flow of water controlling the rate of flow or cutting it off completely. In a tube the flow of electrons from cathode to anode is impeded by the flow of electrons onto an intervening structure called the grid. This small flow has a more-or-less proportional effect on the greater flow between cathode and anode up to the point of cutting it off.
The comparison with water can be misleading, electrons in motion can create effects at a distance such as radio, which moving water obviously does not. At low frequencies and DC, however, the metaphor is quite apt.
In the nature of things, the amount of amplification which can be obtained from a single device is limited. A valve with a large flow has a minimum flow or drive requirement, to which it will respond with a full output swing.
Given that amplifiers are 3-terminal devices, they can be connected up in various different ways or configurations. These can offer increases in voltage, current or both. The designer must familiarise himself with these and choose which is appropriate given the drive requirements of the succeeding stage, or the speakers.
Just as in a plumbing system, the sizing of the parts is critical. The pipe that delivers water to all the houses is bigger than the pipe that leads to the shower-head. Unfortunately the flow of electricity is not visible in the same way that water is, and it is not really possible to design electronic systems in quite the same intuitive way as plumbing systems. Extensive familiarity with a range of parts capable of handling a range of powers is required.
No discussion of amplifiers can omit capacitors and inductors. These are used to manipulate the frequencies within the amplifier and isolate various stages operating at different DC levels. A thorough understanding of their types and their respective behaviours at AC and DC is required.
Learning to design an amplifier is not just a question of book-learning, although an acceptance of the necessity to actually read datasheets in detail is a must.
It's also a matter of repeated practise of comparatively trivial calculations, until it becomes as close to second nature as driving a car can become.
If you have the stomach for this, you can learn to design an amplifier.
w
Last edited:
Well, it's certainly a vague request. We have no idea what your background is other than it is clear that you are not a professor (or else you would have gone to the library and researched the topic already).
The Pass literature is an excellent start. I would supplement it by getting a used copy of Linsley-Hood's "Art of Linear Electronics". This will have appropriate background material also. At this point I would not bother with the Horowitz and Hill, since it will be too advanced for you.
I will be candid, if you expect someone else to magically condense the information and feed it to you, then you will never get anywhere. You are going to have to roll up your sleeves and do some work. Start with the suggested reading. If your background is restricted to Ohm's law, then you have got some work to do. Others can not do it for you.
The Pass literature is an excellent start. I would supplement it by getting a used copy of Linsley-Hood's "Art of Linear Electronics". This will have appropriate background material also. At this point I would not bother with the Horowitz and Hill, since it will be too advanced for you.
I will be candid, if you expect someone else to magically condense the information and feed it to you, then you will never get anywhere. You are going to have to roll up your sleeves and do some work. Start with the suggested reading. If your background is restricted to Ohm's law, then you have got some work to do. Others can not do it for you.
Yes, but there are a number of classic circuits employing active components interacting with each other, such as the darlington, the cascode or the long tailed pair which might be elements in a string or cascade of devices and which are frequently analyzed as a block.
w
Professor smith should know about a little place called howstuffworks.com That's really the place to start learning before coming here.
HowStuffWorks "Search"
HowStuffWorks "Search"
After you have gone through the basic literature, there an article from Rod Elliot that takes you a little deeper and to my eyes is well written.
Howstuffworks
Howstuffworks
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.