Can Step up transformer amplify signals?


by bukks bunny
Tags: amplifier, transformer, voltage gain
skeptic2
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#19
Feb3-13, 09:21 PM
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Quote Quote by NascentOxygen View Post
Hi bukks,


A transformer can step up the voltage, but in EE this is not referred to as amplification. It is termed magnification. The word "amplification" is restricted to applications involving an active device, viz., an amplifier. The distinction may seem slight, but in practice it really isn't.
Please support your statement with a reference.
russ_watters
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#20
Feb3-13, 10:05 PM
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Quote Quote by skeptic2 View Post
Please support your statement with a reference.
Et tu.

I'd like to see a reference that uses the word "amplify" to describe what a transformer does. It is much easier to prove a positive than a negative. Ie, the word "amplify" (or any relative) is not used in the wiki to describe the purpose of a transformer. That's not definitive proof, but it does imply it isn't an appropriate word use.

On the other hand, the wiki for "amplifier" says:
An electronic amplifier or amplifier is an electronic device used for increasing the power of a signal.
Which implies that the use "voltage amplifier" is an improper usage of the term.
The Electrician
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#21
Feb4-13, 02:05 AM
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In formal network theory it would be called "voltage transfer ratio".

Colloquially, I've always used "voltage gain" to mean an increase in voltage from input to output without implying anything about power gain or loss.
sophiecentaur
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#22
Feb4-13, 02:14 AM
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Quote Quote by skeptic2 View Post
Please support your statement with a reference.
Anyone can look in wiki and see what they have to say about what an amplifier does. The phraseology they use is "modulating the output of a power source". A transformer doesn't do that.
I know wiki may not be the ultimate source and we are only arguing semantics but you really are not helping peoples' general understanding by insisting otherwise.
Would you not agree that there is at least a difference between devices with and without a power source? In which case, what term would you use to differentiate?
skeptic2
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#23
Feb4-13, 08:39 AM
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Quote Quote by bukks bunny View Post
Hello friends.I was just wondering if a step up transformer can be used to amplify voltage signals like a transistor,as it step up input voltage at its output.?
Again, back to the OP's question, interpreted as the OP intended. I have already shown in post #13, that the OP used the word "amplify" within the context it is normally used, i.e. "to make larger, greater, or stronger; enlarge; extend." We do not expect all posters to be familiar with technical terms and use them in the narrow sense that may be common among engineers.

However, even technical dictionaries are divided on this issue. Here are a few references.


http://www.csgnetwork.com/glossarya.html

amplifier
A circuit that increases the voltage, current, or power of a signal.

http://elearning.zaou.ac.zm:8060/Sci...sco%202001.pdf

amplifier
Any device that increases the magnitude of an applied signal. It receives an input signal and delivers a larger output signal that, in addition to its increased amplitude, is a replica of the input signal. Also see CURRENT AMPLIFIER, POWER AMPLIFIER, and VOLTAGE AMPLIFIER.

voltage amplification
1. Abbreviation, Av. Amplification of an input-signal voltage to provide a
higher output-signal voltage. 2. Abbreviation, Av. The signal increase (Vout/Vin) resulting from this process. Also called voltage gain.

voltage-amplification device A low-current device designed especially for voltage amplification. It provides little or no power amplification.

voltage amplifier An amplifier operated primarily to increase a signal voltage. Compare CURRENT AMPLIFIER and POWER AMPLIFIER.


All these definitions are broad enough to include transformers as voltage amplifiers. As in the second definition for voltage amplification, (Vout/Vin) is voltage amplification, also called voltage gain. In the context of the question, that of whether transformers can amplify voltage similar to a transistor, the answer has to be yes.
sophiecentaur
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#24
Feb4-13, 09:33 AM
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Perhaps you could give an example where any of those 'types' of amplifier have been used and called an amplifier and consist only of a transformer.
Or could you also quote an example in which a voltage amplifier actually has a lower input impedance than its output impedance - resulting in no power gain? (or the inverse, with a current amplifier) Using an active amplifying device in a way that actually produces no power gain (strictly) would usually be poor engineering - except, perhaps, when a 'buffering' function is required and a transformer provides none of that.

Is not the whole point, for most posters of questions on this forum, to get themselves better informed about the topic on a technical level? They might as well be having a conversation down the pub with their friendly Bricklayer or Professor of History if they don't want to learn something from a reasonable authority about the subject of their question. Common usage of words is not applicable to any specialist topic in Science. It would too often be mis-usage - as in this case.

As for the actual wording of the OP. As has been stated before, the appropriate word would have been 'magnify' and not 'ampify' and I don't think pointing that out has causes any offense. bukks bunny doesn't seem to be complaining of rough treatment.
As its name suggests, a Transformer, Transforms.
NascentOxygen
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#25
Feb4-13, 09:35 AM
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Quote Quote by skeptic2 View Post
Again, back to the OP's question, interpreted as the OP intended.
Now that's a new perspective. (Even though you don't follow through with it.)

Maybe the OP wasn't questioning the industry usage of the word "amplify", maybe bukks bunny was questioning the use of transformers, and wondering whether they have applications apart from in AC power, i.e., I was just wondering if a step up transformer can be used to step up voltage signals in audio or RF applications?

Well, if that's the question, then yes, transformers are extensively used for audio and radio frequency applications, and they can be used to step up or step down. Ordinary mains transformers don't work well for higher frequencies, there need to be some manufacturing and material changes for these higher frequencies, but the transformers still work on the same principle.

Alas, I think bukks bunny has been scared off by the forum ruckus and retreated into his burrow.
sophiecentaur
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#26
Feb4-13, 09:56 AM
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I notice the OP uses the phrase "like a transistor". A transformer doesn't have or need a source of power so, in that respect, it is very much not like a transistor.

Perhaps bukks bunny could stick his nose out of his burrow, briefly, to say what he's got from this barrage of ire he's unleashed and tell us what he meant by his question. One could hardly blame him if he never came back - that would be a shame.
bukks bunny
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#27
Feb23-13, 01:55 AM
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heloo friends.First of all,sorry for my long leave as i had fallen sick.And thanks for all your response.What i was trying to figure out was that if a transformer can increase the amplitude of a voltage signal while preserving its exact shape why not it be used in place of bjt or fet votage amplifiers (as both do the same job).?
sophiecentaur
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#28
Feb23-13, 03:21 AM
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When all you need is increased amplitude of a voltage signal and when the pass-band is narrow then a transformer can be used. You need to realise that a transformer provides no buffering, though, and that precludes many of the functions that electronics performs.
A transformer is used when you want to transform the impedance of a signal, i.e. when it's appropriate.
If you have no power supply available, there are times when a transformer will perform a useful function. Why do you want it to be more than that?
NascentOxygen
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#29
Feb23-13, 05:14 AM
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Quote Quote by bukks bunny View Post
heloo friends.First of all,sorry for my long leave as i had fallen sick.
Welcome back. There should be a warning given to newcomers that involvement with PF can be a health hazard.
And thanks for all your response.What i was trying to figure out was that if a transformer can increase the amplitude of a voltage signal while preserving its exact shape why not it be used in place of bjt or fet votage amplifiers (as both do the same job).?
After the signal has been stepped-up by the transformer, what are you going to do with that signal? Most times you're going to feed it into an amplifier or some other electronic circuit. So why not incorporate the "magnifying" function into your electronic circuit and skip the transformer⁈
sophiecentaur
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#30
Feb23-13, 05:18 AM
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Quote Quote by bukks bunny View Post
heloo friends.First of all,sorry for my long leave as i had fallen sick.And thanks for all your response.What i was trying to figure out was that if a transformer can increase the amplitude of a voltage signal while preserving its exact shape why not it be used in place of bjt or fet votage amplifiers (as both do the same job).?
They don't.
bukks bunny
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#31
Feb23-13, 06:54 AM
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Quote Quote by sophiecentaur View Post
When all you need is increased amplitude of a voltage signal and when the pass-band is narrow then a transformer can be used.
As the prime concern was increasing the voltage amplitude(voltage gain) i guess i could use a step up tranformer in circuits where size doesnot matter.
sophiecentaur
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#32
Feb23-13, 07:33 AM
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Quote Quote by bukks bunny View Post
As the prime concern was increasing the voltage amplitude(voltage gain) i guess i could use a step up tranformer in circuits where size doesnot matter.
Do you 'have a thing' about transformers?
It is possible to knock a nail in a piece of wood, using a pickaxe but why would you want to?
Whilst there are occasions when all sorts of alternatives can be used to achieve a result, why not think in terms of using the standard approach? As I said before, there may be good reasons why you should not use a transformer in some circumstances. Wide-band transformers are very problematic and, of course, have infinite insertion loss at DC. They have their place but they are not amplifiers - end of.
This thread is going nowhere now. You have your answers so make your choice.


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