it depends on what you wan tto amplify: afterall, isn't amplifier just a device that amplifies something? a coke bottle bottom is an amplifier (of images), a hydrolic brake system amplifies force, a torque wrench amplifies, dada!, torque, and a voltage amplifier amplifies voltage and a power amplifier amplifies power.
the original poster asked for "amplifier" not "power amplifier".
so let's stick to that and don't narrow the discussion down to power amplifier.
the original poster asked for "amplifier" not "power amplifier".
so let's stick to that and don't narrow the discussion down to power amplifier.
I'd suggest a torque wrench is more like a transformer than an amplifier in the sense that the force is magnified but there is no additional energy involved.
I think the term "amplifier" ought to imply additional energy.
By this definition a car could be called a mechanical amplifier as the accelerator pedal displacement is converted into wheel torque using the energy from petrol (that's gasoline to you North Americans). But a bicycle is not an amplifier.
I think the term "amplifier" ought to imply additional energy.
By this definition a car could be called a mechanical amplifier as the accelerator pedal displacement is converted into wheel torque using the energy from petrol (that's gasoline to you North Americans). But a bicycle is not an amplifier.
phase_accurate said:To make things more confusing:
A car's brake system is sometimes an amplifier as well. It uses the vacuum on the engine's air intake to amplify the force that you apply to the brake pedal.
Regards
Charles
it doesn't have to use power (vaccum). You are talking about power-assisted braking. There are (were?) plenty of non-power-assisted brake systems.
a better example is the hydrolic power jack you use to lift your car. It amplifies the force for sure, without any power assitance.
millwood said:
I disagree. A power jack is in this case the same as a torque wrench, because there is no gain. In total, I still have to exert the same amount of power to lift the car, but now it takes longer.
I believe an amplifier is only a controlled type of "valve", which allows a second power source to be controlled by a first power source.
If there is no second power source, but the device "transforms" the units of its input signal, it should be called a "converter"...
examples:
- power assisted braking is an amplifier, because engine power is propotionally added to the power inserted in the brake pedal.
- bycicle brakes are a converter, because they only transform lever length into force.
Regards,
Bouke
) it is a simple and easy to understand explanation of what's going on within all kind of amps. Bakmeel said:
yes, there is no gain in power (more precisely, energy): the gain in the car's potential is the same as the amount of energy you excert on the handle of the jack.
However, there is a huge gain of force: the force you put on the handle is probably 20 - 50 lb? yet, the jack lifts a car of 3000lb.
so in that sense, the jack amplified force (from 20lb to 3000lb). Kind like a voltage or current amplifier.
it does not amplify power / energy.
Power, voltage, pressure, it doesnt matter.
If you can supply an input to a system, that affects the output of said system by a relationship (be it linear, squared, whatever) then your system is an amplifier.
So a wrench IS NOT a force amplifer becuase force in = force out. Always. However, it IS a torque amplifier with a scaling function due to distance.
If that makes sense. Its all about how you describe the system in general.
y(x) = kh(x) where h(x) is an input function, y(x) is the output, and k is a dimensionless scaling factor. Byt his definition, y and h must have the same units. My definition of an amplifier could not allow force to amplify torque? Does this make sense?
If you can supply an input to a system, that affects the output of said system by a relationship (be it linear, squared, whatever) then your system is an amplifier.
So a wrench IS NOT a force amplifer becuase force in = force out. Always. However, it IS a torque amplifier with a scaling function due to distance.
If that makes sense. Its all about how you describe the system in general.
y(x) = kh(x) where h(x) is an input function, y(x) is the output, and k is a dimensionless scaling factor. Byt his definition, y and h must have the same units. My definition of an amplifier could not allow force to amplify torque? Does this make sense?
osey said:
there are two 'torques" on a wrench: one excerted by your hand, and another excerted by the bolt you are trying to unbolt,
.By definition, both much be equal. Otherwise the wrench will start to rotate faster and faster.
a wrench is just a form of lever. by placing the force strategically, you amplify the force.
Fi*Li=Fo*Lo, where (i) is input and (o) is output and F is the force and L the length.
so F*L is the torque, and the input and output is the same.
Fo=(Li/Lo)*Fi, where Li >>Lo, so Fo>>Li (>> means far greater).
thus, a wrench amplifies force, but not torque or energy (in a strict sense, there is no energy involved when the wrench is stationary).
a torque wrench is a wrench that will slip at set torque levels, or allows you to read out torque excerted by the wrench.
Hope it clarifies.
Absolutely correct. It is the one and only correct description of an amplifier.
However, our example of the wrench is in this perspective incorrect, because torque is a combination of units (Newton per Meter). I believe we can all agree that the torque in the wrench is the same at every place in the wrench, as millwood described. (Fi*Li=Fo*Lo, where (i) is input and (o) is output and F is the force and L the length.)
The force on the nut is greater than the force on my hand, so the wrench is amplifying my force. However, it also "divides" the length (amplifies with a fractional amplification factor), because the length from the center to the nut is smaller than center-to-hand. These two "amplifiers" cannot be seen apart from eachother.
So a wrench is two amplifiers in one... together the factors cancel eachother out, so the torque "amplification" is null.
please inspire me
Bouke
I see my wrench caused some stir here
It's a force amplifier. The torque is the same no matter how long the wrench is. We perceive it as a torque amplifier because we don't mind the extra distance we have to move our hands.
Now consider this; energy out = energy in.
Even for an audio amplifier, signal energy in + energy from the power supply = energy out (disregarding all losses here now). It doesn't matter for me if an amplifier has one or several energy sources. Take for example an audio amplifier fed with batteries, h(x) would include the batteries and have one input and one output. The output is stronger than the input, we say the gain is >1, at least if the amplifier is working
Many times we want to amplify just one parameter like the voltage by using a transformer, the force using a lever or similar. It's all amplifiers because they do what we want and we don't mind it at the loss of another parameter.
So, for me, an amplifier is a device amplifying a desired parameter. If this desired parameter is energy like in an audio amplifier I need to insert this energy into h(x) somehow.
Just rambling
It's a force amplifier. The torque is the same no matter how long the wrench is. We perceive it as a torque amplifier because we don't mind the extra distance we have to move our hands.
Now consider this; energy out = energy in.
Even for an audio amplifier, signal energy in + energy from the power supply = energy out (disregarding all losses here now). It doesn't matter for me if an amplifier has one or several energy sources. Take for example an audio amplifier fed with batteries, h(x) would include the batteries and have one input and one output. The output is stronger than the input, we say the gain is >1, at least if the amplifier is working
Many times we want to amplify just one parameter like the voltage by using a transformer, the force using a lever or similar. It's all amplifiers because they do what we want and we don't mind it at the loss of another parameter.
So, for me, an amplifier is a device amplifying a desired parameter. If this desired parameter is energy like in an audio amplifier I need to insert this energy into h(x) somehow.
Just rambling
I would say that the concept of an amplifier is not concerned about how the output is generated, but just purely assumes it will be. We are talking about an ideal model here.
Also dont get carried away by thinking about energy and amplification, they are really seperate entities. Sometimes one implies the other but not always. For example you could have an op amp circuit with an open loop voltage gain of 10000, but the energy supplied tot he output depends entirely on the current sourced. If used as a MOS gate bias the energy concerned would be tiny.
(Totally idiotic example I know)
We also dont really care about the fact the op amp ouput will blatently saturate with a few mV input difference, because rail voltages are the limits we impose ont he concept of our ideal amplifier.
Hope this is helping amp_man
Just as I anticipated in the beginning of this thread it has turned
into a rather philospohical discussion which could go on and on
forever. I really do wonder what amp_man_1's purpose with
the orginal question was.
I think we have to think about what question we are actually trying
to answer. Do we mean an amplifier in an engineering sense or
in a more mathematical system-theoretic sense? I think it is clear
from the discussion that some people take it in the first sense and
others take it in the second sense.
I assumed the question was about amplifiers in the engineering
sense, since this is an audio forum. From that perspective I still
think a wrench is a converter, not an amplifier, as I said earlier and
which also John Curl just said (and others too, previously). I also
think an amplifier should have an energy source and the input
signal in one way or another produces an output signal by using
energy from this source. I don't think it is necessary to get more
power out, however. We could have an amplifier stage that
amplifies voltage, for instance, but that is loaded with a very high
impedance like a JFET so that the output power is actually lower
than the input power. As somebody pointed out, we can take
the energy source into a mathematical description of an amplifier
if we wish, and describe its operation as a mathematical
function. Then is the question what requirements we have of
the amplifiers performance. Must it be a linear function of the
input signal? At least not in practice, since no amplifier is perfect.
We also have deliberatly non-linear amplifiers for certain purposes,
ie. log-amplifiers.
From a more mathematical system-theoretic perspective an
amplifier is typically just thought of as a gain block, a linear
function which scales a value by a constant. On this level of
abstraction energy sources and other practical matters are
typically not considered. Depending on "the user" non-linearities
may be allowed in the gain blocks or are kept as separate "boxes".
Typical electronic block diagrams are usually somewhere in
between these two, but more towards the system-theoretic
model, I would say.
I don't mean to present the above as "the truth", but as an
attempt to shed some light on what I think is a hidden confusion
in this discussion.
into a rather philospohical discussion which could go on and on
forever. I really do wonder what amp_man_1's purpose with
the orginal question was.
I think we have to think about what question we are actually trying
to answer. Do we mean an amplifier in an engineering sense or
in a more mathematical system-theoretic sense? I think it is clear
from the discussion that some people take it in the first sense and
others take it in the second sense.
I assumed the question was about amplifiers in the engineering
sense, since this is an audio forum. From that perspective I still
think a wrench is a converter, not an amplifier, as I said earlier and
which also John Curl just said (and others too, previously). I also
think an amplifier should have an energy source and the input
signal in one way or another produces an output signal by using
energy from this source. I don't think it is necessary to get more
power out, however. We could have an amplifier stage that
amplifies voltage, for instance, but that is loaded with a very high
impedance like a JFET so that the output power is actually lower
than the input power. As somebody pointed out, we can take
the energy source into a mathematical description of an amplifier
if we wish, and describe its operation as a mathematical
function. Then is the question what requirements we have of
the amplifiers performance. Must it be a linear function of the
input signal? At least not in practice, since no amplifier is perfect.
We also have deliberatly non-linear amplifiers for certain purposes,
ie. log-amplifiers.
From a more mathematical system-theoretic perspective an
amplifier is typically just thought of as a gain block, a linear
function which scales a value by a constant. On this level of
abstraction energy sources and other practical matters are
typically not considered. Depending on "the user" non-linearities
may be allowed in the gain blocks or are kept as separate "boxes".
Typical electronic block diagrams are usually somewhere in
between these two, but more towards the system-theoretic
model, I would say.
I don't mean to present the above as "the truth", but as an
attempt to shed some light on what I think is a hidden confusion
in this discussion.
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