The real problem here is the large number of DIFFERENT uses and meanings attached to a single word. A QUICK FIX IS TO ADD descriptors to the word. So then we have "a MICROPHONE signal amplifier feeding an AUDIO POWER amplifier, delivering power to the speakers load.

 

@wayneh
I don't get it, do you think posting an image of energy transmission lines somehow proves something?

Without looking it up...give me the definition of 'power' and its expression, then maybe we can have a debate.

 

would it be possible to amplify a signal with this resistor circuit?


i put 'signal in/out' because i mean, if any works.

the theory question is basically, this circuit would present a voltage divider, so if a signal comes in at v2/v1, would this voltage result in a change in the voltage at v1/v2 , and in this configuration (or an alternate resistor organization) would it be possible to result in an amplification of the signal?

No the picture that you shared is not of an amplifier. Amplifier needs at least one transistor in the circuit.

 

Adding DC offset is not amplifying.

 

Really, actually amplifying requires an actual source of additional energy. AND, therfore, an active device, which is often a transistor, but could easily be a tunel diode, and used to be a vacuum tube of some type. BUT, in all cases of amplification, a device controlling the addition of external power.
"Wishing or wanting it to be different does not make it real," no matter what J.M. wants. ( J.M. was a sales person at a company where I was the engineer. )

 

@wayneh
I don't get it, do you think posting an image of energy transmission lines somehow proves something?

I was just making the point that energy can travel through a load, in this case the wires. They may not be the desired load, but they are a load.

 

Really, actually amplifying requires an actual source of additional energy. AND, therfore, an active device, which is often a transistor, but could easily be a tunel diode, and used to be a vacuum tube of some type. BUT, in all cases of amplification, a device controlling the addition of external power.
"Wishing or wanting it to be different does not make it real," no matter what J.M. wants. ( J.M. was a sales person at a company where I was the engineer. )

What about the following?
The input voltage Vin is converted to light (LED) which lights up a light sensitive resistor (LDR) which is part of a grounded resistor chain (at least two parts in total) which is connected to a "DC supply voltage".
Is it possible that the voltage across the LDR is larger than Vin?

 

I was just making the point that energy can travel through a load, in this case the wires. They may not be the desired load, but they are a load.

Fine...but I didn't say that energy doesn't flow through a load, I said "power" doesn't flow through a load.

 

Fine...but I didn't say that energy doesn't flow through a load, I said "power" doesn't flow through a load.

They're literally called "power lines". Dividing by time to get the rate of energy transfer doesn't change anything.

 

What about the following?
The input voltage Vin is converted to light (LED) which lights up a light sensitive resistor (LDR) which is part of a grounded resistor chain (at least two parts in total) which is connected to a "DC supply voltage".
Is it possible that the voltage across the LDR is larger than Vin?

CERTAINLY the combination of an LED andan LSR constitutes "an active device", although not what I had been considering.

 

They're literally called "power lines". Dividing by time to get the rate of energy transfer doesn't change anything.

It does change something because power and energy are two entirely different things.

Energy is the ability to do work, and power is the rate at which work is done by energy.

 

It does change something because power and energy are two entirely different things.

Energy is the ability to do work, and power is the rate at which work is done by energy.

Similar to the word "amplify", POWERis routinely used incorrectly. This misuse tends to confuse the understanding of the close definition.

 

What about the following?
The input voltage Vin is converted to light (LED) which lights up a light sensitive resistor (LDR) which is part of a grounded resistor chain (at least two parts in total) which is connected to a "DC supply voltage".
Is it possible that the voltage across the LDR is larger than Vin?

That is a very interesting thought! I can't actually see a reason why this should not work, though no doubt someone will come in to puncture my bubble!

And I'm not sure I would agree with Mister Bill that this constitutes an 'active device'. How is such a thing correctly defined? Ah, philosophy...

 

................
And I'm not sure I would agree with Mister Bill that this constitutes an 'active device'. How is such a thing correctly defined? Ah, philosophy...

Yes, that is a good question - how to disriminate between passive and active parts.
I think,there is no doubt that a BJT must be considered as "active".
On the other hand - a BJT is not more than a specific combination of two pn junctions.
Hence, why shouldn´t we treat an LED/LDR combination also not as an active device?

 

hi
AAC Article link.
E
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-1/active-versus-passive-devices/

 

You can amplify a signal without active components using a transformer.

Yes, it is possible to use a transformer to increase the amplitude of a signal. But one must define the frequency(s) of the signal in question.

 

There needs to be an understanding that "negative resistance", as it has been described here, IS ALWAYS INTENTIONAL. It is not accidental, except in some cases of insulation breakdown.

Maybe not accidental, but certainly *not* intentional.

Another example is the input of a switching regulator with a constant load.
As the regulator input voltage increases, the input current goes down (since the power output and thus the power input stay essentially constant).

As many young power system designers discover (the hard way), switching regulators in series can produce *interesting* effects. Turns out that many control loops are not compensated for a negative-resistance load.

ak

 

You can amplify a signal without active components using a transformer.

You can amplify (not really the right word) one aspect of a signal using a transformer. Voltage or current, pick any 1.

ak

 

You can amplify power with the right type of transformer(s).
https://vtechworks.lib.vt.edu/serve.../90408f3c-beb5-42d6-b583-1dc69d27c441/content

 

When I was in college we discussed op-amp circuits with a gain of less than 1, soooo......