Amplifier Definition and 560 Threads

An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is a circuit that has a power gain greater than one.An amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be categorized in different ways. One is by the frequency of the electronic signal being amplified. For example, audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz, and servo amplifiers and instrumentation amplifiers may work with very low frequencies down to direct current. Amplifiers can also be categorized by their physical placement in the signal chain; a preamplifier may precede other signal processing stages, for example. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Today most amplifiers use transistors.

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  1. L

    Build Simple Amplifier w/ Photodiode (No Op-Amp)

    Does anyone know how to build a simple amplifier to use with a photodiode that doesn't involve using an op-amp? Thanks.
  2. C

    Instrumentation Amplifier question

    Hi, Just a little question. The question wants me to obtain an expression for v0 as a function of v1, v2 and vcm, and show how the commom mode signal vcm can be canceled from the output by a proper adjustment of one of the resistors, R3, R4 or R5. To find v0, I have to apply the theory of...
  3. S

    Question regarding electronics (operation amplifier)

    I have my question,solution and doubt in the attachment that followed.Thanks for anybody that spend some time on this question.
  4. S

    Help - Amplifier Frequency Voltage relationship

    Can someone help me by describing why the output voltage drops away in an amplifier when the frequency is above or below the bandwidth?
  5. N

    Sine oscillator with unipolar operational amplifier

    I'm trying to make a sine wave oscillator with unipolar amplifiers, and all the circuits I find are for bipolar amplifiers. I've tried to modify the bipolar circuit, but it doesn’t work. Can anybody give an idea or a circuit? thank you for your attention.
  6. S

    Adding remote control volume to old amplifier.

    Found the site doing a Google search. Just need to know if this is possible. I have an old amplifier that does not have any remote control. I wondered if it would be possible to do something that will alow me to at least control the volume remotely. Any ideas. Thanx.
  7. A

    Fibre Optic Amplifier: What Is It?

    fibre optic amplifier?? anyone heard of fibre optic amplifier before or not?
  8. D

    Determining Bandwidth & Impedance of an Amplifier

    Ok I have this question that I am finding hard to answer. I understand that you guys won't answer homework questions but all I ask is a little point in the right direction. Heres the question anyway. An amplifier has an open-loop, gain of 10,000 and a bandwith of 2MHz. Its input and output...
  9. B

    Current amplifier needed? How? :=)

    Hi. I am building a power suply for a GM-tube tha needs a suply voltage of 550V. I am using a Cockroft-Walton voltage multiplyer. The problem I have is that it seems like I can't drain enough current from the circuit generating the squarewaves (the circuit on the picture). I have a peak to peak...
  10. Y

    Voltage Amplifier 72 on GRE: Negative Feedback Effects

    72 on GRE. In a voltage amplifier, which is the following is NOT usually a result of introducing negative feedback? a. Increased amplification b. Increased bandwidth c. Increased stability d. decreased distortion e. decreased voltage gain The answer is A. Can someone explain what...
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