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Questions tagged [amplifier]

An amplifier can be used to adapt the range of the signal to a requirement, to make it more robust for transmission, or to satisfy interface requirement (like input/output impedance)

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154 views

Inverting OpAmp with voltage divider in feedback loop

Last week I was looking for a programmable gain amplifier (PGA) with high gains (> 100V/V) and low noise. As far as I know most of the PGA integrated circuits out there are just (inverting) amplifier ...
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1answer
63 views

Amplifying milli Volts to Volts

I am currently using a KE-25 oxygen sensor which is galvano microcell type oxygen sensor which doesn't require a power supply to sense oxygen level in the environment. Depending on the concentration ...
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2answers
103 views

Will this receiver work?

I'm just a beginner, trying to understand an antennas and transistors as an amplifier, I'm studying, please correct me. Here we have a voltage source, PNP bipolar transistor emitter-base-collector ...
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1answer
28 views

I need to find Vin max(Common Mode) and min(common mode) for given circuit.

please let me know how i can proceed with this circuit
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2answers
65 views

Why voltage source has been connected via inductor at the output of LNA?

I have been reviewing the schematics of LoRaWAN Gateway designed by Microchip (Page 48). The output of the LNA has been connected to voltage source via inductor. ...
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3answers
109 views

Amplifying a pulsed current

I need to pulse a current through a coil, to create relatively short magnetic pulses. I would like to know if I can use a function generator as the source of the pulses and amplify the current that ...
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1answer
144 views

Is there any difference between AD620 vs INA128?

I'm trying to make an EMG sensor. I've found some tutorials, for example, DIY muscle sensor/EMG circuit for a microcontroller, but my main question is can I make an EMG sensor using AD620 instead of ...
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1answer
63 views

Need help extracting line out signal from car radio

I'm trying to extract audio signal from my car stereo and use it as an input to my external amp. The place I want to get it from is marked in red in this picture: I used the IC31-34 pin12 to get the ...
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2answers
82 views

Current feedback amplifier input structure

This is an input stage of some obsolete CFA (current feedback amplifier): Current feedback amplifier is a transimpedance amplifier, which converts current signal at its input into voltage signal at ...
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4answers
138 views

Under what circumstances would the large internal input resistance of an actual op amp affect circuit operation?

I was able to find a lot about why the input resistance is high and basically infinite. I understand that the input resistance is high so that it doesn't become a load on the signal. I also know that ...
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3answers
170 views

How to wire headphone switch correctly in audio amp (LM4875) circuit?

I'm working on a circuit for a small audio device and I'm a bit confused about the headphone jack wiring, I hope someone can shed me some light. I'm using the LM4875 because I have a speaker and a ...
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1answer
119 views

Loudspeaker volume issue

I am building a microcontroller based circuit that generates some sound out of a loudspeaker. Basic problem: Not enough volume out of loudspeaker Strange stuff: Volume is louder if I use a LM386 ...
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4answers
51 views

How will an audio power amplifier output voltage behave when loaded?

If an audio power amplifier would power a 8 Ohm speaker through its proper(?) output and if the volume knob is set such that the amplifier outputs 8Vrms 440Hz sine wave across the speaker leads the ...
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1answer
60 views

Voltage Amplifier using Op Amp 741 [duplicate]

I am trying to build an amplifier using op amp 741. But I am failing to build it on breadboard. I am connecting the positive end of a 9 V battery to pin 7 and negative end to pin 4. As per my ...
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1answer
70 views

What options are available for measuring grounded thermocouples?

I'm using 4 MAX31855 ICs to measure 4 K-type thermocouples and realized that 2 of my thermocouples have grounded junctions; I simultaneously also realized the MAX31855 is stated to not support ...
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3answers
151 views

Why do tube amplifiers have such (relatively) small reservior capacitors?

In learning about guitar amps, I've been studying the schematics for solid state and tube amplifiers, and I found a pattern that I've never seen an explanation for. If you consider any of the main ...
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1answer
84 views

Problem encountered while amplifying load cell signal with LM358

I have an S-type load cell to measure weight up to 100 Kg. Its datasheet mentions 3mV/V against full range and excitation voltage. When no weight is applied, the voltage is 9.9 mV (Excitation is 10 V)...
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79 views

Intuition behind transit angle of a klystron

What I understand is that the electrons get attracted to the anode and during their passage through the buncher gap, they regroup into bunches due to differing potentials imposed on different ...
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2answers
181 views

Which is broken, the amp or the driver of this subwoofer?

My subwoofer (with an internal amp) is showing difficulty reproducing low frequency sounds (sine 30Hz ~ 70Hz). As I lower the frequency, around 70Hz, I start hearing very slight distortion (hint of ...
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2answers
31 views

Does Differential Amplifier Emitter behave as ground in AC-analysis?

I am trying to solve various differential-amplifier homework problems for which I have the solution to study. For the simplicity of most problems we are able to neglect base-currents. Moreover, it ...
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0answers
35 views

Maximum mid-band gain of s.s. model MOSFET amplifier?

Schematics I need to find the maximum possible gain for this NMOS cascode circuit. Here is the s.s. model: Work I used nodal-matrix analysis (basis is KCL) to find the gain (\$A_v\$): $$ \...
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0answers
55 views

What is the reason for high frequency noise when amplifier is powered with battery?

Hi I made a small headphone amp and powered it using lipo battery.voltage is stepped up to 5v.everything is working with direct supply (ie., while charging battery)but as soon as I unplug the charger ,...
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1answer
35 views

How to calculate gain of opamp with Max446 chip?

I just wondering how do you calculate the gain of the amplifier in a circuit like this: I am familiar with gain calculation on non-inverting and inverting opamp but am having trouble with this. Any ...
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1answer
61 views

What's this amplifier filter configuration?

I've come across an audio amplifier circuit that contains this following configuration: I recognize R1,C1, and R3 to be part of a first order high pass filter, but I'm not sure what C2 and R2 are for....
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2answers
57 views

rf amplifier saturation when input chirp

I am trying to generate an 11 MHz pulsed chirp signal with center frequency of 4 GHz at a power level of +10 dBm. I have an arbitrary waveform generator that can generate the correct chirp signal, but ...
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0answers
64 views

Crackling sounds when both speakers are connected?

I have finished my amplifier using the LA4597 chip following the schematic below. So far everything's working fine. However, I noticed something. Some songs crackle the speakers (probably because of ...
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1answer
70 views

Powering an amplifier with lower voltage?

This amplifier uses a 24V 700mA power supply (more details here): Question: The amplifier currently drives an 8Ω speaker, a comment from my other question says that to be able to drive a 4Ω speaker, ...
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1answer
59 views

Amp for tweeter in bi-amping

I gonna make some 2-speakers Bluetooth PA system, and I chose bi-amping way with active crossover for do it. I have an 60W amp (battery limits) for my woofer. Skipping all the problems on my road to ...
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1answer
165 views

Zener diode at inverter op amp's output

I would like to know what would be the effect of placing a Zener diode between the op amp's output and the actual output of the circuit like shown in the schematic. The Zener should be of 5 V. ...
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3answers
186 views

Guitar pedal input stage buffer

In the below schematic for the Tube Screamer guitar pedal input buffer, there is a 1k resistor (R1) after the coupling capacitor (C1). What is the purpose of this resistor? It has no effect on the DC ...
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1answer
26 views

Diifference between INA827AIDGK & INA827AIDGKR

Whats the difference between the same package of the IC INA827 - INA827AIDGK vs INA827AIDGKR? The datasheet makes no mention of any differences. Except in in.element14.com where INA827AIDGK is ...
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1answer
180 views

Will this 5-watt audio amplifier work for my speakers?

I found this schematic and it says the speaker used is 5W and 8Ω. However, the speaker I have is a 5W and 3.2Ω. Will it work? What are the conditions? And what would be the effects? And if it's okay, ...
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2answers
98 views

Voltage amplification

I have a output of .03v from my logic gate but i need it to be 5v to enable my dc motor. How can i amplify it into 5v using a transistor?
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2answers
61 views

Confusion with meaning of low and high impedance sensor

Regarding an excerpt from this text: Some accelerometers feature an integrated electronic circuit which converts the high impedance charge output into a low impedance voltage signal. What is ...
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3answers
99 views

Audio power amplifiers

Is an audio power amplifier (not a preamp), commonly used in the high-end home sound systems of audiophiles, a voltage-controlled voltage-source?
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2answers
63 views

Help me understand what happens with the circuit when an AC signal is applied

Consider this circuit. Transistor is 2N2222A. Ic is chosen to be 10 mA. Hfe is 225 for that current. Resistors are calculated to have Vbe = 0.7V and Vc = 4.5V. I am trying to understand what happens ...
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1answer
354 views

Biasing high frequency BJT cascode amplifier

So far, no one in the course has gotten both primary spec: 14.125 (with 1 V/V swing either way) nor 3dB-bandwidth of 500kHz to 20MHz using the 2N4427 (datasheet). Vcc = 9V I_CQ = 10mA-15mA I have ...
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2answers
141 views

Stereo or bridged mono? (LA4597)

I have a stereo amp (LA4597) and is currently wired in a standard stereo circuit. Recently, I read an updated answer from one of my questions stating that wiring the amp in bridged mode doubles the ...
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1answer
38 views

DC and low signal Analysis of Common Source Amplifier: wrong drain current and amplification?

For a Coursera test I need to analyze a common source amplifier: I need to calculate the DC gate voltage - easy: -2.3077 drain current Id - should be easy but the results are wrong. I use this ...
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1answer
150 views

Amplifier Noisy Output (LA4597)

I have a problem with my amplifier circuit (LA4597). I tested it (12V). It turns on and the speakers and fine and silent. But when I try to add an audio source (RCA) within the circuit, the speakers ...
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4answers
2k views

Why put a step-down transformer after a vacuum tube in an a valve amplifier?

I'm researching valve amplifiers. I found this schematic for one: So the input is amplified by the first valve, and then the amplified signal is amplified again by the second valve, right? My ...
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2answers
58 views

Isolation Amplifier Gain Problem

I'm having a little trouble with an isolation amplifier. I'm using an HCPL-7800 isolation amplifier, in the circuit format provided by the manufacturer as a test circuit, and feeding it low voltage DC ...
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0answers
62 views

Audio power amplifier circuit explaination

This circuit: My goal is to modify this circuit to operate in DC mode. Got this circuit on the web, but there is some part of it that I still don't get how it operates. T4/T5 is an adjustable ...
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1answer
64 views

Equivalent noise resistance(s) - 2 stage amplifier

I came across this question in my textbook: The first stage of a 2-stage amplifier has a voltage gain of \$150\$, an input resistance of \$1500 \Omega\$, an equivalent noise resistance of \$700 ...
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1answer
51 views

What is the relationship between an amplifier's step input and the frequency sweep response?

What is the relationship between step input response and the frequency response of a system such as an amplifier? I see similarities between the step input response of an amplifier and the frequency ...
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1answer
56 views

How can I calculate power consumption of the amplifier from its datasheet?

In datasheet of the transistor, CGHV40100, I could not find the power consumption of its. How can I calculate the power consumption? Datasheet of the CGHV40100
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1answer
83 views

Output voltage in MOS cascode amplifier

I'll give a background to my main question:- In a simple NMOS as shown, while constructing the small signal model of the MOSFET, when there is no resistance between Vdd and drain, NMOS is modeled ...
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2answers
71 views

Confusion with the gain concept of an amplifier

Before asking my question I want to briefly write about the basic meaning of the power gain. Below is a model of an amplifier: It shows the source input and amplifier output from left to right. ...
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2answers
152 views

How do coupling capacitors in transistor not affect biasing?

I understand the usefulness of the capacitors in an amplifier circuit but i dont understand why we use one at the input? and how does this not affect the biasing if it removes the dc voltage? Thanks.
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5answers
2k views

Why are two stages used for an instrumentation amplifier?

When we have a two-stage instrumentation amplifier, such as the following. Why do we need the first stage of the two Operational Amplifiers? Couldn't we just input V1 and V2 into the differential ...