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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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How to analyze Bipolar Junction Transistor circuit?

I have been reading about BJTs and their ability to work as inverting voltage amplifiers. The circuit included in the notes I am following is: In the notes, it is explained that with a simple ...
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63 views

How to design a circuit starting from a block diagram?

I am struggling with the following self-study problem, taken from The Analysis and Design of Linear Circuits (8th edition). There are two things that shock me from this problem. We need to get a ...
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1answer
82 views

Reasons for choosing a transistor instead of an op-amp as a buffer

I have often seen circuits for guitar pedals that use an emitter-follower configuration as the input and output buffer (see example below). If an op-amp can provide a greater input impedance / lower ...
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3answers
73 views

Differential to single ended audio signal

I'm working on an interface that will be connected instead of a speaker, input of my interface is differential, and output is single ended. I'm using the following schematics : R3 is the load to ...
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2answers
52 views

Why does these capacitances have no effect on the output of this amplifier?

Below shows a piezoelectric sensor connected to a charge amplifier: The text claims that the output voltage Uout is to a good approximation only charge q which is going to be measured divided by the ...
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52 views

How do i drop voltage in series?

I have a 12v PSU output voltage that uses around 9A, i need to decrease this voltage to 11v but keep the amperage the same, any ideas? thanks
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1answer
27 views

What happens when the DC supply of this common gate amplifier is switched off?

The Vin in this case is a 200mV peak to peak sine wave signal. what happens to the gain of the amplifier when the DC supply of 10V is switched off?
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23 views

PWM Comparator types for Class D

I've started simulating a Class D amp, but it seems the MAX999 (I saw recommended elsewhere on this site) isn't working. Could anyone point me in the direction of why? I swapped in an LM311 which ...
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1answer
80 views

Designing two stage CE amplifier with negative feedback [on hold]

I'm trying to design two stage ce amplifier with negative feedback using 2n2222 transistors. The circuit must have certain voltage gain, Rin, Rout, Vcc, low and high frequency filter. This is the ...
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33 views

Circuit Design for ECG amplification

I've come across this circuit diagram in Biomedical Digital Signal Processing by Willis J Tompkins and in the description it says it is to do with ECG amplification. The input to the non-inverting ...
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3answers
177 views

Understanding Operational Transconductance Amplifiers

I understand the high-level function of OTAs, that they provide an output current proportional to an input voltage. But what I don't understand, and what I can't seem to find any information on online,...
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123 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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56 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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86 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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51 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
96 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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37 views

about low distortion amplifier BJT 2 transistor gain stage with shunt feedback [closed]

I need introduction about why we need low distortion amplifier?
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1answer
81 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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49 views

The function of a Resistor on an Amplifier power + [closed]

Good Day all, Am a bit confused About Something, i have this pair of amp built with TEA2025b IC which runs on 12v 1.5A, and am using a 12v 2A Transformer, but one of the circuit has a resistor in ...
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59 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
72 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
112 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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48 views

Amplification by superposition?

Let’s say I want to use an amplifier to generate a pulsed current of amplitude I_o in a load but my amplifier can only supply a pulse of amplitude I_o/2. Is there a way to introduce a delay of the ...
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3answers
51 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
67 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
42 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
48 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
35 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
138 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
44 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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68 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
156 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
25 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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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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51 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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34 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
58 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
52 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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63 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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39 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
41 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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107 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
73 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
144 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
89 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
46 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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91 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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39 views

Pulsed a magnetic field, what would be a suitable way to pulse a high current?

I would like to pulse a magnetic flux of up to 25 mT, for an experiment. I would like the pulses to be as short as possible 60-70 ns. I have a solenoid, 10 cm in length, 5 cm diameter with 7 turns, ...