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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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48 views

Output impedance of a series shunt feedback amplifier

I am trying to find the output impedance of a series shunt feedback amplifier by converting it to a two port network. I know the input impedance: Ri=ri*(1+A.β) But I dont know how I should find ...
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0answers
63 views

Why only odd harmonics after signal is amplified? *Plots inside*

Why do I get only odd harmonics appearing? This not only happens at saturation of the transfer curve, but also in the linear portion of the curve. I make an input signal and the power of this will ...
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1answer
38 views

Lower noise in biased op amp

I have a circuit similar to this. I’m trying to lower my noise under 60 Hz. Using pspice I keep finding that I need a very large resistor for R5, like 50 gigs but in practice this is not giving me the ...
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1answer
50 views

Amplifying Current from 0-20mA to 3A

I would like to drive a pump with a PLC. The PLC generates analog output signal of 0-10V with 0-20mA and the pump runs at the same voltage but 3A current. Is there any solution to this problem? Thank ...
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4answers
60 views

Input and Output impedances of Current and Voltage Amplifiers

I read that Voltage Amplifier have high input impedance and low output impedance, and Current Amplifier have low input impedance and high output impedance. If this is true what is reason for this as I ...
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0answers
49 views

How does speaker in “ROBOCOPP B A S U Ealarm SOS Personal Alarm” works?

I was working on a project which required producing a sound with more than 125 DBs...then I found this device in market which claims of producing 130DBs although to my knowledge it produces around ...
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0answers
45 views

What component is best for a voltage follower amp (specs given in question)?

I am wanting an op amp that can act as a voltage follower. Essentially the project is speed control of a motor and since PWM is being used, the following circuit was going to be implemented: ...
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1answer
33 views

Cap in Series with a DAC Reverse Current

I'm using a 8-bit DAC: (DAC5311IDCKR) to generate a 1.5V Amplitude sine wave with a 3.5VDC offset. I've put high-pass RC filter across it shown below to block DC so that it becomes AC. I understand ...
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0answers
66 views

Repurposing or obtaining a cheap audio signal amplifier for school physics lab

I teach highschool physics, and want to connect my smartphone (LG V20) to a Chladni plate (vibrating plate for studying interference patterns in sound in solids). I have successfully done this by ...
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4answers
126 views

What is the purpose of using the transistor in the circuit?

Current sensor using an instrumentation amplifier: Image source: Texas Instruments INA139, INA169 High-Side Measurement Current Shunt Monitor, Typical Application Circuit (datasheet page 1) Could ...
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1answer
33 views

Triangular wave amplification

I've made a triangular wave by ICL8038 and it works perfectly at 15kHz with 15Vpp. I need to drive a 4 ohm load by that triangular wave. Could you please show me a solution/circuit to do that?
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30 views

Calculating the efficiency of an audio amplifier

I'm looking at the PAM8406 Class-D/Class-AB amplifier and I'm not seeing the efficiency for a 2Ω load in Class-AB mode. The use case for the amplifier is driving mid-range/mid-bass speakers for ...
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2answers
26 views

Adding a potentiometer to an LM4910 as a volume control

Can someone tell me where I need to place a potentiometer to control the volume in this LM4910 amplifier circuit? Does the shutdown pin need a pull up resistor to enable the IC?
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1answer
46 views

40kHz Ultrasonic transducer - datasheet gives capacitive load at 1kHz what is it at 40kHz?

A hopefully simple question, the datasheet for a 25kHz Ultrasonic transducer gives the capacitance load at 1kHz what is it at 25kHz? I've been calculating the current using I = fCVpp where f is ...
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0answers
20 views

Project involving the Texas Instruments TAS5720 amplifier - Power Requirements

The Google Home Mini uses the TAS5720 amplifier with a power supply which delivers 5V DC, 1.8A. From the datasheet it looks like this amplifier can deliver 20 W at 0.15% THD Continuous into 19 V / 4 Ω....
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0answers
33 views

Where to add RF power amplifier [closed]

I am trying to make a SX1262 circuit using this schematic, I have the values for the passives from the BOM already. But I do not understand the schematic very much, where would I place an rf amplifier ...
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0answers
24 views

Low power headphone amplifier circuit [closed]

does anyone know schematics of a headphone amplifier, I have a mono signal from a microcontroller and I need to amplify the signal to a headphone. the device is 2000mah 3.7 li-po battery powered. ...
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1answer
24 views

How to split mono signal to sterio siginal of AD9833 Sin wave generator?

I am sorry that I am not well aware in audio amplifiers, that's why I am asking this question maybe it's my stupidity. I have an AD9833 sin wave generator, I need to connect the AD9833's output to ...
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1answer
45 views

How to amplify a signal for piezo transducer from 1 Vpp to 200 Vpp at 400 kHz and 500 pF load

I'm a researcher working with phased ultrasonic transducer arrays. I need to amplify a sine wave at 400 kHz and 1 Vpp to 200 Vpp. It has a capacitive load of 500 pF. I'm little ...
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1answer
25 views

Capacitance to useful signal conversion

Working on a project, where we need to measure the change in capacitance(capacitance change roughly from 0.5 pF at the start, to 20 pF at the end of the measurement). On the variable cap, only the ...
3
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2answers
99 views

Confusion between the necessity of maximum voltage and maximum power transfer

This is a conceptual question therefore I want to ask with an example. I'm wondering in which cases impedance matching is used. For example, if one has a sensor which can be modeled as voltage ...
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0answers
34 views

Audio Amplifier Power Usage

I'm looking to add an audio amplifier to a circuit, in this case the TPA0211 in 5V mode for a full 2W of output. My rather dumb question is this: I should expect at least 400mA of current draw from ...
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0answers
43 views

Single-ended to differential audio preamplifier for low impedance power amplifier [closed]

I'm searching for a suitable IC solution to handle four audio 4V single-ended input signals and get for each of them, a differential output signal (with the possibility to have a gain) to drive an OEM ...
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1answer
52 views

Improving Power Amplifier - Digital Bias current set

In the following power amplifier: the MOS bias current is set by VR2. T4 acts as a temperature balance. The ensemble R15, RV2, D5, T4, T5, R14 act as a current source. VR1 act as offset adjustment....
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1answer
36 views

Equivalent power BJT transistor 2sa758 and 2sc898 for Sansui au 6600 Amplifier

I am restoring my Sansui au6600, at the moment I am recapping it, however I will have to replace the two final power transistors for the left channel which I found out to be faulty. The parts listed ...
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1answer
42 views

Compensated vs uncompensated Op Amps [closed]

What are the advantages/disadvantages of compensated and uncompensated op amps? Thank you in advance.
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3answers
74 views

Difference between two integrator circuits

What is the difference between the two integrator circuits? They are used in an amplifier with feedback. There's heaps of information online about the one on the right but not so much about the one on ...
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1answer
111 views

Common Emitter Amplifier design problem - seeking quick solutions updated

Looking for a quick check of solutions to the below problem. Design requirements: AC gain of G = -10 Output impedance of R = 4.7 kΩ T1 is 2N3904 npn transistor with β = 100 and base-emitter voltage ...
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1answer
44 views

The proper way of using gm/Id plot for designing an amplifier or OTA

For any design of an amplifier or OTA, we are given the specs which we need to achieve including: Gain UGBW or 3db BW Slew rate Power consumption Phase Margin Load capacitance I would like to ...
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1answer
60 views

Large ac input class AB biasing

I'm trying to bias the following circuit to power an 8 ohm speaker with an 8Vptp output. The following are the calculations I've done to get this current setup but the output is only good up to 1Vptp ...
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2answers
156 views

Gain of Non-Inverting Amplifier Does Not vary with Resistor Values

I am trying to build a non-inverting amplifier using a LM7171 op amp, and I am implementing it with potentiometers as Rf and R2 so that I can smoothly control the gain of the amplifier (and easily ...
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1answer
87 views

Common emitter amplifier with load resistance

I can't seem to grasp how to calculate the values for a common emitter with a load resistance, to cascade an amplifier in multiple stages. I'm trying to obtain an 8.5-9Vptp output from a 12V supply ...
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1answer
53 views

Need help understanding how this decoder IC & differential amplifier circuit works

I need help to better understand differential amplifiers, when interfaced with an decoder IC. For the circuit below, which is from the reference design here: It shows a mono differential amplifier (...
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2answers
55 views

Confused on voltage potential

I’ve been doing much research the last couple of days about electricity. I have a pretty good understanding of Watts, Joules, Coulombs, Amperes, Ohms, and I know Ohms law finding voltage and all and I ...
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0answers
43 views

Tea2025 not loud enough

simulate this circuit – Schematic created using CircuitLab I built an amplifier with TEA2025 but the output is not satisfactorily loud enough. I measured the output voltage to be between 2....
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1answer
68 views

Cascading Op Amps for Phototransistor Output Conditioning

I am working on a project in which I am using an IR phototransistor to detect changing low levels of light. Currently with very high load resistance I can get a reading of 40-60 mV but I would like to ...
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2answers
1k views

Single supply non-inverting amplifier using op amp

I'm working on building a distortion guitar effect pedal for an analog electronics class I'm taking. I am struggling with building an amplifying circuit using an op amp (we just began learning about ...
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1answer
40 views

How to find the Common Mode Rejection Ratio of this circuit?

My attempt was like, by using the formula, I can get, \$CMMR=\frac{\sqrt{2\cdot4\cdot8\cdot5\cdot10^{-6}}\cdot44000\cdot2}{x}\$ For the denominator, I used both 10% and 20%, but all the finals were ...
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1answer
48 views

BJT Cascade Difference Amplifier Exercise

I need help with the exercise. The questions: Add or Design Components to have a current source I=2 mA at the picture. Draw equivalent small signal,low frequency model. Find Ai, Zo, Zi. If ...
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2answers
58 views

How can I get a loud noise out of a 15mm piezo disc?

I need to get an as loud as possible noise out of a 15mm piezo disc, using only the 3V from Arduino. I know I will have to make some sort of amplifier circuit, and I have attempted to make a basic ...
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1answer
75 views

2N2222 transistor datasheet saturation current

I am designing a 2N2222 transistor common emitter voltage-divider amplifier. Using 9V for the power supply and trying to make the loadline to determine Q. How do I determine the sauration point ...
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1answer
50 views

Input impedance of differential amplifier

Can someone please explain to me, how I should look at the input impedance of the opamps, seen through the voltage \$V_1 V_2\$? I have two questions on the differential amplifier: Why doesn't the ...
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1answer
31 views

Harmonic detection using lock-in amplifier

Can a third harmonic of a signal be detected using a lock-in amplifier under the same parameters fixed for collecting the fundamental or the parameters needs to be adjusted.Here by parameters I mean ...
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2answers
2k views

What property of a BJT transistor makes it an amplifier?

I know how we can amplify a given signal using BJT transistors by biasing them. But I would like to know what is that crux property which enables BJT transistor to act like an amplifier. Is it the ...
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0answers
91 views

LM358 Headphone Amplifier Oscillations

I'm trying to build a very simple headphone amplifier for my bass guitar. The bass has a built-in amplifier, meaning that unity-gain is sufficient for my amplifier, I essentially only need a voltage ...
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2answers
86 views

Calculating base-emitter current of a BJT, with emitter connected to ground (no resistor)

Much like the circuit above, most BJT amplifiers use an emitter degeneration resistor to stabilise the bias. It's relatively straightforward to calculate the base and collector quiescent currents. I ...
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0answers
23 views

is the gain for this differential bjt pair correct?

I'm referring to the diff pair consisting of Q1 and Q2, ignoring the rest of the circuit for now. I've attached a pic of my diff pair small signal model and what I calculated for the small signal gain....
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1answer
52 views

Supplying two IC within a circuit with different voltage range (1.8v to 3.6v) and ( 4v to 5v) with battery power [closed]

We are designing a circuit that has two ICs with different supply range. it will use micro batteries as supply unit. What is the efficient way to feed two ICs together and waste minimum energy. Of ...
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0answers
32 views

Gain and output impedance in a differential amplifier

When looking at a differential amplifier: Why does gain increase when the output impedance is increased? For example, replacing a differential amplifier biased with resistors for an active load (...
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1answer
98 views

Identify of Amplifier class?

I want to build an amplifier. I got a circuit diagram from a website, Amplificador Monofónico de 250 Vatios Cuasicomplementario. I want to know the class of this amplifier.