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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2answers
104 views

High Input BJT Differential Amplifier

This is a basic differential amplifier. I want to modify it in order to have high input impedance (a few \$M\Omega\$ from DC to at least \$200~kHz\$) I thought about replacing the CE pair input with ...
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3answers
38 views

Can I replace a dual section capacitor in a tube amplifier design with two single capacitors?

I was planning on building this schematic, but found it hard to source their 20/20 dual section cap (C3/C4). Could I replace this with two single 20uF caps, or is it a dual-section for a reason?
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18 views

Static noise when using TDA2003 amp

I'm currently powering a couple of devices with an RQ-85B, amongst them a Tinker Board S (5V) and a TDA2003 module (12V), which outputs via an 8ohm speaker. These are all mounted in a large (...
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123 views

5V digital output to 24V

I'm sure it is a simple solution but I am new to this so please take it easy. I need to come up with something to convert a 5V digital output signal from a USB-1608G DAQ device with DIO to 24V ...
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2answers
162 views

Dominant Pole Approximation

I am studying Microelectronics by Behzad Razavi, 2nd Ed., where in the frequency response chapter it uses the "Dominant Pole Approximation" to find one of the poles easily from a quadratic denominator ...
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1answer
43 views

AC-Coupling blocking negative voltage values

This question is about the amplification of an electret microphone signal In this video: https://www.youtube.com/watch?v=SToBPCajwc0&t=615s He is using an AC-Coupling capacitor to block the DC ...
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3answers
272 views

Can we use a power amplifier (Class AB) in the inverter portion of a VFD?

I would like to float this idea of using a good (audio) power amplifier in the inverter stage of a sub 1KW VFD. How does this idea sound ? On the plus side, there is far less switching noise, since ...
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1answer
51 views

Audio Amplifier Clipping

I designed a PCB with the following audio amplifier on it: https://eu.mouser.com/datasheet/2/302/TFA9896_SDS-1381317.pdf According to the data sheet, the amplifier is able to deliver 2.1W RMS into an ...
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1answer
113 views

Common Emitter Stage BJT Amplifier with Early Effect Inclusion

How can I find Rin, Rout and Gm parameters of a BJT amplifier in common emitter stage without neglecting Early Effect? We have such homework and I couldn't find the exact same example in Behzad ...
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2answers
64 views

Opamp Current Sink + FET circuit help

I've been trying to figure out a design someone made for controlling a precision high current LED, and it's got me in a bit of a pickle. For the life of me, I can't figure out this exact op amp ...
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1answer
145 views

Driving Lights with Audio Amplifier

I'm working on a project where I want to have christmas lights (or LED strips if needed) react to music. In this case, the end goal is to have them pulse to the beats/bass of the music. There's a lot ...
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1answer
286 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
28 views

Problem in deriving Noise Figure for Cascaded systems

I am trying to derive Noise Figure of Cascaded System. I am making some conceptual mistake somewhere in derivation and getting wrong answer. Can any one please help me figure out where I am going ...
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0answers
27 views

Is it possible to implement a high-side current mirror with only NMOS FETs?

I need to implement a difference amplifier only using NMOS technology. I am struggling when trying to reference the voltage difference to ground. From my reading it looks like I need a high-side ...
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1answer
150 views

Buffer, amplify, filter, sample - In which order?

I'm trying get an audio signal from a high impedance source (guitar or mic) to an ADC. Some casual research suggested that I should filter my signal before amplifying it. My current mental design is:...
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2answers
47 views

Instrumentation Amplifier Reference Node - Integrator vs Buffer

When looking at INA topologies (lets take AD8220 for example) I see examples of integrator or buffered resistor dividers used. What are the disadvantages of using an integrator? Both typologies ...
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2answers
119 views

need circuit help with headphone amplifier 'thump' and other issues

This is my first post and I have a million questions. I hope some kind souls out there will not mind my noobness and be able to guide me any way they can. Firstly, I have a headphone amplifier ...
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1answer
101 views

High-voltage (HV) messing with my transimpedance amplifier circuit

I have a transimpedance amplifier circuit that takes 100kHz small current and gives the voltage output proportional to current amplitude. Everything works properly when nearby HV circuit is off. When ...
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1answer
222 views

Amplify Raspberry Pi Zero W Audio with 60s Tube amplifier circuit

First of all, thank you for taking a look at my question. Electronics is not my field of expertise, and I have found myself a bit stuck. I have been restoring some old 50s and 60s tube amplified ...
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1answer
122 views

Actuating Pencil To Draw Waveforms

I am looking to make a pencil whose tip moves to create a waveform as you move it across the paper.In essence, I want to be able to record a sound and then play the sound through the pencil whilst I ...
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2answers
2k views

how to derive the ac emitter resistance of transistor amplifier biasing?

I went through many textbooks and websites and I found out the derivation for AC resistance for diode which is \$r_d=26mV/I_{F}\$ where as for ac emitter resistance it is \$r_e=25mV/I_E\$ for which I ...
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2answers
178 views

Active Filter and Sine to Square Conversion Issues

Background: I am currently using a SparkFun Electret Microphone and am needing to both filter and amplify the signal before turning it into a square wave to be interpreted by a FPGA. The mic itself ...
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4answers
116 views

Nonlinearities in Fully Differential Op Amp

I am trying to construct an amplifier circuit using a fully differential op amp (THS4503) to interface with an ADC (ADS5232). I will be reading a 0-5V sensor, which needs to be converted to a 1Vpp ...
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1answer
512 views

Operational Amplifier Voltage Stabilization

I am wondering how an Operational amplifier stabilizes voltage ? Is it by negative feedback, if yes, then how ?
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1answer
20 views

Signal lines from transducer made common by op-amp

I am trying to amplify the difference between signal lines off of a Wheatstone bridge based force transducer. I've wired up an LM358N Op-Amp as shown below in a differential amplifier. With R1=R2=...
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2answers
103 views

What is the base current of a class ab amplifier with darlington pair configuration

I am trying to design a 3 stage amplifier using transistors, 2 pre-amp stages using class A configuration and an output stage class AB. I have built the class ab amplifier with a darlington ...
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0answers
154 views

How to make a guitar amp switcher?

So I'm trying to build a guitar amp switcher (and I don't really know what I'm doing =)). The idea is that guitar out is connected to X4 jack and then switched to either X1, X2 or X3 jack, which ...
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1answer
67 views

OpAmp resistor to ground in feedback loop

I am currently tasked with improving the design of an electrometer unit. It was NOT designed by an electrical, and there are some questionable design practices. My question is concerning the first ...
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0answers
26 views

Skype, windows 10, recorded videos, speakers [migrated]

I'm using the above and those who listen in on Skype are having problems hearing certain recorded videos. They can hear everything said on microphones at our location but when a video or music on ...
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1answer
177 views

Designing a Class A Audio Amplifier

I am currently working on a project where I am required to design a Class A Audio Amplifier using BJTs. The requirement of the amplifier is as follows: - Acquire a variable gain of at least 10 (Av >=...
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28 views

Common Collector Amplifier - Explanation?

I am new into electronics, and I dont get it how we find input and output impedance of Common-Collector Amplifier. I mean, I dont know what we are looking at when we are trying to find input and ...
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2answers
80 views

Fixing the Collector Current for a BJT amplifier

I am doing a design of a BJT amplifier with the voltage divider biasing. I am trying to set up my Q points in the DC analysis. Based on my notes from school and research online, I have set up the ...
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5answers
268 views

Actual reason why I have distortion in lower part of this square wave amplifier (level translator application)

I am designing a simple level translator using 2 transistors connected in series in LTSPICE simulator. I tried with one transistor but the output from the collector pin is 180 degree out of phase, as ...
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0answers
28 views

Finding transfer function of an amplifier

I would like to know if the transfer function i found is correct : TF = Vs/Vi = -(R-Rg)/(R+Rg) In my case Rf = R1 = R2 = R ( i just did not find the right schematics ) And V1 connected to V2 and ...
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30 views

bandpass filter design help

I need help designing a band pass filter that passes frequencies only between 500 and 1000Hz Attached is my filter that i made in multi-sim but for some reason nothing comes up on the oscilloscope. ...
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0answers
37 views

How does a high pass filter and a low pass filter work for an amp?

I'm researching how to incorporate treble and bass into an amp. X1 is for bass, X2 is for treble and X3 is for volume. Intuitively, for me, if a high pass filter only allows frequency above a ...
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1answer
73 views

500 mW RF amplifier for 170 MHz design

For a new project I need to build an RF amplifier for continuous-wave with about 500 mW (27dBm) output at 170 MHz. It doesn't need to transport data, it is only for measuring purpose. The input ...
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1answer
87 views

A question about selecting and using a fully differential amplifier

I have a unipolar but balanced/differential output transducer. The transducer outputs around +/-200mV and I want to amplify this with a gain of at least 10. The data acquisition board is also ...
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2answers
37 views

Difference between RS PRO 846-171 and INA125P for strain gauge amplification?

I am implementing a solution to read several strain gauges at once. Since I am using RS as my provider, I was about to buy the RS PRO 846-171 chip which is an amplifier specifically designed for ...
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1answer
87 views

Effect of changing current sense resistor value in amplifier circuit

I am trying to implement a current output amplifier circuit shown below. Current is measured across sense resistor Rs to adjust input voltage Vin. Gain: G = -Iout/Vin = R2/(Gain-of-IA1*R1*RS) The ...
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3answers
61 views

Gain-Bandwidth Confusion

Hi, I saw this online and I'm a bit confused why they chose B as the correct answer. My answer was: The DC voltage gain is 20dB, so -3dB frequency will occur at 17dB gain. 17dB in normal gain is 7....
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10answers
9k views

Amplification before tubes and transistors were invented

Telephones are older than vacuum tubes and of course transistors. How was signal amplification done? I mean the technology, not the details. EDIT Some additional informations that I should ...
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2answers
98 views

Accelerometer Sensor Output Impedance

I am looking into purchasing a TE 810M1 Accelerometer and had a question regarding the resistor's value for amplifying the sensors output. Here is a photo of the sensors electrical properties: The ...
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0answers
36 views

What gain can one expect from a single stage cascode amplifier biased with a cascode current source (45 nm CMOS technology)?

Is a gain of 135 good enough for a single cascode gain stage? Let's say I wanna put it within a larger CMOS operational amplifier later on. I am using 45 nm CMOS technology. Edit: I've included the ...
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2answers
85 views

How to amplify a 0-5V PWM Signal to 0-12V, 10A

I need a Power amplifier which amplifies a 0-5V Arduino-generated PWM Signal to a 0-12V Signal with 120W, for powering a ZVS induction heater. Linearity is not important because i can correct the ...
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1answer
48 views

Why is output voltage of current-to-voltage amplifier the same when input resistance is larger [closed]

Whenever we increase the resistance (imagine putting a bigger resistor in front of an amplifier) going into a current-to-voltage amplifier, why does the output voltage of that amplifier stay the same. ...
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1answer
171 views

Why CMRR degrades in instrumenation amplifier?

Why CMRR degrades in instrumentation amplifier when R3 (only the feedback resistor) is increased keeping all other resistances constant at a fixed value? What mathematical relationship links R3 and ...
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2answers
249 views

Please review this electric guitar buffer / volume / tone circuit

I have been tinkering with creating a MOSFET buffer circuit for my guitar to boost the high impedance output from the pickups to help drive the signal through long cables and pedal boards. This also ...
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1answer
73 views

Need help level shifting

I have an AC signal (500 - 1000Hz) 1v peak to peak that sweeps around 0v. The signal needs to be shifted to 0.5 -2V, a gain of 1.5... The power supply is +-10V. Just looking for someone to point me in ...
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1answer
215 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 ...