Questions tagged [amplifier]

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

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Phase shift near saturation mitigation in input stage amplifier -- How does this work, why does this work?

I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer. Apologies for the quality... this is the best scan I could find. The design is furnished with the ...
Evan's user avatar
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Active load role on this circuit and possible uses

simulate this circuit – Schematic created using CircuitLab I came with this circuit to know how an active load can improve it, I still can't finish to understand the role of active loads. The ...
tac's user avatar
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I have a question about the datasheet for AD8330 VGA (variable gain amplifier)

I don't have much experience reading datasheets. I was reading the datasheet for AD8330 VGA. I did not understand what the difference is between VDBS and VMAG. Can someone elaborate on that? It's ...
Analog's user avatar
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D-Class Amplifier Design Verification

I have an internship coming up working with comparators and amplifiers, so I wanted to take on a side project involving both of those components. Designing a D-Class amplifier seemed like a great way ...
Yet Another Michael's user avatar
3 votes
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Tips on Building An Analog VCO

I am attempting to build an analog VCO. Many of the resources I see online implement a 555 timer, but I am trying to avoid that, solely for the sake of learning how to do this in purely analog. Here ...
Chris Lallo's user avatar
3 votes
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159 views

How to calculate an rf amplifier stage

I changed the LC tank of the circuit below for operation in the 2m ham radio band (144-146MHz, I'm a licenced Class A Ham). Now I'd like to add an amplifier stage to increase the output by about 30dB. ...
Laurin's user avatar
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What is the easiest way to change the polarity of a transistor based simple amplifier?

I would like to amplify signals from a silicon photomultiplier, which is an array of many small avalanche photodiodes (APDs). When one or a few APDs get hit by a photon, a small current will flow ...
Jing's user avatar
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An amplifier that can output 40..50 V at around 15 MHz

I'm trying to build something to amplify a signal to produce a 40 V output at 15 MHz. I haven't been successful in finding an opamp that can both output at these voltages while also not dropping the ...
coolyfrost's user avatar
3 votes
1 answer
179 views

How to change the volume of one pair of speakers

I have two speakers outputs on my old technics SU V560 amp that I used for years to drive wharfedale E20 speakers that I use in the living room. The amp has two stereo outputs, selectable from buttons ...
doug's user avatar
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3 votes
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117 views

Gain of single input differential amplifier

When performing the small signal analysis of the circuit shown below, with \$ V_{1} = V_{in} \$ and \$ V_{2} = 0 \$, and output taken from \$ V_{02}\$, I consider the small signal model for half of ...
bebop's user avatar
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Calculating the gain of a specific transistor amplifier circuit

NOTE: There is an error in the drawing above — C1 should be connected to the emitter, not the collector. Hi Electronics SE, hope this is the right place to ask this, if not I'll gladly take it ...
Nicolas Zaugg's user avatar
3 votes
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750 views

Connect speaker directly to Samsung Galaxy S6. Minimum impedance accepted

I want to connect an external (passive) speaker (3W/16 ohm) directly to my Samsung Galaxy S6 using the headphone jack. I want to do this on my bicycle using the smallest space possible. Connecting the ...
IceCold's user avatar
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3 votes
1 answer
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Connect a vibration motor to a headphone jack

I would like to solve the following problem: I have a a variometer-device for an RC plane. Its receiver has a standard 3.5 mm headphone jack that provides a beeping sounds to my headphones. I would ...
Christian H's user avatar
3 votes
2 answers
1k views

RF amplifier not working

I designed an RF amplifier that should amplify signals in the FM band of 88 to 108MHz. The circuit is as shown below: The input to the circuit is connected to an USRP through an SMA cable. The output ...
Kevin Selva Prasanna's user avatar
2 votes
0 answers
130 views

Simulation of transimpedance amplifier in LTspice

I am trying to simulate a circuit that is presented in a research paper by Dr Behzad Razavi. I am using LTspice for the simulation (please see the attached image and netlist for the circuit). I am ...
Masood Salik's user avatar
2 votes
0 answers
96 views

OpAmp Selection | Sine Wave Amplifier: 30 MHz, 30Vpp with 15V offset

I am currently working on amplifying the output sine wave of the TG5011 professional signal generator. Below are the specifications for the amplifier I am aiming to create: Power Supply: A single ...
Vitaliy Petliakivskyi's user avatar
2 votes
1 answer
85 views

Class AB amplifier sizing

I have simulated a class AB amplifier as shown in the attached diagram. Its working pretty fine at 5kHz and 500mV input signal. However, the simulation fails when I try to change the requirements to ...
Farai Mahachi's user avatar
2 votes
0 answers
42 views

How to minimize voltage-current phase shift in the output signal of a circuit?

So, I have this circuit (Fig. 1, LTSpice ASC file here: https://github.com/PauloCarvalhoRJ/Circuits/blob/main/driver_speaker_5W_RMS.asc) designed for small scale geology investigations (using sound ...
Paulo Carvalho's user avatar
2 votes
0 answers
73 views

Super tweeter: voice coil wire gauge x power rating apparent inconsistency?

I'm an amateur electronics experimenter/enthusiast. I have an 8-ohm super tweeter from JBL (sold in Brazil as model ST200) whose RMS power with passive crossover is 100W @ 8kHz. It's quite a large ...
Paulo Carvalho's user avatar
2 votes
0 answers
28 views

Is it necessary to implement a sensing resistor plus pre-amp with Faraday cage on a PCB if I would like to have the range about 10nA measurement?

I put a 60 kΩ sensing resistor plus low-bias current amplifier with a gain of 500 into an aluminium bag and tied it to AGND for EMI shielding. The second stage is an ADS1256 24-bit ADC. The purpose is ...
Bill Lin's user avatar
2 votes
1 answer
343 views

BJT amplifier design

I am trying to design a BJT amplifier with the given parameters and limitations. The circuit is shown below. Parameters: Vcc = 15 V RL = 20 kΩ beta = 180 Vbe(on)= 0.6 V Cµ = Cπ = 0 Limitations are: ...
Aldocest's user avatar
2 votes
0 answers
65 views

Can anyone help me find this IC SZ9KH?

I tried looking for datasheet for SZ9KH but can't find anything. I encountered this IC on a board that needed to be amplified. Mostly i want to know how does the amplification works? Is it an op-amp ...
Ali Tavoosi's user avatar
2 votes
0 answers
276 views

Sziklai pair style amplifier design

I am a beginner. I have built this schematic in LTspice. It's a five transistor amplifier with 2 voltage gain stages, 1 input stage, 1 output stage and 1 pair of Sziklai pair transistors. On testing ...
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2 votes
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92 views

LM386 driving transformer going into oscillation

I have a transformer on the output of a LM386. The circuit works just fine with 42TU003-RC, but when I use any other transformer the circuit goes into osillation at ~350 kHz on the output of the LM386....
Electric Circuits And Such's user avatar
2 votes
0 answers
105 views

Function generator impedance matching with an amplifier

I am currently designing an experiment with a material which at low temperatures (below 180K) works like a light detector for infrared. There needs to be a bias applied to the sample which has to be ...
DFYD's user avatar
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2 votes
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122 views

DDS reconstruction filter after amplifier?

I need a clean sine wave from 10 kHz to 2 MHz as an excitation source for an eddy current probe. The sine wave will be generated by an AD9833 DDS with a clock frequency of 25 MHz. As a reconstruction ...
TonyDublov's user avatar
2 votes
0 answers
281 views

Design of transistor amplifier for nanosecond signal (with NPN transistors)

For a project/learning experience I want to design/build an amplifier. The signal I’m provided has an approximately 1ns pulse width (duty cycle of 1%) with a peak of 2.2V and a repetition frequencyof ...
ulix's user avatar
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232 views

Designing the first stage (common emitter) of an amplifier that will drive an 8 ohm speaker

I have to design an amplifier (can be one stage or multiple thought I am thinking multiple) that will drive an 8-ohm speaker and have a gain of at least 10 V/V (about 20 dB) given Vcc = 9 V. It also ...
Nicola's Tesla's user avatar
2 votes
0 answers
269 views

100Hz noise at hi-fi amplifier tone control after servicing power supply

I have an old Revox B780 HIFI amplifier / radio tuner. It was working perfectly fine except that it could not longer automatically search for radio stations and lost its memory of stored stations ...
ARF's user avatar
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2 votes
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Calculation of power dissipation of a MOSFET circuit

As a part of an assignment to design a common source amplifier, I came up with this circuit: simulate this circuit – Schematic created using CircuitLab The transistor is a 180nm technology with ...
KaBe2003's user avatar
2 votes
0 answers
78 views

Voltage-divider bias common emitter calculations are yielding unexpected results

I performed an analysis on this voltage-divider-feedback common emitter. My result in simulation is relatively close, but doesn't quite check out. Where did I go wrong? I'm new to this and ...
nuggethead's user avatar
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2 votes
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173 views

How do I perform ac analysis of common emitter with voltage divider feedback?

I'm working towards understanding voltage-shunt feedback. I'm about halfway there, and stuck. I am building a simple common emitter with voltage divider feedback. I managed to get it biased to put ...
nuggethead's user avatar
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2 votes
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How do you find rO when solving this differential amplifier?

gm could be determined using Jacoletto (40*Ic, where Ic was found while solving the bias point)? Some of my attempts at solving the circuit
Ioan Andrei's user avatar
2 votes
3 answers
3k views

Measuring RMS power output from audio amplifier channel

I am looking for a simple way for getting the RMS power output of an amplifier channel set to some arbitrary gain. I want this in order to find the maximum level I can safely set the amplifier at for ...
user2418372's user avatar
2 votes
0 answers
53 views

Adding Line Out / Sub Out to LG soundbar

I have LG Soundbar with wireless sub. I am trying to add Line output, so i could connect a wired sub. I took some pictures of the boards and chips. If someone could point me in right direction on ...
user3365751's user avatar
2 votes
0 answers
80 views

Portable Headphone Amp Power Supply 18V MCP73871 TPS61178 TPS7A470

Disclaimer: I'm fairly new to diyaudio, amplifiers, power supplies, schematics, PCB design and everything that this forum touches on (read: noob), so I urge you to be patient with me - I am eager to ...
Mladen G's user avatar
2 votes
1 answer
97 views

Generating +65 V (positive) and -65 V (negative) voltages from two 12 V batteries using cheap step-up converters?

I need to power a 300 W class D amplifier with positive and negative 65 V. As I'm a do-it-yourself guy, I didn't know about positive and negative voltage and ordered a bunch of these normal step-up ...
HimG's user avatar
  • 21
2 votes
0 answers
83 views

Step response of Power amplifier

i have the parameters for this linear amplifier Swell rate >52 V/µs Bandwidth DC … 5 kHz Power 3 × 30 kVA rise time at nominal voltage (230 Vrms) is 5 µs. and the transfer function is: $$F(s)=e^{-0....
Mostafa mk's user avatar
2 votes
1 answer
136 views

Power amplifier - unexpected Bode plot

I designed this schematic for a power amplifier project at university. The problem with it is the Bode plot, because as you can see on the Y-axis, it doesn't even reach 0 dB and frequencies reach up ...
Mixera4's user avatar
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2 votes
0 answers
197 views

Does UJT work as amplifier?

I had got a question in job interview " Draw a circuit of common emitter amplifier using Non Bipolar Transistor." As the question said Non Bipolar, so I assumed that it might be related to UJT. But ...
Jack Danniels's user avatar
2 votes
2 answers
2k views

How to estimate the voltage gain, Input impedance, current gain, power gain, and output impedance for the amplifier in the fig?

β of the BJT is 100 and from dc analysis it is found that the quiescent point is ICQ=4.12mA and VCE = 6.72V. If the emitter resistor RE is subdivided into RE1=100 Ω and RE2=900 Ω, with bypass ...
Prajakta Bhutkar's user avatar
2 votes
0 answers
316 views

Uniden BC780XLT Radio scanner, unknown modification

I recently purchased an old Uniden BC780XLT scanner. It has been modified replacing two smd resistor with THT resistors with different values. I am curious about this modification: what does it do? I ...
Wolfdale's user avatar
2 votes
1 answer
120 views

Determining gain, KCL/KWL (Basics)

Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load. So the gain would be: \$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms ...
math101's user avatar
  • 31
2 votes
0 answers
2k views

Simple MM Phono Preamp Design

I'v found myself in need of a new preamp for my turntable (the one built into my power-amp went out with a bang and tripped the breaker!). I'm using a moving magnet type cartridge with output around ...
G Frank's user avatar
  • 167
2 votes
0 answers
307 views

Max Input Voltage for a BJT amplifier

I have built a BJT amplifier and I have a function generator connected to the input of my circuit. I have also connected both channels of an oscilloscope to the input and output of my circuit. I need ...
Edmund Blackadder's user avatar
2 votes
0 answers
602 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 ,...
user196563's user avatar
2 votes
1 answer
428 views

Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
Allison_81's user avatar
2 votes
0 answers
157 views

Trying to figure out what kind of input signal this loudspeaker amp circuit needs

I'm still trying to figure out how this door intercom module works. It's a 18y old siedle TLM 611-0 module, I figured out the mic part, there the audio signal is modulated onto the current the mic amp ...
evilscientress's user avatar
2 votes
0 answers
362 views

Problem simulating LMP8645 current sense amplfiier in LTspice

Basically the problem i am getting is that the output offset voltage is extremely large (58mv) here is the datasheet for the amp: http://www.ti.com/lit/ds/symlink/lmp8645hv.pdf on page 9 it shows ...
user192's user avatar
  • 21
2 votes
0 answers
98 views

Transfer function of loop-back bias circuit for RF amplifier

I am trying to implement a current mirror as part of a bias circuit for a RF amplifier. I want to do a transfer function of the bias circuit since it creates a loop from the amplifier fet drain to ...
EE_Guy's user avatar
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