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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Low power tube headphone amplifier design

I have never worked or even listened to tubes/valves before, so its about time I did. I wanted a simple design to work with being my first tube project, and have found this from diyaudioprojects.com: ...
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1answer
66 views

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 ...
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0answers
55 views

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 ...
3
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1answer
45 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 ...
3
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2answers
52 views

Ferrite rod antenna for DCF77 simulator

Where I live, in central Italy, the signal of DCF77 (the German longwave time signal and standard-frequency radio station, which operates at a frequency of 77.5 kHz) is so weak when it arrives, that ...
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67 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 ...
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1answer
66 views

Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get \$10^6-10^7\$ photons, which get converted into electrons with about 80% ...
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255 views

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 ...
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1answer
275 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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0answers
672 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 ...
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29 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 ...
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0answers
35 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 ...
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1answer
72 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 ...
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0answers
48 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....
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51 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 ...
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60 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 ...
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1answer
70 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 ...
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349 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 ...
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82 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 ...
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76 views

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 ...
2
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1answer
523 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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3answers
153 views

Behaviour of Voltage on Base in a fixed BIAS Common Emitter Amplifier

I'm having some trouble understanding the behaviour of the basic common emitter fixed bias amplifier. I've been looking at this for awhile now and I'm starting to think there is a foundational ...
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189 views

Identifying Noise in 12AU7 Based Headphone Amplifier

I've been working on making a tube based headphone amplifier as a fun personal project. The amplifier is based around this 12AU7 vacuum tube. The project for the most part is following this existing ...
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260 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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188 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
156 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 ...
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133 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 ...
2
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1answer
166 views

Is the Gummel-Poon model useful for explaining AC transistor amplification?

Let me be clear: By amplification I am talking about the process of boosting the strength of an AC signal. Thus, where the output power to input power ratio is greater than 1. Now suppose we have a ...
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74 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 ...
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2answers
470 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 ...
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1answer
204 views

fixing the amplifier in an old arcade machine

I just joined and need help. I'm trying to fix the amplifier in my Chicago coin speedway arcade machine. It basically works but it has a bad hum in it. I did replace a couple capacitors that were ...
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0answers
78 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 ...
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190 views

Asking about old russian amplifier internal circuit

I worked with an old russian machine in my lab, which contains an input from a photodiode with amplification circuit. The amplification is composed into 2 stages , the first with a JFET transistor ...
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2k views

Why do some audio amplifiers connect the power ground to the signal ground?

Trying to add a MIDI synthesizer & speakers to a keyboard here. Here's the schematic: simulate this circuit – Schematic created using CircuitLab But I was getting annoying crackling and ...
2
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1answer
191 views

Non-linear amplification circuit

I've got a few questions about a task from my exam preparation paper. The sketch below shows the circuit in question. It is given that U_E varies between 0V...3V. The operating voltage U_B is 10V. The ...
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2answers
141 views

Amplifier output goes haywire with load attached

I'm trying to create an op amp using FETs and BJTs. I need the gain to be over 500, currently without a load attached I have the gain about 1000. The input is a 0.05V sine wave, the output is ...
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4k views

MOSFET Parameters LTSpice

This is the LTSpice model of the Fairchild 2N7002 NMOS transistor. ...
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2answers
388 views

Discrete Distributed Amplifier

I read about distributed amplifiers. I know they are used in MMICs, but I wonder whether it would be possible to build a distributed amplifier with discrete components. In my opinion, it would have ...
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1answer
443 views

ac voltage regulator

I'm trying to built a circuit that amplifies music from a phone to a headset, based om ambient noise level. So if you're surrounded by noise, your music volume will turn up and in silent surroundings ...
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0answers
1k views

HTC 10 DAC/amp specifications

I'm going to be doing a final year project revolving around music production and DACs are pretty important. Not going to go into detail (unless this question requires it) what the project is but I ...
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0answers
1k views

Low pass filter for differential signals

I'm building an adc and amplifier circuit for sensing a differential signal out of a pressure sensor. My plan is to use a circuit very similar to what is seen below: The total differential output ...
2
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1answer
154 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
2k views

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 ...
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4answers
193 views

Can anyone identify the components circled in black? Weber 6049A Schematic

I have a 1936 era Weber amplifier (6049A.) Can anyone help me identify the 2 components I have circled in black? Red/Purple and Orange/Black (one of the other components also has a green circle on ...
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30 views

What determines the upper limit of the capacitive load on a DAC?

I need to drive a number of piezoelectric actuators. The AD5535B seems promising because of the high number of channels and low cost (and I happen to be able to borrow one for testing) but sadly, the ...
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1answer
33 views

Simulation of distortion from output inductor in class D amplifier, e.g. inductor non-linearities modelling

I'm new around here :) So, I am doing a university project regarding the effects of the output filter of a self-oscillating class D amplifier for low frequency audio signals, e.g. subwoofers. The ...
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1answer
115 views

About the heat of the matching circuit of MRF151A

I output 100W(@100MHz) under the following conditions, but I do not know the reason why the temperature of the device becomes high and the solution. Source matching: Function generator → Cp(82pF) → Ls(...
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1answer
69 views

Single supply amplifier biasing

I'm trying to understand this circuit. I can see that BW1 is a low pass filter and BW3 removes any DC from the output signal, but what does BW2 do? If it is acting as a filter, is it a high pass ...
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0answers
46 views

Issue with Video Splitter

I'm trying to integrate a video splitter for CVBS signal into my circuit. The Video amplifier I'm using is ADA4853 from Analog Device. In the datasheet, there's a sample circuit for video splitter ...
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52 views

How is this amplifier stable at 1GHz

The task is to design a amplifier for maximum gain, which means conjugate matching. The S-parameters at different frequencies are as follows Now for 1GHz $$K<1 \text{ and } \left|\Delta\right|<...

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