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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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46 views

Can I use BTL audio amplifier IC in single-ended output configuration?

I am designing a widget that has to have a speaker output (low power, between 1W and 2W, 8 Ohms, low-quality) with the limitation that one end of the speaker must be grounded. There are lots of audio ...
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2answers
100 views

Double Balanced Mixer

Consider this double balanced mixer: Its output contains only the frequencies generated by the product of those of LO and RF signals, where LO is supposed to be a large signal (which switches ON and ...
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1answer
52 views

Finding the sinusoidal input voltage of an amplifier

An amplifier has a linear transfer characteristic passing through the origin (0, 0) and with output voltage saturation at L+ = 10 V and L– = –8 V. The amplifier gain is 100 V/V. What is the ...
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1answer
39 views

TDA1904: Output volume is not amplified

I have created this circuit on the breadboard. Circuit Page no.4 of this TDA1904 datasheet: Supplied voltage 10V from pin2 and supplied signal from 3.55 mm jack to pin8. I have connected the wires ...
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2answers
199 views

Class A Audio Amp - Improving Efficiency With A Mosfet CCS

I'm designing a class A audio amplifier but am struggling with the efficiency of my circuit. I know of 'push-pull' Class A designs, but only want to use a single output mosfet. I would like to hit a ...
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1answer
41 views

Amplifier Voltage

I'm studying for my electronics exam and for this particular problem I have: Av = –85 (V/V), Ap 21 (dB) power gain, Ap = 3.41 (W/W), L+ = +9 (V), L- = -6 (V). Now the next exercise asks that: ...
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2answers
48 views

2VCC in a BJT C.E. amplifier

It is known that it is possible to get 2Vcc output voltage in a BJT Common Emitter amplifier by using an RF Choke (instead of a simple resistor) connected to the collector. Precisely, we will get at ...
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2answers
72 views

differential amplifier gain

i know that the differential gain of the differential amplifier ( mosfet or bjt ) is _gmRc or _gm Rd looking at the curve : if the current went down in one side and up in one side the gm will change ...
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1answer
38 views

How can i get the Q operating point of the differential amplifier?

I'm working with this type of configuration: Differential amplifier, and I need to find the current for this circuit so I can have maximum symetrical swing, and for that, I need to find the operating ...
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2answers
62 views

Stability and Positive/Negative feedback

I often read that positive feedback is used to get oscillators (since the output of the circuit is summed up to its input signal and so leads to instability), while negative feedback to get amplifiers ...
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1answer
117 views

Removing noise from TDA2007A Audio amplifier circuit

I have built an audio amplifier circuit like the test circuit in this TDA2007A datasheet I am going to use this circuit with Raspberry Pi 3B+ and going to feed sound via 3.5mm of Raspberry Pi to this ...
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1answer
118 views

How to calculate error amplifier output in amplifiers

I'm trying to derive an accurate formula for the output of an error amplifier in the class D amplifier I'm simulating. Most literature on the error amplifier/integrator in class D amplifiers glosses ...
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80 views

Designing a two stage differential amplifier with MOSFETS

As a part of a "Test you understanding quiz" i had yesterday at school were we tested our understanding of differential amplifiers and mosfets i came across a question that asked us to design a ...
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1answer
130 views

Class A amplifier with preamp design

I am currently working on a class A audio amplifier designed to work with line in voltage (about -400mv to +400mv). I plan on using an IRFP240 for the mosfet but am undecided on the transistor stage. ...
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3answers
140 views

why is transformer not considered as an amplifier?

I know that in a transformer the power is conserved on both sides, and hence there's no power amplification as such. That's fine! But if I instead want only a voltage amplification, then choosing ...
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54 views

IC for audio amplification of 3W and 4Ohms 2 speakers with Raspberry Pi

I was using a PAM8403 amplifier with Raspberry Pi to run 3W 4Ohms 2 speakers but the sound is low. So I am thinking of building an amplifier circuit. Sound low means when I connected this to mobile ...
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0answers
102 views

What will be small signal trans resistance gain of shown circuit?

Take beta = 99. I analysed this circuit using first considering this circuit as feedback circuit with shunt-shunt type of feedback and then did the same analysis considering that the circuit is a ...
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1answer
36 views

Direct coupling Biasing of Two stage amp

General question. I see a lot of two stage amplifiers with a diff pair input and a cs second stage. In IC design these two stages are always directly coupled ie. the dc bias of the second stage is fed ...
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0answers
42 views

Passive PA resistor came loose

I need some help! I have an Australian Audio XRS12 speaker. After a gig I heard something rattling around inside the cabinet. I opened it up to find an 8 ohm resistor that had come loose. It looks ...
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1answer
69 views

input resistance of differential amplifier

i have a question about the differential amplifier i know that the input resistance for the common mode is Rin = rpi + 2 Beta Ree / 2 but my question is what is the input resistance for the ...
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1answer
72 views

Laser audio transmitter - need substitutes

I'm building a laser audio transmitter that uses amplitude modulation to transmit audio via a 5mW laser beam. The transmitter uses a microphone, an operational amplifier (to modulate the signal if I'...
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2answers
110 views

Question about differential amplifier

why is there 0.7V instead of 1.2V on the common emitter? if you go through Q1 mesh : Ve = 0.5+Vbe = 1.2 instead of Ve = 0+Vbe = 0.7 from Q2.
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1answer
66 views

Designing 2-stage BJT CE class-A voltage pre-amplifier with specified goals and without global NFB

BJT CE Class-A Voltage Pre-Amplifier Suppose a design requirement limits the selection choices to the following class-A BJT common emitter stage topologies. No global NFB is permitted. Only local NFB ...
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1answer
106 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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3answers
73 views

Class A amplifier - Transistor Q-Point calculation

Reference: http://www.learningaboutelectronics.com/Articles/How-to-find-the-q-point-of-a-transistor-circuit I am trying to understand this q-point calculation. I recently asked a question about the ...
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4answers
516 views

Class A Amplifier Design: Emitter Resistance Voltage Drop

I am trying to understand the design principles of Class A amplifiers, primarily for audio purposes. I have read several times that "the voltage drop across the emitter resistor should be in the ...
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2answers
44 views

Load Cell Amplifier

I'm not from an electrical background and looking for possible options to amplify the load cell output. I'm using the following loadcell with a 2 mV/V output. http://www.sentranllc.com/pub/...
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51 views

ESP32 with LNA and PA

I would like to add a low noise amplifier and a power amplifier to the ESP32. As you may know there is only one RF output on the chip. I was thinking of adding an RF switch, and switching between ...
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1answer
64 views

A passive differential to single-ended load match

I'd like some suggestions for some passive differential to single-ended speaker audio level matching circuits for a particular situation where an external power source for an amplifier is not ...
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2answers
2k views

Rail-to-rail op-amp only reaches 90% of VCC, works sometimes, not everytime

I have created a simple data acquisition module for measuring 5V signals. There are 18 analog inputs on this board, all of which are a copy of the schematic below. Each input has an op-amp (MCP604) ...
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2answers
630 views

Why is the output signal of my amplifier heavily distorted?

I checked the circuit 1 million times. I got it from a website. Everything is correctly connected. The sound is loud, but it is very distorted. I use a 9 V battery. Where is the problem? :( ...
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0answers
75 views

TDA7294 blew up [closed]

I have created this schematic connection of TDA7294 on and had a PCB solution. Connected to power supply +-25VDC. But at first start the TDA7294 blew up without any load on output pin. I started check ...
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1answer
71 views

Why polarize a differential pair with a diode-connected BJT?

I was having a look at the LM148-family design At the input stage, why would you polarize a differential pair with a diode-connected BJT? If I'm not mistaken, the output resistance is also going to ...
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2answers
116 views

Operational Amplifier Problem

I'm trying to find $$\frac{V2}{V1}$$ as a function of x. I found this circuit but noone gave good explanation. I think I understand the way this potentiometer works, but I just can't work out the ...
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0answers
67 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 ...
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0answers
47 views

Difficulties simulating transimpedance amplifier

I am developing a transimpedance amplifier as an assignment for a faculty course and I am running into problems when trying to simulate my circuit in ADS Keysight, even though I am quite sure how my ...
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1answer
47 views

Transmitter / Amplifier matching

I am trying to add an amplifier to a transceiver to increase the range but I am not sure how to add the reference schematics together (eg what components to remove, combine, etc). The top schematic ...
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2answers
56 views

Help understanding current noise

My understanding of current noise is that you multiply the current noise by the input impedance and that gives you the noise level in volts. I’m looking at the LMC6001 opamp and it states in the ...
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2answers
428 views

What does the wifi amplifier exactly amplify?

The question is not exactly about the wifi, but on how does this operate in full duplex, in principle? As an practical example, lets take some commercial amplifier. As we can see from the picture, it ...
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2answers
88 views

How to derive formula for emitter current flowing through Re?

Ie = Ve/Re I was thinking about using that approach but i have been doubting myself if that is the right approach to go with, because then i have to express the emitter current in term of alpha and ...
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1answer
59 views

Headphone amplifier: negative charge pump vs. phantom ground

I want to use a "capacitor-less" headphone amplifier that doesn't require DC blocking capacitors at the output. I found a headphone amplifier that has a negative charge pump that generates an ...
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1answer
77 views

Cascode Amplifier Biasing Sequence

I'm trying to understand the proper biasing procedure of a cascode distributed amplifier part that requires three power supplies. A positive drain-source VDD, a negative gate-source VGG1, and a second,...
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1answer
41 views

Calculate values of resistors in a given BJT amplifier circuit [closed]

I have the circuit shown below and i have limited resistors to make it work. The LED's rated current is 10mA so Ic = 10mA. I know that beta for the transistor is 100. The resistors are (I have 2 of ...
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1answer
37 views

What exactly is source reflection coefficient and input reflection coefficient?

I just come across learning Microwave Amplifier. And I encounter two similiar coefficients: source reflection coefficient and input reflection coefficient. Illustration below from Microwave Engineer, ...
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1answer
139 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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1answer
122 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
59 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
63 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
164 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
51 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 ...