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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Describing an audio processing circuit fault
How could I describe an audio processing circuit fault to a circuit designer where the following symptoms occur:
After a period of silence in the recording, the first segment of audio is missing/...
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AV receiver does not output Bass frequencies - how do I fix this [closed]
I have a Pioneer AV receiver which recently went bad. I can hear only the high frequencies from the speakers.
It does not matter which input source I select (tuner, dvd, cd etc.) and it happens on all ...
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Flame ionization detector 2 µA [closed]
I want to detect a flame using Flame ionization. But I don't know how to convert the 2 µA of current to a usable signal (24 V or more, digital). I have searched around the internet but all I could ...
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Input Noise Of An Op-amp
I want to detect a 200 nVrms signal at 30 kHz. For this purpose, I will build a circuit whose block diagram is shown below. First, I will take this signal and amplify it by 40 dB using a preamplifier (...
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Transistor selection in a 500mW Amp schematic
Why are these specific NPN and PNP transistors selected. Why not use 9014's and 9012's ??
Also, I see the power supply is 12 VDC. How do you calculate the output to the 8 ohm speaker? Would you have ...
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Review my 5-37Hz filter and amplifer. Will it work? Am I missing any other simulation. (Made in LTspice)
Context. I am using this filter and amplifier to detect Schumann resonances. These are EM modes of very low frequency (7,14,20,28,33) of pT range. My goal is to use a copper coil sensor. These are AC ...
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Non-inverting DC Summing amplifier - single supply operation
I need a single-supply non-inverting summing amplifier for DC signals. Because I do not have a negative supply available, the obvious solution of using standard op-amps as inverting amplifiers seems ...
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Purpose and selection of inductor for RF power amplifier that has a VCC pin (MAX2616)
I am currently building an RF amplifier PCB for around ~2.4 GHz using the MAX2616, which is a broadband RF amplifier for 40 MHz to 4000 MHz.
Looking at the datasheet, I am confused about the purpose ...
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How to measure audio frequency distortion without expensive equipment?
I'm building some BJT amplifiers, and I'm currently getting distortion values via Multisim simulations. However, I'm not fully sure about the results I've been getting, and I would like to double ...
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Can I use OPA2227 to Make Low Pass Filter and Amplifier with Gain of 50~100
I am looking for low noise opamps and the one that caught my eye was OPA2227 and is available locally. Its a dual opamp and was wondering to use it for the as low pass filter with cutoff of 38 Hz and ...
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Current Mirror In Differential Pair Amplifier
I am designing a differential pair that is connected to a current mirror. I have calculated the drain resistors of the differential pair to draw around 16.5 mA and achieve a gain of 20 dB. When I ...
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Trying to limit the current going through a transformer coupled to a Piezo Speaker. Why is the speaker louder using an Saturated NPN transistor?
I'm working on a project where I need to update an existing design to resolve an issue with the audio amplifier circuit overheating when the volume is set to HIGH. My approach was to replace the NPN ...
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How is the 4.5V delivered in this charge amplifier circuit?
So I have found this circuit from this website:
https://sound-au.com/project202.htm
As you can see in the picture there is the 9V battery powering the omp amps, but for the +4.5V, how is that ...
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Why is amplifier bandwidth defined at −3 dB?
Why is the voltage amplification factor of an amplifier or a filter generally expressed by its gain in decibels, and why is the bandwidth of this amplifier defined at −3 dB?
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Pull-pull and push-push amplifiers
I know about push-pull amplifier stage, but recently I came to know additional configurations like push-push and pull-pull stages, from a question I was solving.
But couldn't find any sources about ...
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Simplest Way to Pre-Charge Capacitors in a High-Impedance Amplifier
My project includes a PIR sensor. The sensor should start reliably detecting motion within 8 seconds after power-up. The amplifiers in PIR circuits have high gain thus large resistors, causing a long ...
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Understanding an unusual combination of crossover diodes in a class AB amplifier
Another user had a question about distortion in an audio amplifier. The culprit seemed to be oscillations around Q2-Q4. Here it is again for reference:
Not having a lot of experience with class AB ...
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Thermocouple analog amplifier
I designed a circuit to amplify a thermocouple voltage. It is intended to have hot junction hotter than cold junction. ie, voltage is positive.
Edit: The system is powered by a 2S lithium battery. ...
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Converting transducer echo signal to logic 3.3V signal
Hello — recently I have been working on an ultrasonic transducer project. The transducer simply works by transmitting pulses while the receiver waits for the echo. When there is water flow in a pipe, ...
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JFET amplifier clipping on positive peaks after increasing VCC from 9 V to 24 V — lost headroom on top of sine wave
I’m having trouble with a small JFET amplifier stage after raising the supply voltage from 9 VDC to 24 VDC.
The circuit originally worked fine at 9 V, producing a clean sine wave. With 24 V, the top ...
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Can I drive a Helmholtz coil with an audio amplifier?
For my personal project, I want to drive a Helmholtz coil of 8 ohms with 100Hz signal.
My current setup looks like this:
Function Generator (FY3200S series DDS Function Signal Generator)
Audio ...
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Why is a DC bias voltage (V_BB) needed in a BJT amplifier, and how does the coupling capacitor make this possible?
Source: "Electronic Devices", Floyd, 10th Edition, Fig. 4-21, p. 180
I’m learning about transistor amplifiers and I want to make sure I properly understand the role of the bias voltage and ...
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2-amp fuse burned; how high can and should be the amp rating?
At the beginning of the positive line of a step-down converter with “AZ34063UP” IC (input: 12-24VDC; output: 5VDC, 750mA. There are 3 electrolytic capacitors in this circuit, 2 33uF on the input side, ...
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Eliminating 60Hz pickup
I have built a small PCB of the following circuit. The PCB has a ground plane under the top layer. The amplifiers are MAX44260 with the rails at 3.3V and 0V. The input pulse is 3.3V so the peak of ...
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Folded cascode large signal properties
I've been reading Ravazi's book Design Of Analog CMOS Integrated Circuits.
regarding the end of chapter 3 (Single-Stage Amplifiers), the book presents the folded cascode (Page 90)
regarding this ...
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Hum noise from electro magnetic amplifier (inductor)
I have build this circuit which is taken from here: link
I'm having an hum sound regardless if the device is pointing a electrical device or not. What can cause this issue?
Here is a sample of the hum ...
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Do I need some sort of buffer?
I'm using a CA3080 op amp in a transimpedance configuration to convert the current flowing through a phototube into a voltage that I can display on an oscilloscope.
With the output fed straight into ...
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Bluetooth speaker to wired: Easy way to bypass BT to link AUX directly to amplifier
Trying to turn a Bluetooth speaker unit into a wired one. Need help in knowing what needs to be done to make the speaker take AUX line-in audio to output it without any BT interface in between. It is ...
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LM386 input stage protection
I'm using the LM386 chip to amplify audio and I designed a circuit diagram for this purpose.
Short request: I want to reach the goal of protecting its input avoiding signal distortion/degradation.
A ...
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Feedback on my VHF small signal amplifier
What I am looking for is RF design feedback on the following small signal amplifier for VHF.
Background: I have been designing a small signal RF antenna amplifier (receive) for the 2 m ham radio band (...
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Switching between gain settings in a non-inverting amplifier
I have a few questions about the circuit below. It comes from the LabTool oscilloscope add-on board for the LPC Link2. It's purpose is to attenuate the input signal with a voltage divider, and then ...
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AB Amplifier driving a transformer looking like a short?
I am attempting to design an analog sine generator that should create a low voltage 60Hz sinusoid, amplify the voltage to around +/- 15V and then use that signal to drive the primary of a step up ...
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AC-DC using NDR as startup
I have been reading about the Wikipedia article on negative resistance and in particular, I'm interested in this circuit (also linked at Wikipedia):
I was wondering if we could convert this into DC ...
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Why the 5kHz low-pass filter is not working in my simulations in LTSpice?
The circuit I'm trying to simulate is shown in Figure 1 below.
SOURCE: Tools for physiology labs: an inexpensive high-performance amplifier and electrode for extracellular recording.
Land BR, ...
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Preparing the signal for a voltage squaring circuit
I am trying out a voltage squaring circuit from this paper¹, but there are a few things that are not clear to me.
The circuit in question is shown below. It is supposed to find the difference of two ...
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MOSFET Transconductance
I’ve come across three different formulas for calculating the transconductance (gm) of a MOSFET. While analyzing a cascode amplifier under DC conditions, each formula yields a different result. Could ...
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Load Cells - 4x full bridge or 4x half bridge?
After some insight to why 4 half-bridge load cells connected parallelly to one ADC is superior to 4 full-bridge load cells in the same way.
I have been informed that the difference in cost of both ...
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Explanation of a circuit (Filtering and Amplification)
Filering and Amplification Circuit
The purpose of the circuit is high pass filtering > amplification > low pass filtering
Signal with capacitor (C3)
This is the circuit with capacitor C3, but ...
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JFET Frequency Response Problem
Dear friends please help me to sorts this out.
I have attempted to design a simple CS type amplifier for 27 MHz based on 2N5486 JFET. Pretty soon I realized that the 15 pF of input capacitance of my ...
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Isolating LC filters in discrete amplifiers
Given a couple of two transistor amplifiers - CE voltage gain, EF current gain - with a multistage LC filter in the middle: how can the filter which is highly dependent on input and output impedance ...
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Darligton pair to amplify ±10mA to ±10A shows only postive swing; how do I get negative swing too?
I have made a Darlington pair circuit to amplify ±10mA to ±10A.
But it only amplifies positive inputs. How do I get it to work for negative inputs too?
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LTSpice op-amp non-inverting input acts like pull-up
I've been trying to analyze an op-amp non-inverting amplifier with LMH6629 with LTSpice using the PSPice file from official Texas Instruments site (
https://www.ti.com/product/LMH6629#design-tools-...
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what is the difference between FB pin and OUT pin in a FDA(Fully diff. Amplifier)?
I’m currently working on building a low-frequency thermometer, and as part of that, I’m studying a design described in a paper. My goal is to replicate the circuit and eventually improve upon it.
The ...
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Why are low frequencies being amplified more than high frequencies by the BJT in this amplifier?
I've been trying to make some simple amplifier circuits, but I realize now that there is a big piece of the puzzle that I'm missing. I have a simple bandpass filter feeding into the amplifier, but ...
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When playing sine into class D amplifier, why is Vdd ripple voltage the 2nd harmonic of the sine?
When driving a 1kHz sine wave into a class D amplifier, I measure the frequency of the voltage ripple at the Vdd pins to be primarily 2kHz, of course with other harmonics of 1kHz at lower powers. My ...
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BJT Amplifier design - assignment question
Here is my assignment question:
You are provided with a 230 V / 50 Hz ac supply, a 6-0-6 centre-tapped transformer and a BJT of dc current gain 150. Biasing the transistor using a supply of 5.6 V (...
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Amplifier from HCD-RG295
I disassembled HCD-RG295, its an audio system with CD, Decks, radio, and amplifier, and I want to take amplifier from it and make it work with aux, but I am not very much knowledgeable of what to do ...
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Biasing amplifiers in X-microwave Lego style PCB
I have bought a PCB of an amplifier, a table and two connectors.
The board is like a Lego. The problem with this is how do I bias it.
I have rf_in and rf_out but I don't know how to bias such things.
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Help with problem measuring power output of small RF amplifier. Different answer on oscilloscope vs TinySA
I built this single transistor RF amplifier about a year ago and it seems to work quite well but I wanted to try and characterize it more officially.
I was performing measurements on this amplifier ...
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