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)

6
votes
5answers
2k views

Circuit to “zoom in” on mV fluctuations of a DC signal?

I have a signal that is roughly 0.2V + noise fluctuations of order 0.1-2 mV. Ideally I want to amplify this signal such that the mV fluctuations become about 1V. In other words I want to amplify the ...
2
votes
1answer
89 views

Output Filter Components Breaking Class D Amplifier Chip

Hi I am designing a class D amplifier PCB using the TPA3122D2 amplifier chip. I am planning to base my circuit on the schematic from the evaluation board: I bought components of the same values given ...
0
votes
1answer
149 views

How do I calculate expected output voltage of car audio amplifier with given conditions?

I have a 4-Channel Amplifier rated at 800 Watt RMS per channel @ 2 Ohm load. Channel 3 and 4 are preset to operate a subwoofer speaker while Ch 1 and 2 are set to operate mid-range speakers at ...
0
votes
2answers
50 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 ...
0
votes
2answers
69 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 ...
0
votes
0answers
55 views

Replacing AC transformer

I've encountered a problem while replacing the AC transformer of a soundsystem composed by 3 loudspeakers (1 bass loudspeaker (4Ω5W) and a couple of highs(can't open to see the specs of these)) and a ...
0
votes
2answers
130 views

Purpose of attenuation before op-amp input

What is the purpose of putting attenuation circuit before op-amp input? I cant find the actual reason for this topology. Is there any reason behind it? Why we need to attenuate the incoming signal but ...
-2
votes
3answers
111 views

Is it possible to wire car speakers straight to a 3.55 mm jack? [closed]

Is it possible to re-wire car speakers (model JBL GT7-5) to a headphone jack (3,55 mm stereo plug) directly without an amp? And if not, what do I need to-do? This what I know about the speakers: ...
0
votes
0answers
27 views

RaspberryPi: Load cells and HX711 amplifier

I've created an app that will read 10 weighing scales at the same time with separate values but since some wires are like 1 meter long, I get so much noises in the values. I just wanna know if what's ...
23
votes
6answers
4k views

What's the point in a preamp?

I'm talking in the context of guitar amps, but I assume that this question is relevant for any type of audio amplifier. Very often in amplifier schematics I see two stages of amplification -- first, ...
0
votes
1answer
65 views

Isolate two audio inputs to amplifier circuits on ground connection

I am using an arduino to monitor the voltage of the input lines to a stereo amplifier connected to speakers. When the arduino detects voltage changes on Chan1 or Chan2 it activates an IR LED to change ...
5
votes
2answers
1k views

Can a zener diode with a higher power dissipation be used in place of the original one in an audio amplifier?

Following my Marantz PM-68 repair question, I would like to change a faulty zener diode used in the amplification stage. I don't really understand the purpose of this diode but I guess it's used for ...
1
vote
2answers
67 views

Op amp diode clipping

I am creating the following diode clipping circuit: The input signal, Vin, offset is removed and the signal is amplified using an op-amp. Then there are two diodes designed to clip the signal to +/- ...
0
votes
0answers
36 views

how to power up a subtractor using a window comparator?

I'm making a circuit that will detect whether a voltage(V1)is in between the range 1-2 V. If so I want to switch ON a subtractor and output V1 - 1 V. I initially thought of connecting the output of ...
3
votes
2answers
358 views

Why does the small signal analysis work? (Intuition)

Consider the Large and small signal model of the MOSFET amplifier, simulate this circuit – Schematic created using CircuitLab How is this transformation valid, I get the linearization of the ...
8
votes
2answers
1k views

Circuitry of TV splitters

I'm trying to understand the circuitry of TV signal splitters and associated boosters/amplifiers, and I have two questions. My situation is as follows. I have a TV aerial (antenna) in my loft. It ...
2
votes
1answer
1k views

Mains transformer blew up amplifier, incorrect description in wiring instructions?

I am assembling a power amplifier from a kit I purchased from Velleman (Module: VM100). With the amplifier I purchased this mains toroidal transformer - . The amplifier came with these instructions: ...
1
vote
2answers
164 views

High pass filter for use in amplifier circuit

I've designed an amplifier for a small ac signal (amplitude of around 5mV, frequency 252kHz) with a BJT (2N2222.) The BJT is set up in a common emitter amplifier configuration, with the biasing ...
1
vote
1answer
88 views

Adding multiple transistors to increase the output power of an amplifier

I have a Sony amplifier 500 watts I like to increase the out put power to 1000 watts if I add more transistors will it work. How practical is this can this be done. Thank you
17
votes
2answers
282 views

How to find the problem of this old Marantz amplifier?

After a first question referring to resistor symbols, I'm back with this old Marantz PM-68 class AB amplifier and I will refer to components using their ID that can be found in the service manual. ...
-1
votes
1answer
62 views

Subwoofer amplifier IC repair? [closed]

I bought a subwoofer as is. The sub worked, but the speaker terminals didn't. I took a look inside and the amplifier IC(TDA 7265) looks like it shattered somehow. Any ideas what could have ...
2
votes
2answers
63 views

LM386 speaker distorts

I've built an amplifier with an lm386 but when I connect a speaker (8ohm) to the output I get a very distorted signal. The problem appears only when the speaker is connected. If I connect an external ...
0
votes
1answer
44 views

Can an amplifier slew rate be used as a low pass anti-aliasing filter?

A slew rate calculator says that for an arbitrary 100MHz signal a minimum slew rate of 1884V/μS is required. If I used an amplifier with that exact slew rate is it also a low pass filter? It seems ...
5
votes
3answers
1k views

OP Amp not amplifying audio signal

Hi, part of my project requires me to amplify an audio signal coming from an electret condenser microphone which outputs an average of 10mVpp to approximately 2.5Vpp. I Used two cascaded non-inverting ...
0
votes
2answers
116 views

Removing noise induced by IC (Ground loop?)

I want to build a simple, portable, MP3 decoder + amplifier. I use a PAM8610 amplifier and a generic MP3/bluetooth decoder. When I power each of them from separate batteries (7.4V) it works nicely. ...
0
votes
3answers
94 views

Which is more efficient: A much larger than needed step-down voltage converter, or one rated closer to the actual load?

I'm designing a custom audio system for my electric motorized pedicab. The motor of my cab runs on a 48 V 33 Ah battery, and I have planned to use a 48 V to 12 V step-down converter to simultaneously ...
1
vote
2answers
187 views

Amplifier Design Project

I need help with starting on the design of amplifier design project, given the following listed below specifications. To be more precise, having learned about the different BJT amplifiers, such as ...
0
votes
0answers
82 views

Amplifier voltage gain

How to determine the voltage gain and input/output impedance of the following circuit given that R1=273.56 and R2=2325? I have been trying to calculate the voltage gain through solving small signal ac ...
1
vote
2answers
134 views

Understanding the basic common emitter amplifier

I'm struggling to understand intuitively this basic circuit: simulate this circuit – Schematic created using CircuitLab I know that out is \$k\cdot\mathrm{in}\$. What I'm struggling with is to ...
-1
votes
2answers
69 views

Step by step approach to the analysis of transistor circuits

Below we have a circuit cosisting of three transistors. Is there any systematic approach to the analysis of such circuits. We are asked to find the values of R1 and R2 and aslo the operating point of ...
1
vote
1answer
34 views

Rheostat with Hydraulic Amplifier Card

simulate this circuit – Schematic created using CircuitLab I am designing a control system for a Hydraulic Valve Amplifier Card (Bosch VT-VSPA2-1) and I need to send an analog input signal to ...
2
votes
2answers
206 views

Pre-amplifier input protection

I am building the Velleman K1803 pre-amplifier kit. This amplifier has a maximum input signal of 40mv. The audio input to the pre-amplifier will be a piezo-electric sensor, and this can certainly ...
1
vote
1answer
478 views

Compact circuit with multiple PAM8403

I'm building a 6 channel circuit with the PAM8403 (Filterless 3W Class-D Stereo audio amplifier) and was wondering if I could make things more compact by using less components. Is it possible to ...
1
vote
1answer
68 views

CD4011 Oscillator Square Wave Output Fed to Transistor Audio Amplifier; Volume Control Question

I built an audio frequency square wave oscillator using 3 gates on a CD4011 quad NAND gate IC. I then fed the output of the oscillator (pin 11) to a very basic "push-pull" transistor amplifier on the ...
3
votes
1answer
136 views

Reverse engineering old record player schematic

So this is a loaded question I know, but I'm stuck and I don't know where to go from here... My mom has a super old record player. It's build into a bright orange suitcase which is pretty cool. We ...
1
vote
2answers
59 views

Circuit Choices for AmpIifier Input

i have breadboarded a TDA2050 amplifier, using this schematic i get good sound intensity with a half acceptable quality. the down side is the constant noise and humming. i have found a possible ...
0
votes
2answers
102 views

How to mount four 6-wire 10V load cells on Arduino or Raspberry Pi?

I want to connect four 6-wire load cells (Tedea Huntleigh Compression & Tension Load Cell 300kg, 15V dc, IP67, product page and datasheet) into an Arduino or Raspberry Pi and get four independent ...
4
votes
2answers
2k views

I found an audio circuit and I built it just fine, but I find it a bit too quiet. How do I amplify the output so that it is a bit louder?

I want to try something audio related and found the following circuit from technoblogy I built it and loaded a sound clip. Everything works fine, but I found it a bit too quiet and I want to amplify ...
0
votes
0answers
53 views

Distortion via Powered Speakers and not in Headphones - 1 Transistor Amplifier

I'm trying to make this NPN amplifier circuit work for my battery powered computer speakers. This circuit works fine if i connect headphones to it in output, but has distortion when connected to a ...
0
votes
1answer
44 views

Why does the output voltage of my linear gain amplifier depend on the JFET gate voltage?

I am trying to build a linear gain voltage controlled amplifier using an N-channel JFET as a voltage variable resistor (see circuit below). As the circuit is set op now, I would expect Vout to be ...
1
vote
1answer
47 views

HFA3096 transistor array breakdown voltage

In the book Learning the Art of Electronics, one of the labs is to build a differential amplifier with a CA3096 transistor array. The author admits that the chip may be difficult to find and gives the ...
0
votes
4answers
80 views

Op Amp: signal measurement that is below its common mode input range

I was wondering, how is possible to use an op amp, which its common mode input voltage is (V-) + 0.2V to (V+) - 0.2V to measure signals as low as 10mV for example? I'm looking for an ...
2
votes
1answer
57 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% ...
0
votes
1answer
94 views

Class D Amp headphones grounding circuit

I am having a problem with some of the class d amps I've played with (PAM8302A), and it seems like this article here describes my problem: https://www.edn.com/design/analog/4313726/Add-headphones-to-...
0
votes
1answer
79 views

MONO output from STEREO amp (T-Class)

I have ONE Boston Acoustics Micro90X Speaker (for 15-125 watt amps), and a Topping VX1 2x25W Class T Amplifier (notionally 2 x 25 watts) that I don't currently use. I thought both of these gave ...
0
votes
0answers
27 views

Unbalance effect in differential amplifier

Consider we have the below differential amplifier : Consider that the two resistors R2 are not balanced and the unbalance in this resistors is represented by delta R2. The common mode rejection ...
0
votes
0answers
20 views

Calculate Capacitor mf for PAM8402 Amp Powered From RPi

Trying to figure out what capacitor mf I should use for a 5v PAM8402 audio amp that is powered by a Raspberry Pi. When the amp is first turned on it triggers the Pi's low voltage warning. I'm using a ...
0
votes
0answers
39 views

LM4890 amplifier and CR1616, how to improve power consumption?

I'm a hobbyst trying to design a simple circuit for amplifying the PWM audio output of an ATTINY85. I'm using an LM4890 (1W amp) and a 1W microspeaker. The problem comes when I supply 3V with a small ...
2
votes
1answer
57 views

Variable gain amplifier output appears on circuit positive and negative supplies

I am trying to use the analog devices AD600 in a simple sonar system. However, the performance of the chip is severely degraded because whenever the chip's output is nonzero, a portion of that output ...
0
votes
0answers
40 views

Three level PWM modulator circuit feedback simulation

I'm trying to design a three level PWM circuit with feedback and i'm struggling to understand the feedback aspect. The design is based on this design by Texas instruments and modified to suit three ...