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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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307 views

LM386 guitar practice amp circuit not working, need help finding mistake

Im very new to electronics and I built this guitar amp circuit on a breadboard: and it was working really nicely. Now Ive decided to put the circuit on a universal pcb which i'll use in the actual ...
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54 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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88 views

Why resistor is used at the output of OPAMP?

I'm reading this note and in Figure 1(page 1), there are two resistors R5 and R10 whose use I don't understand. From my understanding, R5 would cause offset due the input bias current and R10 would ...
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94 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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60 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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106 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 ...
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47 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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68 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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141 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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881 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 ...
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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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90 views

How to make a guitar amp switcher?

So I'm trying to build a guitar amp switcher (and I don't really know what I'm doing =)). The idea is that guitar out is connected to X4 jack and then switched to either X1, X2 or X3 jack, which ...
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53 views

Amplification problem

I am using an instrumentation amplifier AD620ANalong with another amplifier TL084CN in series. Both have gains of 100 which essential for me since the input is in microvolt range. The frequency is 87 ...
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53 views

Simple push-pull problem

I've made a circuit based on the schematics below, which works fine at simulation. The goal is to add some extra oomph on the output of a LT1210 opa (V1) to drive a piezo element at higher voltages ...
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28 views

Gain bandwidth product of amplifier in a DC scenario

I think I have a simple (but still to me confusing) question regarding the gain bandwidth product (GBP) of an instrumentation amplifier: Datasheet (AD8237) I have sensors that change their output ...
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44 views

Issue with powering MP3 module with Amplifier

I'm not a electronics engineer/student, so please escuse me if my query sounds a bit naieve. I have a Mp3+FM module (link) which I can power with a regular micro USB charger(or desktop USB). As the ...
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55 views

Portable Guitar Amp - Distortion, Volume & GND

I have tried following the given schematic There are 3 things I am unsure of (what I tried): The Volume 5k Potentiometer: I have tried adding a volume control to the schematic by placing the ...
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26 views

Operation of Swing-Type Voltage Controlled Amplifier

I'm trying to understand this Swing-Type Voltage Controlled Amplifier which is found in the classic Roland TR-808 drum machine. What I understand currently is that the input signal to the base of the ...
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34 views

Common Source with Active Load

I'm trying to design this circuit using gm/Id method. I am already able to achieve the desired GBWP and Gain (this is just a simple example so I'm just trying to achieve both) but I'm having trouble ...
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71 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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52 views

Maximum mid-band gain of s.s. model MOSFET amplifier?

Schematics I need to find the maximum possible gain for this NMOS cascode circuit. Here is the s.s. model: Work I used nodal-matrix analysis (basis is KCL) to find the gain (\$A_v\$): $$ \...
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67 views

Crackling sounds when both speakers are connected?

I have finished my amplifier using the LA4597 chip following the schematic below. So far everything's working fine. However, I noticed something. Some songs crackle the speakers (probably because of ...
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100 views

Differential amplifier circuit - output voltage

I have a homework problem. We have a differential amplifier circuit with two supply sources: \$V_{CC}=-V_{EE}=5V\$, that has two identical NPN transistors and three identical resistors. T2's base ...
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75 views

What fan could I use to extract hot air from an oven?

I am making an reflow oven. I've decided to use the picoReflow to do the job and monitor it. The oven is originally a lab oven, and it doesn't cool quickly at all. It has a vent at the top which I'd ...
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101 views

Is ripple voltage is too high?

I'm trying to calculate voltage ripples on bulk capacitors of my guitar amp. Here's a schematic of it: simulate this circuit – Schematic created using CircuitLab According to formula Vpp=I/fC, ...
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49 views

Filter question, shelf or pass?

In the circuit below: I often see capacitors like C4 added in the feedback path of a non-inverting audio amplifier, and often times I heard that it acts like a high-pass filter. However... At ...
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37 views

How can I bias this Differential amp. circuit at the best operating point?

I'm looking to find a way to bias this circuit: I've written down a couple of equations for DC load line(and also DC half circuit): and these two as AC Load line: Rc is given by 1K and you can see ...
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45 views

Need fast and exact voltage follower or divider cascade

Intro: I'm designing a makeshift oscilloscope and now need an input cascade for it (it is more fun project for me, rather than industrial-grade tool). The matter is I want to get something faster ...
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44 views

Headphone Amp Impedance Select Switch

I'm designing a headphone amplifier, and I'd like it to be compatible with both 32 ohm and 600 ohm headphones. Therefore, I figured I could introduce a switch which allows the user to change the gain ...
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53 views

Precision battery voltage meter, Auto adjustment by R-2R

For a more precise measurement of a battery voltage I'd like to apply auto adjustment. The input voltage ranges from 2.5V-4.2V (single cell) to 20V-72V (module). At the moment the input voltage is ...
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59 views

HCS301 Remote External Antenna

I would like to amplify the range of my remote control which is built on HCS301 chip (it's a KeeLoq remote). I'm not sure where should I solder the external antenna to be the most effective. Also, I'm ...
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0answers
154 views

Audio op amps - what do they do to the audio I hear from the speaker?

I have a simple DC circuit which outputs audio from a ESP8266 attached via 2 wires and a NPN transistor to a simple speaker. It uses this library : https://github.com/earlephilhower/ESP8266Audio/ to ...
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87 views

what is normalized transconductance uesd for?

The transconductance is defined e.g. for BJT by gm = dIc/dVBE with VCE=const (1) where Ic is the collector current and VBE is base-emitter voltage, and from (...
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132 views

OpAmp Clipping? Issues

I am trying to amplify a simple 120mVPP sine wave (4K Hz) to a 5VPP signal being made by an AD9850 being controlled by a raspberry pi. We started off using a 741 but realized after asking you guys ...
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442 views

Photodiode OP-AMP circuit for UV light radiation

The project: The aim is to be able to use the photodiode to detect plasma (radiation in the UV light spectrum). The photodiode suggested for this application is the BPX65 and I currently have access ...
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40 views

What sets the MAG of a BJT?

Suppose you design ideal matching networks on the input and output of your transistor so ALL we're concerned with is the transistor and the packaging. What semiconductor physics or parasitics or ...
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70 views

Influence of NFB on the Gain of Amplifier

NFB is an acronym for negative feedback. Lets say that we have an amplifier with three stages: input (differential) stage followed by voltage amplification stage and output power stage. And we have a ...
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70 views

High pitched feedback or interference in system with amplifier and Raspberry Pi

I have a system running on 12V currently provided by a current-limiting power supply. In parallel this source feeds an amplifier and a 12V to 5V transformer. The 5V transformer directly feeds a ...
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593 views

Solid State Output Tube Driver for a SE guitar amp

I'm learning as I go once again. Consider this output stage segment from a guitar amplifier I physically built: The LND150 is an "depletion mode" MOSFET, whereas the IRF820 is a normal "enhacement ...
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573 views

Connect speaker directly to Galaxy S5. Minimum impedance accepted

I want to connect an external (passive) speaker (3W/16 ohm) directly to my Samsung Galaxy S6 using the headphone jack. Is the impedance too small? What is the minimum impedance that I can use? Is 16 ...
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109 views

Analogue multiplexer using JFET for small signals

I'm working on a circuit with a non-inverting amp and I would like to switch between two reference voltages, both with low output impedance. So in effect i want something like this: simulate this ...
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0answers
2k views

MOSFET Parameters LTSpice

This is the LTSpice model of the Fairchild 2N7002 NMOS transistor. ...
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0answers
470 views

XR2206 Signal generator amplifier

Probably a silly question but I'm still a total noob on electronics. I got my hands on an old non-functional XR2206 based function generator and I wanted to bring it back to life and in the meantime ...
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0answers
196 views

Photodiode JFET amplifier stage in pinch off?

In the circuit below, it seems that the JFET is biased in a regime with very low current (pinched off?). With respect to most designs I came across, this one uses rather large source and drain ...
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0answers
241 views

Li-ion BMS/PCM Use Cases

I am building a portable bluetooth speaker. I am using 4 18650 Li-Ion batteries and using 4S 14.8v BMS/PCM charge/discharge protection board with balancing. This board works great, but the challenge ...
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2k views

Speaker protection using only zener diodes?

It is crucial to match amplifiers to speakers correctly and use them with care. But in some cases you want extra protection from blowing up the speaker. I have thought of a ridiculously simple idea -...
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570 views

Replacing ceramic capacitors with film in PSU

Some Behringer Truth B2031 came back from a friend and they're acting up. first thing I noticed was the four .1uf ceramics that are in parrellel with the bridge rectifier diodes have experienced ...
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117 views

Common mode choke to boost cmrr of transformer input

I was wondering, can a common mode choke be used to enhance the CMRR of a transformer coupled amplifier Even further? What are the drawbacks?
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88 views

2x rs232 communication, single wirelss connection, also rs232 to control load cell perameters

I am struggling to find any information on the ability to have 2 rs232 connections with 1 wifi connection. I have found this wireless chip, which supports, five Ethernet ports, two serial ports: http:...
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773 views

two opamp instrumentation amplifier

I was looking for some instrumentation amplifier, and I've been catched by this one: The part number is LT1002. In the caption it's written: Gain = R4/R3 * [1 + 1/2*(R2/R1 + R3/R4) + (R2+R3)/R5]. ...