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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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23 views

Cutoff frequency of class A common-emitter amplifier

I'm trying to understand the operation of a class A common-emitter amplifier, but I'm struggling to understand how the equivalent resistance for the cutoff frequency of C1 is determined. I also can't ...
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28 views

How to get the gain for this MOSFET amplifier?

This is a common drain MOSFET amplifier: simulate this circuit – Schematic created using CircuitLab This is its small signal model at low frequency: simulate this circuit I am at a loss as ...
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37 views

Need help with level shifting and amplifying a signal

I have a 1V pk to pk analogue signal and need to shift and amplify the voltage to 0.5-2V.The supply into the amplifier is ±10V. The frequency of the signal is 500 - 1000Hz. What sort of circuit ...
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Finding voltage gain and current gain using the load line in a common emmitor transistor amplifier

So this question is really annoying me for a while so I needed some help. I am given the output characteristics curve for a CE transistor amplifier. I also managed to draw the load line. They have ...
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32 views

How to obtain a high precision mV signal within a specific interval using a variable resistor?

I want to design a circuit which outputs a signal ranging from 0-70 mV using a variable resistor ranging from 80.51 Ohm - 183.05 Ohm and a supply voltage of 12 V. My idea so far has been to make a ...
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Sony Home Theatre Reciever producing high frequency constant volume noise while powered on

Equipment: Sony Digital Audio Control Center (Digital Cinema Sound) Model No: STR-KG700 Problem: High Pitch Buzzing coming from speaker output and headphone output (when plugged in). I have tried: ...
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71 views

Op - Amp: Linearity, Negative Feedback and Virtual Short

I need some explanations about Linearity, Negative Feedback and Virtual Short for an ideal Operational Amplifier. Precisely, I have been always told that an operational amplifier with negative ...
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1answer
72 views

Choosing Collector Current for Transistor Amplifer

I see in the guides to standard Bipolar Transistor circuits (emitter-follower, common emitter amplifier), they always say: Choose a quiescent current of 1mA. How is this value chosen? I look at the ...
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3answers
53 views

amplify/increase current from 9v battery

I have a working circuit that generates a signal (a range of slow and fast tones) and sends them to a speaker. I tried to switch to a piezo driver and speaker and was successful using the MAX9788 as ...
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1answer
55 views

Why noise when increasing amplification of last cascade of transistor amplifier?

I've made small amplifier for hand-made electric guitar - it is just two transistor cascades - and I've found one curious effect when increasing amplification. Some annoying noise (just typical ...
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1k views

Building an amplifier out of diodes

It is quite obvious that we can't build an amplifier out of resistors (because of their linearity). But is there a circuit theorem that states the impossibility of building an amplifier out of diodes (...
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67 views

Non-inverting amplifier with variable gain from 1 to 15

I need to design a non-inverting amplifier with gain from 1 (unity) to 15. From what I read, in theory this can be achieved by using a pot as the feedback resistor, but in practice this will only work ...
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42 views

Charging a battery bank [closed]

I am trying to build a battery bank charger with a 5 V solar cell. I am connecting the solar cell to the battery bank that says 5 V/1A input on it. I get 5 V out from the cell in the sun. But the ...
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2answers
49 views

Hand contacting op amp photodiode circuit causes interference - what ist the physic behind it?

I am new to analogue electronics and I am still learning about op-amps. I use the most common circuit for amplifying a photodiode's signal to measure it with an ADC: Amplification gain is 1M, the ...
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1answer
89 views

How can I get/build a current controller/amplifier?

Background: I have a Lorenz-actuator (coil+magnet) that I need to control precisely using a computer. The computer signal is output from a dSpace microLab box as an analog ±10V signal. This signal ...
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31 views

Question regarding Transresistance Amplifier Circuit

Something that makes me confused while reading a tutorial on the Transresistance amplifier circuit. Here is the picture of the circuit. It basically measures the current across the photo device and ...
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1answer
34 views

Microphone Pre Amp Book? [closed]

I'm wondering if there's a book that discusses resistors, capacitors, inductors, transistors, transformers, impedance, op amps, power supplies, and the general circuitry of a microphone pre amp. Thank ...
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Prevent click/pop from transient when bluetooth receiver disconnects?

I have a Logitech bluetooth receiver connected to my hifi to allow kids etc to play music from iPhones/ipads. However, it seems that the receiver itself has a sleep mode when no signal is being sent,...
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1answer
37 views

Speakers Power and Quality Difference Factor

I started tinkering with speakers (mostly amplifier circuits) and I learned a lot about how sound and amplifying works but I don't understand how to increase quality I have several kind of speakers , ...
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1answer
59 views

How to get stereo and mono signals simultaneously?

I have PAM8403 circuit module to drive my two 3W speakers. I want to drive a subwoofer with a different amplifier. I have a 3 inch subwoofer, and I'll get an amplifier for that. My question is how do ...
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1answer
57 views

Split Audio lineout into two different amps

I am using a 3116d with a lpf and a 7498 for the mid range. The audio signal comes from a common source. The cables are split and soldered, so that both amps receive the same input. However, doing so ...
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2answers
67 views

Amplify a sinking signal

I'm working with the DRV103 PWM driver chip; this chip generates an initial long pulse followed by PWM and is useful for driving coils/solenoids. The problem is, this chip operates at 8-32V, while the ...
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1answer
51 views

Active Mixer RF Input Power and Input IP3i, P1dB Question

I am new and learning in this field. The received signal is first amplified with SKY65404 LNA and secondly with HMC313 Amplifier. Lastly it is connected to Active Mixer ADL5801's RFIN pins. In ...
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1answer
99 views

LM386L does not amplify the microphone signal

I've encountered a problem. I recently bought a condenser microphone and I wanted to have some fun, so that if I said something into the microphone, I'd hear myself in the small 8 Ohm 0.5W speaker. I ...
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0answers
28 views

Amplifier for pulsed Radar motion sensor

I have a radar motion sensor, IPM-170. The output of the sensor is as follows: The AC motion signal is -+300uv and there is a DC bias around 150mv. I am applying the following circuit so I can run ...
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36 views

Thevenin Resistance in a op amp circuit

I created this circuit and I am struggling on trying to figure out the Thevenin resistance for this circuit.
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58 views

Audio amplifier output bypass capacitor

I'm currently designing a single rail power supply audio amplifier and just wondering what the benifits are (if any) and if its worth including a film/poly capacitor in parallel with the large ...
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1answer
32 views

pam8403 using low wattage speaker

I am using the output of usb sound card as an input to PAM8403 ic with specs from datasheet. However i am using 4 ohm 0.5 W speaker. So i have tried testing with that and it works but sometimes with ...
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2answers
97 views

Fixing an old radio [closed]

I am trying to fix an old radio that my girlfriend just bought. It's from around 1964. I'm just a normal electrician and I am not used to fixing things like this. Radio model: Huldra 7-45 Skapmodell ...
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1answer
34 views

Operational Amplifier and Strain Gauge

My laboratory involves using a strain gauge and an instrumentation amplifier to amplify the signal from the strain gauge. The op amp schematic is shown below: Any assistance with the following ...
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1answer
38 views

Thermocouple amplification configuration

I am relatively new to thermocouples. We are wanting to get the temperature of fire ball blast. We are using a Type-K thermocouple and a Phoenix Contact mini signal conditioner to amplify the signal. ...
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3answers
72 views

OP Amp 0-5 VDC Output

I have the circuit pictured below. I need to change the potentiometer from a 20K to a 5K and still get the 0-5 VDC output. VCC = 5V Is this possible? What needs to change to make this possible?...
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1answer
58 views

Electret micrphone amplification noise

I am building a circuit that amplifies an electret microphone with the use of an op amp. It does work, but I am getting a lot of noise at the output side of the op amp when I connect it to a pair of ...
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1answer
27 views

Successive Detection Logarithmic Amplifier

let's consider this logarithmic Amplifier: I do not understand why at the terminal LOG OUTPUT there is a current which is proportional to log(Vinput). The current flowing on each diode is equal ...
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1answer
43 views

Input impedance of High - Frequency Amplifiers

I have a question about the choice of the input impedance of a high frequency amplifier. In general I know from elementary analog electronics courses that it is good for an amplifier (for instance an ...
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1answer
50 views

Envelope Tracking Power Amplifiers

Do power amplifiers that use a dynamic power supply operate in the active region, i.e. as a voltage controlled current source? or do they operate in the saturation region? and how do the current and ...
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51 views

Using a double-gate MOSFET to design a class AB amplifier

I am currently tasked with building a class AB amplifier using double-gate MOSFETs. Since there isn't much literature available on the MOSFET itself (regarding biasing and actually using the device ...
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1answer
22 views

Input range for TPA311x

I'm reading through the datasheet of the TPA311x family. I'm looking for the input range for pins INPR and INPL but I cannot find this information. I see the absolute maximum ratings, but it's not ...
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1answer
42 views

TPA3118: coils and op-amp getting warm

I designed a simple board based upon the ds of the TPA3118. Here the actual schematic: When I power the device, even with no input signals, coils (L1..L4) and op-amps (IC1..IC2) reach a quite warm ...
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63 views

Calculate VI limiter in audio amplifiers

straight to the problem: I want to use VI limiter protection for the audio amplifier output. Here is a basic configuration: (Picked from: sound-au.com/vi.htm) As I understand it, using a resistor ...
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1answer
76 views

150V voltage follower

I am working on a datalogger to measure the voltage of a series of solar modules. I have 4 solar modules in series, let say 35V each. I am using an ADS1115 for the measurements. First I wanted to do ...
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1answer
42 views

Function Generator amplifier to drive resonance circuit help

I have a model resonance circuit that is excited with an auxiliary winding and I need to build an amplifier to be able to amplify the current from the function generator in order to drive the ...
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41 views

amplify the ac signal from fpga 3.3v to 5v with placing coupling capacitor at the input and output

In the above schematic I have reduced my negative voltage in the op amp , so that I get output voltage from 0 to 5v, otherwise I am getting the voltage from negative side. please suggest me the right ...
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1answer
53 views

Emitter follower for parallel LED switch

I’m trying to confirm that the solution posted in https://electronics.stackexchange.com/a/60868 will work for my application. I have four yellow LEDs with a 2v drop (yellow) and 30mA max current I’...
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1answer
45 views

Logarithmic Multi - Stage Amplifier

let's consider this logarithmic multi - stage amplifier: Each stage is an amplifier with this mechanism: if the input signal is small (under a certain threshold), it is amplified with high gain A; if ...
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1answer
47 views

Does input impedance of an isolation amplifier or a transformer have impact on common mode to differential mode conversion?

I have a question where I can only explain it clearly by an example. It is about conversion of common-mode interference to differential mode due to overall system imbalance. I will use below two ...
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0answers
32 views

Definition of operational transconductance amplifier (OTA)

I'm trying to understand the definition of operational transconductance amplifier (OTA). The book on which I'm studying defines it as a class of operational amplifiers which "achieves a high voltage ...
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3answers
181 views

Can I strobe a power led with an audio power amplifier?

I'm trying to make a fast LED strobe for visual periodic measurements of mechanisms, rotating objects to be specific. I "designed" an opto-coupler/MOSFET circuit and a transistor/MOSFET circuit. I ...
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3answers
91 views

Parallel RC as a filter?

I was looking at an amplifier schematic and saw a curious portion that I realized I wasn't sure what its purpose was. simulate this circuit – Schematic created using CircuitLab At first ...
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1answer
43 views

Increase range of an analog voltage output

I have a sensor that produces an analog voltage on output that can vary between 1,2 V and 1,4 V. As soon as my A/D converter on my Arduino would be not so effective with only 0,2V of variations, I ...