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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16 views

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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38 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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60 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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58 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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69 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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55 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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100 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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30 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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39 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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60 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
47 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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101 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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37 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
40 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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74 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
59 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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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
45 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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52 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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56 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
57 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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72 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
43 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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43 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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57 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
46 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
49 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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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
191 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
105 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
44 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 ...
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1answer
76 views

Capacitive load - Circuit protection

I have a circuit which drives capacitve loads (they vary from around 800pf to 1600pf) and because of circumanstances like air polution and dust it can come to electrical contact to the surroundings or ...
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4answers
107 views

Single Supply Class-A-Amplifier circuit to amplify voltage signal alternating around ground

I have a sensor which outputs a voltage signal alternating a few millivolts around zero volts and want to design a circuit which prepares this signal for processing by a microcontroller like in the ...
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63 views

Understanding RF amplification

as general interest I am trying to learn a little about RF, antennas and signal amplification, largely in the context of 2.4 GHz. I have read about two DIY projects that informed me somewhat: This ...
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1answer
60 views

Power consumption problem in high-voltage power audio amplifier

I have a problem with my power audio amplifier. I am unfortunately forced (because of the specifications I have been given) to make it work at a dual voltage of +-90V. Finding the components to do ...
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2answers
93 views

Need to map 0-5V DAC output to 0-10V output

I am using a TLV5618 to take a 16 bit SPI package to produce a voltage between 0-5V with 12 bits of resolution (4 control bits). Now I need to shift this signals from 0-5v to a 0-10v signal. I do ...
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71 views

Cascaded common emitter amplifier

Im trying to design a cascaded amplifier with 3 common emitter stages. As long as the input AC voltage is below about 20mV the amplification is fine, as you can see on AMP1. But the output of AMP2 is ...
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79 views

How to amplify without contact a 10-20Khz square signal?

I would like to amplify a square signal 50% PWM on a live wire, the wire carry also a sine wave 60Hz at 120VAC. The square signal will be only present a a few milliseconds after the zero cross. ...
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106 views

Interpreting results of a thermal camera - what should I expect to be hot?

I'm not a trained electrician, but I got my hands on a thermal camera to play with. Its existing documentation didn't help me quite understand what's going on when I see a hotspot. What components can ...
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33 views

TPA3220: Single supply operation - can I use AVDD to pull up RESET?

I've tried asking this question on the TI forums but have not been able to get a response, so I'm posting here in the hope that someone who knows the details of the TPA3220 will be able to answer! I ...
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95 views

Increasing output current of DAC

I have an application where my Arduino is controlling a mcp4725 DAC for a design replacing a sensor on an old car. The DAC provides the analog output voltage, .25V to 4.9V to the computer. I recently ...
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128 views

Why does an OpAmp with negative Feedback not amplify the potential difference on his inputs?

An OpAmp without any feedback just takes the potential difference between his 2 inputs and amplifies it by a certain factor. I know that in an OpAmp Circuit with negative feedback, we can make the ...
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1answer
114 views

Damaged solder pads on FX-Audio DAC-X6 Alternate solder locations?

I've tried to remove a faulty 6.5mm headphone jack from a FX-Audio DAC-X6 and ended up removing the solder pads from the board. I'm trying to save this instead of trashing it and buying a new one for $...
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2answers
2k views

Don't understand MOSFET as amplifier

When a MOSFET is working in its saturation region, it might be used as an amplifier. But, as far as I understand, the more you increase vGS (voltage between the ...
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1answer
25 views

LM4871 audio amplifier BTL configuration question

I am reading the datasheet of LM4871 audio amplifier. The typical application looks like: The datasheet says it is in BTL configuration. The 1st OPA inverts input signal and the 2nd OPA inverts again ...
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63 views

Amplifier Transfer Function Question

Hi, this is from Razavi's Analog CMOS IC Design book (2nd edition) - Pg 49. He says that " We observe that the circuit provides a gain of about 3 in the input range of 0.4V to 0.6V" But if you look ...
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45 views

“Linear” Amplifier

For example, the "small-signal" gain we find for a Common Emitter amplifier is -gmRc, (assuming no emitter degeneration) Rc being the resistance attached between the collector node and supply. Now, if ...
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4answers
51 views

Small Signal quantities

Behzad Razavi in his book mentions It is important to bear in mind that small signal analysis deals with only (small) changes in voltages and currents around their quiescent values.... If the ...