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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12 views
micro level voltage signals
I am currently doing a project in which I have to measure micro-level voltages (body potentials) and show the signal at the output of the amplifier.
I have used INA128 from TI as my first project with ...
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1answer
37 views
How to simulate the exponential growth op-amp?
According to Wikipedia, the following is the exponential output operational amplifier.
I would like to test this out in a simulated environment and see how this functions. For example give a sine ...
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0answers
45 views
Digital drop-in replacement for potentiometers
I'm looking to replace the potentiometers in a guitar valve amplifier with digital counterparts, to vary the controls with a microcontroller. Motorized potentiometers are not a solution due to the ...
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1answer
56 views
Newbie question: Feasible way of amplifying 100+ channels of slow and low amplitude signal
I want to amplify signal coming in hundreds of channels (sensor array each producing a very low amplitude 30-200Hz signal). For every channel i care only about intensity of the signal (i don't need ...
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2answers
73 views
What's wrong with my1943/5200 Mosfet Amplifier? Blown on first run
I have just brought an 1943/5200 mosfet based amplifier board. Shopkeeper said it's rated for 24-0-24 AC.
So I connected it with 24-0-24 transformer like this in image below.
As soon as I turned the ...
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3answers
103 views
Why is the maximum efficiency of a push-pull amplifier 78.5%?
One of the practice questions for my upcoming test is this:
After some googling, it seems like the correct answer is A. But why?
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1answer
25 views
Input Resistance and Mid-band Gain of a CE-CE Stage Cascade Amplifier
I am trying to calculate the Input Resistance and Mid-band Gain of a CE-CE stage.
Here's what I got so far:
I am having some doubts regarding my calculations though. Mainly with the input ...
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2answers
57 views
Why don't I get a signal on the load?
I don't get any signal on the load, what am I missing? Shouldn't it amplify the input signal?
I have 50mA from the current mirror, the Vbe on Q10 and Q11 is around 0.75v
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0answers
51 views
Designing a two stage transistor [on hold]
Ive been completely stump on this problem here, any help would be greatly appreciated!
Design a two-stage transistor amp with a differential input and a emitter follower output. The amp should have a ...
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1answer
61 views
Three stage amplifier
Well I need to design three stage amplifier
Im stuck on the output stage, I need that the AC Current on the load will between 20mA to 100mA, but Top current I get is almost 5mA, cant over pass it ...
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0answers
34 views
To use a LM392 do Operational Amplifier and Voltage Comparative [on hold]
The LM392 consists of two independent building-block circuits. One is a high-gain internally-frequency-compensated operational amplifier, and the other is a precision voltage comparator.
May I use ...
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0answers
29 views
Solving the MOSFET, using KVL?
The question is Find VD and ID? The FET has Vth = 1.0 V and k(w/l)= 1.0 mA/V2 and λ = 0, VDD = 5 V.
My question is can I use KVL like this
Vdd - R1 ID - R2 ID - R3 ID =0
rearranging for ID = 11/5? ...
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0answers
39 views
Cascaded Amplifiers & Constant Current Source [on hold]
this is regarding my Chegg homework help. So far no one has been answering me yet :( Can anyone help? I need to hand in these questions tomorrow
https://www.chegg.com/homework-help/questions-and-...
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2answers
67 views
Stk086 distance between pins? [on hold]
I have been trying to make a footprint for this IC, and trying to figure out the distance between pins, it is a 10 pin ic what do you think the distance will be?
What is the normal distance between ...
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0answers
41 views
Differential Amplifier Exam Problem
I am lost with how to approach part C and D of the question. In fact, I need some intuition with how to tune a differential amplifier.
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0answers
46 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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0answers
18 views
Small TPA3116D2 amp [closed]
So basically i got this 2x50W+100Wsub Tpa 3116d2 amp
Now my question is since the amp has an issue that it overheats the small orange inductors even when the sound system is idling(no signal) so it ...
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1answer
57 views
How to amplify current and buffer voltage
I have a battery supplying 5V@500mAh and an LED (the load) which draws 1000mA@5V (twice the current the battery supplies per hour).
I found some circuits that have NPN transistors only and other ...
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2answers
47 views
Amplifier advice for speech sythesizer circuit
I'm designing a circuit that hooks up an SP0256A speech synthesizer to an AVR microcontroller and would like some help with the audio output amplification.
The datasheet describes the output as being "...
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2answers
63 views
Audio amplifier for 600 ohm headphones
I am working on a design which must drive an audio output into 600 ohm headphones (aviation headsets). Normally, I would just use an off-the-shelf class D amplifier but I can only find ICs designed to ...
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1answer
44 views
MOSFET Differential Amplifier voltages via PSpice and by hand
I want to do an analysis on a differential pair and there is a problem when the pair is in common-mode, at least that's what PSpice says. I find that \$V_{DS}\$ of both MOSFETs is 1.1V and PSpice ...
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1answer
203 views
How do I appropriately power a headphone amplifier and where do I place the volume regulating potentiometers?
At the moment I am building a device that splits an analog stereo audio signal into
3 signals and amplifies 2 signals for headphones.
I need to know how to supply -12VDC and where to put the volume ...
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1answer
40 views
2-stage BJT CC-EC amplifier [closed]
Using proteus I designed this amplifier:
But I got this result:
I don't know what is the problem in my design. I've been changing the values of the linking capacitors but didn't get any result.
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1answer
45 views
BJT LT spice DC transfer characteristic
Why is it that the DC transfer characteristic isn't flattening out at -5 v, so it looks like a Z-shape? I did a DC sweep from -10 V to +10 V.
The input wave is a 2V sine wave for the graph below:
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1answer
59 views
Need help with three-stage transistor amplifier in LTSpice
I am currently attempting to design an amplifier in LTSpice for an E1 project. My professor tends to emphasize analysis of these circuits, so he hasn't really given us any kind of a design process to ...
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1answer
51 views
OP amp Comparator not working any tips?
I´m running out of ideas here.
I have a device that should always output a 5v signal, with a maximum tolerance of 100 mV (4.95 to 5.05 V).
I´m building a "tester" device. My tester will compare the ...
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0answers
64 views
Not getting smooth sine wave on the output of the power audio amplifier
Power audio amplifier circuit not giving me an smooth sine wave output.
Before iIadded the active bandpass filter I was getting smooth sine wave output with a current of 500 mA peak and 4V peak and ...
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0answers
57 views
Missing resistors vaules
A question for some guys is simple, but it is not for me.
I am having difficulties finding the right formula to calculate resistors value or voltage drop across
R1 through R8.
Does anyone have an ...
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1answer
32 views
Looking for a small comparators which do compare a input [closed]
and output when reach the set value。
Or can anyone tell a simple circuit to build one.
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2answers
73 views
Why my non-inverted amplifier does not work?
I'm trying to use a TL081, for which I used a DC power supply regulated by MPL1303, to feed the TL081 and a Vin from a DAQ assistant giving an analog signal of 0 to 5 V. I tested the signal from the ...
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1answer
70 views
Transistor current amplifier circuit
I'm trying to make a circuit that has a load resistance of 2 Ohms, load current draw of 2A and voltage of 5V.
The circuit can only be fed with a 5V@500mAh battery.
Here is a diagram I have thought ...
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1answer
27 views
Class a amplifier load capacitance
What would happen in a class a amplifier if I connect a capacitor in series with the load resistor (between power supply and the transistor collector)?
My goal was to block the dc qiescent current to ...
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1answer
111 views
Op-amp problem, two inverting amplifiers?
So I stumbled across a rather strange ideal op-amp circuit that I've never encountered before. I've done enough problems regarding inverting amplifiers, non-inverting, summing, difference, and such, ...
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2answers
64 views
Current sense amplifier
I came across this circuit for a high-side current sense using BJT current mirror, and I am trying to derive a formula for how I could calculate the sense voltage output (going to the FB pin) in terms ...
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2answers
80 views
Is my amplifier correct?
My goal was to amplify audio signal coming from Raspberry PI's audio jack, so it is louder. I have basically no clue what I am doing, but it seems to work - when I connect the speaker directly to the ...
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0answers
23 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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1answer
63 views
Class-AB Amplifier Excessive Heat
I'm using a TI TPA6017A2 as a pre-amp for an in-car audio application and it's getting excessively hot, to the point where the IC burns my finger when touched if I set the input volume to max. Beyond ...
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0answers
75 views
Extending the negative rail range for an Op Amp
I'm building a Transimpedance amplifier using the ADA4530-1 op amp by Analog Devices.
I'm attempting to sense a fA current signal that is always negative and I would like to see if it would be ...
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2answers
55 views
Amplifier MOSFET (25m - 5V)
I dont know how to amplify a signal of 25mV to 5V amplitud signal ((frequency of audio input cell phone)). I have this circuit so far:
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2answers
73 views
Not getting an ac current output through my speaker in my amplifier circuit
Will the dc current output affect the speaker, and prevent it from functioning properly? I have already tried different capacitors also change the input voltages and frequencies.
I would really ...
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1answer
124 views
when a diode is forwards biased can current flow backwards through it?
when a diode is forwards biased can current flow backwards through it?
this question comes from me trying to understand class AB amplifier biasing, so any additional comments about the diodes' use ...
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0answers
33 views
How do I design a MOSFET based amplifier with constraints
I am designing an amplifier using two MOSFET stages. The input is taken from a sensor and is to be amplified by a factor of 25. The output (of these two transistors) will be fed to a detector with a ...
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1answer
29 views
Matching Networks on Narrowband Multistage Low Noise Amplifier (LNA)
How does the inter-stage matching network of a narrowband LNA compare to that of a wideband LNA for the same multistage design? I've read somewhere that narrowband LNA does not necessarily require a ...
2
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1answer
67 views
Reasoning behind values of CE amplifier
I have the following circuit:
I am asked to choose values for the different components such that at the end, the amplifier meets certain requirements.
In the solutions, I am told that to minimise ...
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3answers
129 views
Is a bigger resistor different from a smaller resistor with same color stripes?
I changed a resistor with same color stripes Yellow, Purple, Gold, Gold on a Pioneer surround system but the only difference was that the I put was a bit bigger. The problem is the system went into ...
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1answer
36 views
Cascading an Op Amp at a desired frequency question
So I have a lab practical with the instructions
"Demonstrate an operational amplifier circuit which may consist of one or two op amps with a gain of X (±10%) and a -3dB frequency exceeding Y kHz. The ...
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0answers
22 views
Can I choose the 18W amp for my 1" tweeter (50 W AES Power Handling)
I have a question - I want to take a 18W TDA2030A amplifier kit to power my tweeter in my PA system. I have an active crossover in it, that's why I have separate amp for each driver. My tweeter is 1" ...
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0answers
60 views
LM386 and strange way of curbing noise
I am using an LM386 to drive a cheap 1-2 inch 8-ohm speaker.
The input to the LM386 is an output from a DAC, which is outputting a sine wave between 100-1kHz, so I don't need any frequencies above ~...
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0answers
17 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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1answer
68 views
How can I build BJT amplifier with Vin and Vout requirements (peak to peak values)
I have been working on a project but I'm not sure if I'm complying with the requirements that I was given.
Design a BJT amplifier such that VIN=0.1 V and VOUT=5 V (peak to peak values). ...
