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)
3,852
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Resistors in a transistor circuit
I am not an electrical engineer but I was just reading a book about electronics. I am just a bit confused about how to analyze this amplifier circuit.
In this case, why are R1 and R2 in parallel?
I ...
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2answers
122 views
How to measure very low current by amplifying it?
I am trying to measure current from a DC circuit. So it basically I am trying to make an ammeter. I am using ACS712 20A current sensor and Arduino UNO. Theoretically, I can measure a minimum of 50 mA ...
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0answers
43 views
why does it make the composite amplifier circuit stable
I reversed engineered a headphone amplifier based on composite topology with opa1612 and tpa6120a2.
there's two capacitor and one resistor (circled in red) that I don't quite understand. I know this ...
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1answer
112 views
Why does volume above 80% break my speaker (PAM8403, 3w 4ohm, 18650)?
I am new to working with electronics and I am building a simple speaker.
The Problem
The speaker I built so far (poor sound quality aside) stops working if the volume is above ~80%. By stop working I ...
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1answer
39 views
How to linearly boost the output of a Gaussian shaping amplifier?
I have a pulse detection set up that takes in analog pulses (with relatively long tails, gamma spectroscopy). This pulse is sent into a shaping amplifier, that removes the tail, and shapes the pulse ...
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2answers
32 views
Am I measuring the Op-amp MCP6004 IC output voltage correctly using Arduino
Right now I am testing an MCP6004 Op-amp IC. A sensor in my main circuit going to give me a signal in the range 0-0.5 V max. So, I want to amplify this in the 0-5V range so that my Arduino reads it ...
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1answer
65 views
How can I increase the base-emitter voltage of an NPN transistor in forward active region?
For a project which involves amplification, I think I have to increase the base voltage, keeping the emitter voltage the same so that my circuit will not go out of forward active region as the ...
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4answers
101 views
Can I power a 100w amplifier with a 33w PSU?
I purchased a small 2 channel amplifier for a DIY audio project (Amazon link). I'm hoping I can connect it to a power supply I already have to drive a pair of small speakers.
PSU: 19V 1.75A DC (33w?)
...
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37 views
Is the output resistance of the first amplifier the input resistance of the second amplifier?
If I cascade a MOSFET based amplifier with another one to form a multistage amplifier, then in small signal analysis, will the output resistance of first amplifier become the output resistance of ...
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1answer
223 views
How to design a good common-collector amplifier?
I tried to simulate an example common collector amplifier given in the book Electronic Devices by Floyd.
The circuit depicted in the book is:
I used LTspice with transient analysis to implement and ...
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0answers
51 views
Designing a hybrid RF ampilifier with tube and transistors
I have an 807 vacuum tube and I want to design a RF power amplifier with it.
Since I have only one tube so I want to use transistors for the rest of the power amplifier circuit.
The 807 tube will be ...
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0answers
40 views
How do I increase the voltage gain of a Common Emitter + Common Collector without distortion in Vo?
I started with R1 and R2 half of what they were now, and with R_C = 5k. This had a gain of about 11, I managed to increase that by increasing R_C, but it seems to be plateauing when I start to get ...
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19 views
Is there a typical “Active Directivity” for LDMOS components?
Active Directivity is a measure of how much an amplifier's source match potentially affects its output impedance, or its load match affects its input impedance. High active directivity is a good thing....
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1answer
22 views
When using a Primera-Line Wattage and Current Meter, is it showing AC or DC measurements?
I am new to the electrical engineering stuff and am looking for some guidance.
I'm going to be designing a off-grid power system for some devices. So I will need to get the power measurements from ...
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1answer
28 views
Connect antenna to FM circuit
I designed a Colpitts oscillator with a single transistor amplifier stage. I now have to connect the antenna to the circuit through a coaxial cable. Do I have to redesign the output impedance of the ...
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1answer
22 views
RFC plus Rc in Colpitts Oscillator
I understand that the Radio Frequency Choke at the collector of a Common emitter is suppose to block the radio frequency from reaching the transistor and therefore interacting with the output. So by ...
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1answer
39 views
What's the maximum possible power output of this RF CATV amp?
please tell me what is the maximum possible output wattage that this RF CATV distribution amp (see below for specifications) would likely output with maximum possible input before damage? ~13 mW is ...
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56 views
Boosting an analog voltage signal
I have a 0-3.3V analog DC signal and want to change that into a 0-5V analog DC signal? How should I go about doing this? An op-amp? DC boost converter? If it is an op-amp, what does the circuit ...
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1answer
80 views
Make: Electronics Experiment 11 - Is this what the loudspeaker should sound like?
I'm working through Experiment 11 of Make: Electronics (1st edition since I bought a component kit that matches that edition).
I have the circuit configured below, but I'm not sure that the ...
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1answer
46 views
colpitts oscillator does not work with small inductance
Hi I am trying to build a colpitts oscillator with frequency of 10K Hertz. This circuit works fine with L2, C3 and C4 as they are in the picture. However, there is no way I achieve 10mH of inductance ...
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1answer
36 views
Class AB Amp Distortion / Repair
I'm trying to troubleshoot a (bass) guitar amp of mine. The output should be clean, but it distorts at VERY low levels. I pulled out the pre-amp board and determined firstly that the distortion is ...
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2answers
51 views
Is running 4 18650 batteries in parallel too much current for a small RC circuit with the same voltage?
I built this small RC deadbolt lock and everything works great, however, I need to fix the issue of battery life before it is finished. Originally the circuit had a 3.7V, 800 mAh battery. I would like ...
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Clarification on amplifiers [closed]
Can I use 2 LM311 in place of 1 LM385mm?
LM385MM is a dual operational amplifier and LM311 is a differential amplifier so according to me we can use, it is just that LM385mm is low power device so it ...
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1answer
51 views
Square wave voltage regulator
I wanted to build a simple amplifier for a square wave generator with the following configuration:
The presence of the amplifier is crucial since with my 12Ω load the output peak current may be near ...
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1answer
37 views
Voltage gain, input/output impedance using multisim.. How? [closed]
This is the picture of my amplifier circuit using multisim... But I'm not very familiar with this software and thus... how do I do the AC analysis to get the voltage gain, input/output impedance...?
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3answers
69 views
Op-Amp buffer Enable/Disable
I am designing an electric veichle controller for a University project. The motor driver receives an analog signal (0-12V) to adjust the speed. I use a digipot followed by a buffer to convert the ...
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2answers
45 views
Purpose of the C3 in this Transistor Arrangement
I'm working on building this circuit which is based on a "Fuzz" distortion guitar effect, and am wondering what the purpose of C3 is, connecting the two collectors of the transistors. Is it ...
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2answers
61 views
How to match harmonica impedance to a tube amp to eliminate feedback
What circuits eliminate feedback between hi z harmonica mics and high gain guitar tube amps?
Do FET circuits work? I have used tube bases attenuators in the past for 50 watt amps, but they reduce the ...
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1answer
61 views
Why is input resistance parallel with the base of BJT?
I'm solving for the third stage. The resistance looking into the base of Q7 is taken between its base terminal and ground as follows during small signal analysis for single end gain of Second Stage ...
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3answers
265 views
Where is my audio noise coming from?
I am using a Raspberry Pi 3B to output music to an audio amplifier board. Without the Pi connected, there is no noise from the amplifier. Once the Pi is connected (but not outputing any music yet), ...
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0answers
41 views
Design a cascode BJT amplifier to achieve a specified voltage Gain
I have been asked to design a cascoded BJT amplifier with the given specifications
Voltage Gain = \$76 \ to\ 84\ dB\$
Current Gain = \$66.5 \ to \ 73.5\ dB\$
Power Dissipation = \$ 3.5 \pm 5\% \ ...
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0answers
64 views
Designing a BJT cascode amplifier for decent gain and bandwidth
For my university course assignment I have to design a BJT amplifier using a Cascode stage with the following specifications using LTSpice. Only Vcc=3.3V and ground rails are available as well as a ...
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1answer
50 views
Voltage gain from the Amplifier input to the load
I don't understand where the solution for part C coming from. What I thought is also Vo/Vi. I found Vo as 303 mV and Vi as Vs*(10/10+100). However in solution it seems my thought is wrong. How should ...
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1answer
31 views
Switch Configuration for Variable Gain Photodiode Amplifier
In this article here:
https://www.analog.com/en/technical-articles/optimizing-precision-photodiode-sensor-circuit-design.html#
It states:
However, I don't understand the rather critical line "...
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34 views
What kind of two-pin connector is just a little smaller than jack 3.5?
I found an old DIY amplifier that I would like to use, but I ran into a problem: I don't know what kind of connector it has.
I know for sure that this device is an amplifier, since I once used it and ...
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2answers
62 views
Designing a common base amplifier to meet given specifications
I designed the circuit as below and I know that common base amplifier should have a unity current gain(usually <1) but I'm getting a very high gain. What might be the reason for this, is something ...
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1answer
55 views
How do i control a 6 V supply output based on a 5 V input?
I have a signal from a microcontroller that varies from 0 V to 5 V. I also have a separate 6 V supply to power a motor. I'm trying to design a circuit that allows the microcontroller signal to ...
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0answers
24 views
LTspice peak detector analysis: Time step too small
I made a peak detector with a test file in LTspice.
Here is the diagram:
When running the test file, I ran into this an error message:
Time step too small; time = 0.011, timestep = 1.26068e-017: ...
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1answer
77 views
Differential pair with current mirror - unequal currents
I designed a basic audio amp for learning purposes and now I'm trying to upgrade the differential stage with current mirror. However, I encountering a problem - the currents on both branches of the ...
0
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1answer
72 views
Design a Cascode amplifier using suitable topology to meet the specifications( by Varying W/L ratio) . VDD is 3.3V
CONDITIONS
Output swing has to be at-least 80% of VDD (> 2.64 in this case) .
Power supply rails available are VDD and ground only.
Only one current source can be used in the design IREF = 50μA.
...
6
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2answers
597 views
Amplify difference between two photodiodes
I have two adjacent photodiodes in photovoltaic mode, with two transimpedance amplifiers. Unfortunately, my MCU (nRF52840) is one meter away, and I expect a fair amount of noise to enter the system. ...
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4answers
99 views
Possibly unstable output of linear power supply due to very large current amplfication
I'm designing a linear power supply with an op-amp as error amp and a Sziklai pair as output stage as a hobby project (see schematic below).
I'm worried, that the output Vo will be unstable/...
17
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6answers
3k views
What is the purpose of the emitter resistor in a common emitter amplifier?
I'm struggling to understand the purpose of the resistor circled in red, I know it has something to do with DC biasing and the feedback on the circuit (as the capacitor will cause AC bypass). But I'm ...
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2answers
57 views
Is there a way to impose current with an amplifier?
I am trying to design a circuit to drive an inductor. I need to set an output current flowing through the inductor, and I want to set it no matter the resistance on the output.
I found some current ...
3
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5answers
242 views
Why is the internal resistance of BJTs considered in small signal AC analysis but not in DC analysis of BJT amplifiers?
Specifically, I want to know why "r" parameters are considered in AC analysis but not in DC. I am reading from Electronic Devices by Floyd.
For example, in the picture below, VB is ...
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2answers
186 views
Amplify 29 kHz signal
I generated a 29 kHz sine wave using an STM32 DAC periphal. The sine wave has 2.96 V output, but I need to make it at least 10-12 V. I tried using TL084, OP07CP, AD620 but the TL084 and OP07 don't ...
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0answers
59 views
Why does power driven to the load has this expression?
I'm designing an oscillator, I'm using as textbook Krauss one.
I would like to design the oscillator In function of the power it must give to the load and the fundamental frequency.
I have seen this ...
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2answers
26 views
How does a Touchstone (s2p) file indicate whether it should pass or block DC?
I'm trying to simulate impedance matches for an LDMOS FET amplifier with Touchstone (s2p) files to simulate the device with "real components" before we build it. I have found that "...
3
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1answer
72 views
Two stage amplifier, low gain at high frequencies
When I simulate one stage amplifier it is capable of amplifying to a much higher frequency than a two stage amplifier.
I added a 100 ohm resistor to reduce the gain of the two stage amplifier so both ...
0
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1answer
55 views
Low Pass filter using Parrallel components
I have a PCB design that I need to add a low pass filter. However I can only add components in parallel. It is going to be very difficult to cut the tracks or add components in series. Is there any ...
