Questions tagged [power-amplifier]

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1answer
49 views

Why are there three transistor pairs in Class B Power Amplifier circuit?

I have a Class B amplifier circuit to be done in lab. Why three pair of transistors are used in this? I suppose one is a Darlington pair but what is the requirement of the third one. Also, why there ...
1
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1answer
70 views

Calculate resistor to adjust base current in Class AB amp

I was tinkering with this "pseudo" class AB amp. The transistors have a minimum gain of 160. For now I wish to have an output of about 160 mA, which mean that I need 1 mA at the base of the ...
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1answer
103 views

Can I use a 100uf capacitor instead of a 1uf capacitor? [closed]

I am busy building a power amplifier module for a guitar amp. I used a 100uf capacitor instead of a 1uf capacitor at the input. When I connected the circuit to the output I did not receive the outcome ...
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2answers
150 views

Voltage divider getting HOT!

The scenario went like this: I used to run this amp with +-20v DC, and it seemed to work fine except for a little bit of clipping. Now, I changed my mind to make it work with bigger voltage!!! I've ...
0
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2answers
50 views

How can I use USB output (5V DC) to power a fan 12V DC load?

I would like to power a 5V DC/0.23A fan (beside another device such as 12V LED lamp, and 12V DC water pump). The only possible power source is using USB output, either from computer, mobile phone's ...
0
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1answer
94 views

How to substitute something modern for the TDA2003?

Application pocket radio, ham-radio transceiver. It has to connect standard microphone with speaker which couldn't be powered through differential pair of wires. Minimal specs single ended output ...
0
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0answers
74 views

Calculate actual power of speaker

I have a sound system: 8 speakers, 1 amplifier (4 channels). Speakers were connected in parallel. I want to calculate actual power on each speaker. Specifications: 8 speakers: Woofer (4): Power: ...
0
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1answer
31 views

Gain compression on an Ids vs Vds curve in Power Amplifiers

I haven't found a single document that talks about "Gain Compression" in a power amplifier referring to the typical Ids vs Vds curve. Books talk about a sinusoid "clipping" when showing these curves ...
4
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4answers
2k views

In a Class-C power amplifier, what does the resistor in the base do?

Look at the picture, which shows a Class C power amplifier (source). What is the role of the resistance in the base of the transistor, and what happens if it's removed?
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2answers
154 views

What makes LM386 so common at sound amplification

TL, DR at the end. Preamble: This quesiton results from an analog electronics lab project. However, I am not someone who asks here and wants you to do the job for me. Rather, I have been extensively ...
2
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1answer
36 views

RF Transmitter Impedance - Looking from the Transmission Line

If an RF transmitter is designed to transmit into a 50 Ohm load, is the impedance of the transmitter, when looking from the load towards the transmitter, always 50 Ohms?
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0answers
49 views

RFID spoofer with extended range

I have recently found this tutorial online about making a simple RFID spoofer, using only Arduino, used paper roll, coil wire and some passive components. I thought it was pretty neat and decided to ...
0
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1answer
50 views

Transformer Coupled Class A Power Amplifier

I have seen in some books, in the transformer-coupled Class A amplifiers The transformer is connected between the collector and the VCC. The transformer is connected between the emitter and GND (...
0
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0answers
25 views

Can anyone explain dynamic gain measurement (2 tone test) to check for the memory effects in the system?

I have read in a lot of research papers concerning RF-Power Amplifiers that they tend to have memory effects. It means that the current PA output depends on the memory of the PA along with the input. ...
0
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3answers
87 views

TDA2030L Audio distortion at high volume

I am using a TDA2030L audio amplifier to make my own subwoofer at home. The amplifier works well with the sound input (from a PC) at around 14 percent. The power input is 19V and 2A which is about 38W ...
3
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4answers
109 views

How to analyze the biasing of the output stage in this amplifier?

My textbook says that biasing current through Q8 and Q9 is about 20mA and through Q10 and Q11 about 100mA. How can I analyze the circuit to get these values with back-of-the-envelope calculations? So ...
1
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0answers
76 views

Struggling to get an amplified sine wave over a small inductor at low frequencies

I am building a power amplifier circuit to amplify a sine wave over an inductor from a function generator. However because the inductor is small and i'm running at a low frequency I am getting ...
1
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1answer
47 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 ...
1
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0answers
38 views

What is input to the RF power amplfiier (gate of the MOSFET)?

I have read that the RF PA is a block just before the antenna. So, the input to the RF PA (voltage signal at the gate of trasistor in the PA) should be a modulated signal and thus the PA just does the ...
0
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0answers
32 views

How to model RF-PA in MATLAB when the design values are given?

I have been given a designed Class-E RF-PA - the technology used for the MOSFET, the inductor and capacitor values attached to the MOSFET (as given in the figure below). I am suppossed to find the AM/...
0
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1answer
62 views

Circuit Definition

This is a circuit that I've found in my old amplifier board. Experts please help me identify this circuit and please describe how it works. I am sorry for my crude drawing, but this is what I found ...
3
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1answer
83 views

what is the difference between these two configurations?

I can understand this circuit configuration: But i don't understand when signal is placed in Qp's base. In this configuration we don't have VBB/2 in the two base... Sorry about my english and thanks ...
0
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2answers
68 views

Maximum Gain and Maximum Power Transfer

I am a bit confused about Impedance Matching for maximum gain and for maximum power transfer. I knew that the conjugate matching between, for instance, an amplifier's output port and a load Zl, is ...
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0answers
24 views

Question about pins on TCA940

So for the sake of learning i got this 10 watt audio amplifier and i wanted to see if i could make things work but i'm not sure what some of the pins are used for. Pin 5 "Compensation": From what i ...
4
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2answers
124 views

DC on op-amp input, audio amplifier

I have built the following audio amplifier circuit on a breadboard. The circuit works. However the circuit makes a DC offset on the non-inverting input of the op-amp. simulate this circuit – ...
0
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3answers
80 views

How to match a power amplifier and a loudspeaker array?

I am trying to use a power amplifier that is available to me to actuate an array of loudspeakers. The array has a total number of 30 loudspeakers (ways of connection can vary). And I would like to ...
0
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1answer
107 views

Class F amplifier analysis

I can't figure out why drain voltage is rectangular in the following circuit: I tried this: $$ V_{ds}=V_{DD}-I_{fund}R_lsin(\omega_0t)-I^{(2)}Z_{in}^{(2)}sin(2\omega_0t)-I^{(3)}Z_{in}^{(3)}sin(3\...
0
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1answer
99 views

Power amplifier design

For my research purpose, I am planning to design one power amplifier (basically, a current amplifier) with the following specification- Frequency range: 0-100MHz (or at least 0-30MHz) Output voltage: ...
0
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1answer
172 views

Amplify Arduino Due DAC output

I need to drive an inductive load from an Arduino Due analog output. The analog output delivers 0.55V-2.75V (yes, it doesn't deliver 0 volts). I need to get something like 0-14V with up to 3A ...
1
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0answers
52 views

How does speaker in “ROBOCOPP B A S U Ealarm SOS Personal Alarm” works?

I was working on a project which required producing a sound with more than 125 DBs...then I found this device in market which claims of producing 130DBs although to my knowledge it produces around ...
2
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1answer
60 views

Improving Power Amplifier - Digital Bias current set

In the following power amplifier: the MOS bias current is set by VR2. T4 acts as a temperature balance. The ensemble R15, RV2, D5, T4, T5, R14 act as a current source. VR1 act as offset adjustment....
1
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1answer
60 views

Calculation of DC power drawn by circuit in Class A power amplifier

simulate this circuit – Schematic created using CircuitLab I'm watching Prof. D.C. Dube's lecture (timestamp included) on power amplifiers, and I'm confused about the calculation of DC power \$...
0
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1answer
180 views

Unexpected loadline in ADS simulation

NOTE: This question is related to a homework project. I’m designing a PA for the 850-880MHz band. We have quite a lot of freedom for doing that. Only two requirements are specified: The amplifier ...
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0answers
71 views

how to enlarge the reading range between the 13.56MHz NFC reader and tags with ISO15693?

I use TI devices, DLP7970ABP and RF430FRL152H tag. In order to enlarge the reading range, I buy a power amplifier and a large antenna(430mm*330mm). If I only disconnect the original antenna on the ...
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0answers
83 views

Add IR (infrared) remote control to simple audio amp?

is it possible to add some kind of a remote control receiver to a basic audio amp board that only has a manual volume knob? The IC chip in the amp board is a TDA7498. A general view of the board is in ...
0
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1answer
157 views

Isolated High Voltage Amplifier Idea

Test laboratory of our factory asked me to design an isolated high voltage amplifier. Here are the requirements: The circuit will be built with transistors and passive components in the lab. (No IC ...
1
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1answer
112 views

How do I choose the power rating of resistors in audio power amplifier?

I read a bit about audio power amplifiers and struggle to understand the power rating of the emitter (i.e. current sharing) resistors in power amplifiers. I refer to this project. [EDIT: schematics ...
1
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2answers
148 views

Why should the bias servo transistor not be placed on the main heat sink for a Sziklai pair?

The Wikipedia page on Sziklai pairs contains the following statement (emphasis mine) Sziklai pairs can also have the benefit of superior thermal stability. [...]. [Q]uiescent current is much more ...
1
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1answer
49 views

Power amplifier shows 0 input and output resistance

I have a non-functioning transmitter for a radar I've built. When I was checking for shorts using a multimeter, I noticed that the resistance measurements between RFin and GND and RFout and GND of my ...
0
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1answer
92 views

alternative amplifier for vibration exciter (shaker)

I am using a second-hand LDS V201 permanent magnet shaker, and would like to use this to test and validate some monitoring equipment. I would like to generate signals suchs as sweep sines, but these ...
0
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1answer
55 views

Calculate input resistance of power amplifier

how can I calculate the input resistance of this circuit? Thank you!
1
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0answers
79 views

Amplifying pulse signals causing pulse lengthening problems

I am currently trying to design a circuit that would sense a voltage change at its input, convert that change into rapid "on"/"off" change at output and amplify same switching voltage to high current (...
0
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2answers
190 views

Power Amplifier (Darlington) with Power and current limitation

I'm designing a power amplifier and the following circuit is the output stage. My output stage consists of two complementary transistors for both, positive and negative waves but for better ...
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3answers
155 views

Power amplifier, does this circuit work?

I found that circuit for a power amplifier. Does it work? I want to build one for myself.
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0answers
72 views

Built-in power amplifier of the ST7580

The ST7580 is a power line communication device that can be controlled with any host controller. The ST7580 has a buil in power amplifier to allow it to send a modulated signal (0Hz to 250kHz) as far ...
2
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2answers
441 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 ...
2
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2answers
72 views

Question about the power rating of a RF power amplifier

In HMC453ST89's datasheet, it gives the electrical specifications when Vs = +5V: The max. output power is around 32.5dBm, about 1.6W. But for a 50 Ohm load, 1.6W means the peak voltage is about 12V. ...
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1answer
150 views

How close to P1dB can I go?

I'm trying to decide on a safe input power to a power amplifier. The amplifier in question is SE5004L. The datasheet specifies that the amplifier output 1-dB compression point has a minimum value of ...
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2answers
154 views

Stk086 distance between pins? [closed]

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 ...
1
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1answer
1k views

IR2110 driver output causing shoothrough despite deadtime

I'm having trouble with the ir2110 output. I'm working on a class d full bridge amplifier and I use 2 ir2110 to drive 4 irf540N mosfets. The switching frequency I use to generate the PWM is 240kHz and ...