Questions tagged [power-amplifier]

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60 views

Chaining Power Amplifiers

Problem I found an old (but not in use) garage door controller. The receiver is still intact but can't be reached from souterrain. The sender transmits a single tone on 27MHz in the citizen band. The ...
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2answers
59 views

How do you match an LDMOS FET to 50 Ohms?

I'm considering using one of the following LDMOS FETs as an RF amplifier: AFM907N (8W) AFT05MS031NR1 (30W) AFT05MP075NR1 (70W) The datasheets provide \$Z_{source}\$ and \$Z_{load}\$ metrics for some ...
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0answers
34 views

Can 2 amplifier support by 1 preamplifier?

Can 2x 5v Digital Amplifier work with 1x 3.5-5v Audio Receiver Preamplifier without any risk? Can the Preamplifier chip burn out because of 2 amplifier connected to it? If the chip can burn out what ...
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0answers
48 views

Step response of Power amplifier

i have the parameters for this linear amplifier Swell rate >52 V/µs Bandwidth DC … 5 kHz Power 3 × 30 kVA rise time at nominal voltage (230 Vrms) is 5 µs. and the transfer function is: $$F(s)=e^{-0....
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0answers
59 views

3W/6W audio amplifier using TDA2003

I am trying to build an amplifier circuit using TDA2003, I found a common type of circuit for this purpose in almost all the websites. I tried building it in Multisim and after some seconds of ...
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0answers
28 views

Load spread metric issues in power amplifiers

Power amplifier saturation or maximum power depends a lot on the load seen by the collector or the drain of the amplifier. If the load impedance varies across frequency, how serious is this in terms ...
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3answers
80 views

Eliminating an earth / ground loop in an A/V set-up

I have an A/V system with two active sub-woofers. One is close to the amplifier connected with a 1m RCA cable. Its mains connection is into the same power strip as the amplifier. There will be an ...
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2answers
56 views

Wiggle in the current source of an emittter follower amplifier

This has been bugging me for days. I still don't understand why the book says the current I through Q1 remains constant when there is a varying input signal at the base of Q1. Some peeps here also ...
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2answers
49 views

Class A Emitter follower instantaneous power

I don't quite understand the explanation given in the book I'm reading. Why the maximum instantaneous power dissipated by Q1 is P=2Vcc*I at RL open? Also, why is the current ic1 constant I? Wouldn't ...
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1answer
48 views

How can I choose the resistors for a push-pull class AB amplifier (diode biasing) to get a certain bias current?

Hello guys, this is my very first question. This is a part from a BJt audio amplifier volume control with 3 stages (Pre-amplifier,Buffer, & Power amplifier). This is the power amplifier stage. I ...
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0answers
50 views

Darlington transistors killing the output

I was trying to recreate a subwoofer following this website. And the first 2 stages function as expected. The low pass filter is working which i verified , and the the second stage amplifies the peak ...
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3answers
63 views

Class AB power amplifier output signal

The way the input source is applied to the Class AB amp, it seems that there should be no output that appear. Because when the input is positive half cycle, the diode D1 is reversed biased, there ...
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0answers
44 views

Class AB power amp DC bias at the emitter

I tried using KVL to prove that indeed the DC bias at the emitter of both Q1 and Q2 is Vcc/2. The following assumptions I made are: R1=R2 D1,D2 and the Base-Emitter diodes of both Q1 and Q2 are ...
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0answers
34 views

Common ground for subwoofer-out

I have a Sony Sony DSX-A110u which is a car stereo having 4*55W Speaker out and a Sub-woofer out. The subwoofer-out port it a female RCA jack. which looks like this - I am using the sub-woofer out ...
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0answers
33 views

Drawn current from a two and single supply Class B power amplifier

I was reading a section from a book that talks about class B amplifier. I don't quite understand what the author meant by the highlighted part. Can someone help me picture what the author is trying to ...
2
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1answer
43 views

Emitter-Follower Class A amplifier

I was trying to solve a problem from SEDRA-SMITH book. I got stuck so I refer to the solution. When Studying how the author solved the problem I got even more confused. Let's refer first to the ...
1
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1answer
41 views

Help check amplifier stability

I need to do the stability analysis of my amplifier circuit. I implemented schematic in LTspice, where I did some of simulations, so I would like to keep the same tool also for the stability analysis. ...
1
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3answers
102 views

In a class C amplifier, how does RB biases the base of transistor?

In a class C amplifier, I read that: "Resistor Rb is connected to the transistor Q1 base. A biasing resistor which connects to the base of Q1 try to pulls the base of transistor further downwards and ...
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6answers
6k views

Why is it possible to have undistorted power amplifiers?

In Albert Malvino's book "Electronic Principles," he says there is a 10 percent rule for small signal amplifiers wherein the AC signal current must be less than 10 percent of the emitter current so ...
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1answer
67 views

Why is a square wave used for audio power calculations?

I am trying to read this datasheet (NXP TDF8546 Class AB Power Amplifier). On page 12, the power calculations are mentioned as Po(max): RL = 4 Ohm, Vp = 14.4V, Vi = 2 V RMS Square wave As far as I ...
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1answer
54 views

Replace amplifier IC with a class D amplifier (AN7133N with TPA3116 board)

Today I received this nice 90's Panasonic RX-CT900 boombox in the mail. The specs claims it is 2x60W PMPO (PMPO b**llsh*t throw-of- a-cliff specification) but in fact it is just 2x5.5W RMS (...
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4answers
99 views

Audio power amplifier improvement

I need someone to revise/suggest improvement for the audio power amplifier I am designing. This PA is going to be used for driving the horn speaker (8ohm 100W). I decided to start design from scratch ...
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2answers
40 views

What is the appropriate capacity of a matching step down transformer for a power amplifier?

I have a TRIO KA-9900 amplifier which is the Japanese equivalent of a KENWOOD KA-907 amplifier. My amplifier runs on Japanese AC voltage. What is the appropriate capacity of a step-down transformer ...
1
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1answer
60 views

Can 3Ω speakers match 4~16Ω amplifier? [closed]

I have a set of Samsung home theatre system. The Samsung DVD player is no longer working. I would like to get a new amplifier and reuse the 5 existing Samsung speakers. But the existing speakers are ...
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0answers
62 views

Horn power amplifier design

I need to design experimental prototype of power amplifier (PA) for a horn speaker. The PA should support 100W RMS @ 8ohm. Power supply voltage is 12V. My first (and probably most simple) idea was to ...
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1answer
75 views

HiFi amplifier stages design

I have read some articals about design of Hi-Fi power amps and from what i understand most of the amplifiers use 2-3 or 4 stage amplification while 3 stage is most common (trans-admitance -> trans-...
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2answers
96 views

How to play music on PAM8610 with ESP32?

I'm trying to use Xtronical's DAC audio library on an ESP32 to run 10W speakers. The board that Xtronical used is a PAM8403 which has a signal voltage range of -0.3V to +0.3V but as it can only run 3W ...
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2answers
68 views

lab PSU based on a single power amplifier?

OPA548 op amp is a power amplifier capable of delivering 3 A at the output and limiting the current. at page 14 of the datasheet (figure 16) shows the schematic of a variable power supply based on ...
2
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2answers
103 views

RF Power Amplifier outputting insufficient power

I'm using an SE5004L 5GHz power amplifier to generate a transmission signal in a radar application. I've designed the output power of this amplifier to be about 26dBm. Unfortunately, the measured ...
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0answers
115 views

How to calculate the gain of a BJT Differential Amplifier (Long Tailed Pair)

I'm currently reading Designing Audio Power Amplifiers by Bob Cordell. After seeing the "Basic 50W Amplifier" that he shows in the beginning of chapter 2, I now am trying to use the same building ...
5
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4answers
9k views

Why is it preferable to use NPN transistors for both high-current-output devices in a push-pull amplifier?

With reference to the below circuit why is it preferable to use NPN Silicon transistors for both high-current-output devices in a push-pull amplifier?
2
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1answer
94 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
86 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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2answers
162 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 ...
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2answers
202 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 ...
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1answer
173 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 (...
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0answers
85 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: ...
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1answer
41 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 ...
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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
333 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 ...
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1answer
41 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
53 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 ...
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1answer
246 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 (...
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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. ...
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3answers
174 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 ...
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4answers
216 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 ...
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0answers
95 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
51 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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0answers
42 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 ...
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0answers
35 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/...