Questions tagged [class-a]

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How to implent a LoRa class A by Arduino?

I'm trying to make communication between multi node and one gateway using Arduino Uno and LoRa(SX1278). I read from "LoRaWAN® Specification v1.0.3" document that in class A, every endnode ...
2
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1answer
302 views

Why do I have clipping in this emitter follower

I am trying to design a class A amplifier buffer stage (I know it is not efficient.) I am starting from the simple emitter follower and the next step is to replace the RE resistor with a current ...
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1answer
65 views

Complementary pair - Role of capacitor on emitter

I bought this little kit for a class AB amplifier. The second stage is quite clear (and typical), but I am struggling to understand the role of capacitor C2 on the emitter branch in the first stage. ...
5
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3answers
664 views

Cascading common emitter and common collector

I am trying to design an amplifier for a 1 W 8 ohm speaker for educational purposes. The idea is to start from a common emitter amplifier to amplify voltage and then add a common collector (emitter ...
0
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1answer
51 views

Kirchoffs Laws and Class-A Amplifier Circuit

I have been attemtping to use Kirchoffs laws to solve a Class A amplifier circuit containing a single transistor. I made several attempts at this trying slightly different approaches. I summarized the ...
1
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1answer
76 views

Designing simple class a amplifier using mosfet

I'm trying to build a simple class a amplifier using a mosfet. I have read few articles about how to do it, but I'm just confused now. I'm not sure how to select resistor values. The articles I've ...
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2answers
59 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 ...
5
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2answers
342 views

Low power tube headphone amplifier design

I have never worked or even listened to tubes/valves before, so its about time I did. I wanted a simple design to work with being my first tube project, and have found this from diyaudioprojects.com: ...
0
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1answer
375 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
142 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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4answers
624 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 ...
4
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1answer
256 views

Presence of Crossover Distortion in Class A Amplifier

This question is about theory facts of class A audio amplifier. It is known that class A amplifier is usually biased so that an amplifier's quiescent point is in the middle of the amplifying device's ...
0
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1answer
338 views

Class A amplifier with preamp design

I am currently working on a class A audio amplifier designed to work with line in voltage (about -400mv to +400mv). I plan on using an IRFP240 for the mosfet but am undecided on the transistor stage. ...
2
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4answers
818 views

Class A amplifier - Transistor Q-Point calculation

Reference: http://www.learningaboutelectronics.com/Articles/How-to-find-the-q-point-of-a-transistor-circuit I am trying to understand this q-point calculation. I recently asked a question about the ...
3
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4answers
888 views

Class A Amplifier Design: Emitter Resistance Voltage Drop

I am trying to understand the design principles of Class A amplifiers, primarily for audio purposes. I have read several times that "the voltage drop across the emitter resistor should be in the ...
1
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1answer
278 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 \$...
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1answer
88 views

How to design a simple current based class A amplifier

Very much along the lines of Class A single transistor amplifier with 2N3904, but with a current signal input. My circuit is a Zener noise source using the simplest of components. Traditional class ...
-2
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1answer
475 views

Why does my amplifier turn sine waves into square waves? [closed]

All photos, schematics and the ltspice simulation file are in the folder. https://drive.google.com/folderview?id=1N1yKGnoWQoaGsuHla0DwJwF36_21ZBgX Hello! I have made a simple class A amplifier, but ...
6
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2answers
609 views

How to keep current from draining out the bottom of this push-pull amplifier?

In an earlier question I asked about driving a speaker with a BJT transistor. @Jonk offered a push-pull amplifier design of his own, and @G36 noted its similarity to the JLH amplifier described in a ...
2
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1answer
264 views

Class A Audio Amplifier

I am trying to design a Class A Audio Amplifier with the following specs: 9V DC Power Supply, Maximum withdrawn current 15mA Used with a Low Impedance (8 Ohm) Speaker Provide a minimum variable gain ...
6
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4answers
3k views

BJT base connected to ground and still operates?

When in university I used to get confused how a transistor (NPN) can draw current from ground. I'm now studying power amplifiers and again, this same configuration appears. How does Ir draw current ...
2
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2answers
5k views

Why can't class A amp drive 8 ohm speaker with just one BJT?

I designed this class A amplifier. It's my first attempt at designing an amplifier with transistors. My objective is to build a guitar amplifier with tubes, but I figured that building an amp with ...
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2answers
727 views

Can any type of op amp output stage be forced into Class A operation?

I'm trying to choose a good op amp for a Class A small signal audio amplifier circuit. I've done my research and understand the use pull up or pull down resistors externally to force Class A ...
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0answers
146 views

Simple Class A Output Power Stage of Amplifier

I made this circuit and the output signal wasn't really what I was expecting to be. simulate this circuit – Schematic created using CircuitLab This is class A amplifier (both Q1 and Q2 ...
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1answer
100 views

Balanced Class A Quiescent Current Regulator (OPS of Amplifier)

In my book there is a circuit like the one shown bellow. The author (G. Randy Slone) explains the operation and performance of it but there is still one thing that left me wondering. simulate this ...