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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1answer
20 views

Remove DC bias without phase shift?

Are there any circuits than can remove DC bias of an input signal without inducing a phase shift? I'm thinking for the input of an amplifier but whatever will work.
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1answer
49 views

Stereo channel strip based on NE5532

I want to build a stereo channel strip, using the NE5532 IC. It should feature 2 mono inputs with volume control, mute switch and pan control going to a stereo output with unity gain. In the schematic ...
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8answers
2k views

Is a transistor truly an amplifier?

My understanding of transistor is that in it a tiny current controls a huge current. I get that concept. If that is the case, it is not amplifying anything in my opinion. Sure it does dictate when ...
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3answers
202 views

Headphone amplifier: negative charge pump vs. phantom ground

I want to use a "capacitor-less" headphone amplifier that doesn't require DC blocking capacitors at the output. I found a headphone amplifier that has a negative charge pump that generates an ...
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2answers
425 views

QUCS simulation radio transistor amplifier

I'm trying to design a small amplifier for AM signals to use before the usual diode-C-R detection (the reception in my area is very poor). I devised a QUCS simulation as below: The diode and ...
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0answers
49 views

Difference between a lock in amplifier and an oscilloscope

I'm a physics student and in my lab we are currently dealing with lock-in amplifiers. So far the thing that I found out is that an oscilloscope displays a signal in the time domain and a lock-in ...
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4answers
281 views

Filter-Amplifier circuit for Low Voltage I/P circuitry

I'm designing my first ever circuit for a hobby project. I've a sensor that outputs in mV (1 to 2) and a controller with ADC. The ADC is 16 bits, VDDA = 3.0 V, Temp = 25 °C, fADCK = 1.0 MHz. Since the ...
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1answer
988 views

lock-in amplifier (AD630)

I ve got a signal that consists of 2 square waves at 2 different frequencies at the kHz range, about 10 Hz apart.I need to determine the relative amplitudes of 2 different known frequencies and I was ...
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2answers
467 views

Bluetooth receiver combining differential outputs to single ended (LR, N) to one (main) secondary amplifier

Hello I am new to this forum recently purchased a CSR8645 Bluetooth Module I have a Sony MHC GX Music system with AUX/MD Video Audio input (Left Right Ground). But in my CSR8645 ...
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2answers
107 views

I'm trying to build a Common Emitter Amplifier, but nothing is working

My transistor model is BCx19, and I'm trying to get a 10 times gain. I am honestly kind of lost. COuldn't get a lot of info from my teacher, I was just more confused when I asked him.
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1answer
64 views

What are the resistor values that I should use in order to get 38dB gain?

I have build a common emitter-common collector multistage BJT amplifier. I want to get an output gain of 38 dB under the conditions of 8 ohms load resistance, 6 volts, 25 mVpp input voltage signal. ...
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2answers
514 views

Choosing Collector Current for Transistor Amplifer

I see in the guides to standard Bipolar Transistor circuits (emitter-follower, common emitter amplifier), they always say: Choose a quiescent current of 1mA. How is this value chosen? I look at the ...
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0answers
43 views

Input to the Inverting terminal of an Op-amp [closed]

May I know what happens if I input DC voltage to the inverting input in a non-inverting amplifier.?
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0answers
36 views

Is it safe to leave the GND from an antenna jack unconnected from an active antenna amplifier?

I need help with trying to use properly this circuit, the original idea came from the late Tony Van Roon who designed it. According to the article it seems that the logic behind it is that the dim ...
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1answer
194 views

Split Audio lineout into two different amps

I am using a 3116d with a lpf and a 7498 for the mid range. The audio signal comes from a common source. The cables are split and soldered, so that both amps receive the same input. However, doing so ...
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0answers
42 views

How can I go about learning to output audio to a speaker using a STM32 board?

I am hoping someone can point me in the right direction. I am trying to learn how to output audio on a STM32 board. The board I have is the STM32F746ZG NUCLEO board. I have small (1-3) second audio ...
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2answers
419 views

Discrete Distributed Amplifier

I read about distributed amplifiers. I know they are used in MMICs, but I wonder whether it would be possible to build a distributed amplifier with discrete components. In my opinion, it would have ...
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1answer
766 views

Cascaded Amplifier Circuit Analysis Problem

I have this homework problem for my electronics class and I'm in need of assistance. Here is the original problem statement: This is what I have after drawing the circuit: My professor always ...
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0answers
48 views

How to sound-amplify my ESP8266

I've set up a ESP8266 to play MP3 radio from a web server, using the ESP8266 Audio library. My circuitry is pretty much like this: My question is, how can I amplify the volume of the sound, as it is ...
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1answer
257 views

Electret microphone amplification noise

I am building a circuit that amplifies an electret microphone with the use of an op amp. It does work, but I am getting a lot of noise at the output side of the op amp when I connect it to a pair of ...
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3answers
586 views

Irregular common emitter amplifier design

Would anyone know of any merits (or demerits) to the common emitter amplifier represented in Figure 1 in comparison to one of a regular pattern (Figure 2)? Thanks. (The 'DS548' transistor in Figure 1 ...
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2answers
68 views

Home Stereo vs. Music gear power rating [duplicate]

I see home sound systems rated at 300w, etc. but a 50w guitar amp is massively louder. I assume that the first one is some useless marketing rating, but how are the two figures calculated to be so ...
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2answers
163 views

Adding a potentiometer to an LM4910 as a volume control

Can someone tell me where I need to place a potentiometer to control the volume in this LM4910 amplifier circuit? Does the shutdown pin need a pull up resistor to enable the IC?
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0answers
35 views

What's wrong with my experiment to observe harmonics caused by receiver saturation and non-linear behavior?

I've been trying to devise an experiment to produce a third order harmonic in radio receiver that's been saturated, but I'm not seeing the expected results. My understanding of the theory is that when ...
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2answers
916 views

pam8403 using low wattage speaker

I am using the output of usb sound card as an input to PAM8403 ic with specs from datasheet. However i am using 4 ohm 0.5 W speaker. So i have tried testing with that and it works but sometimes with ...
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0answers
28 views

Which is the bandwidth of an analog PAM (needed to design an amplifier)?

in a university test, I've been asked to design an amplifier for the following signal: $$s(t)=\left[\sum_{i=1}^{\infty}rect\left(\frac{t-t_i}{T}\right)\right]\cdot Acos\left(2\pi f_0t+\varphi\right)$$ ...
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1answer
43 views

AMC1200BDUBR Gain is 4 instead of 8

I want to measure grid voltage with AMC1200b. I used a resistor voltage divider and I lowered grid voltage from 110v(rms) to 110mv(rms). I fed the 110mv(rms) signal to AMC1200b (for the first side of ...
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2answers
171 views

Is this IC damaged or fake?

I am trying to test a AD8307. Here are my connections: (pins not shown are left unconnected, and also pin 8). I get a quiescent output voltage at pin 4 of about 850 mV with respect to ground, which, ...
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2answers
315 views

Resistor on pin 3 of a Log Amplifier

I'm trying to understand what's the function or R2 resistor in this transdiode log amp configuration. I suppose I've to match the right value to give in order to minimize the effect of input bias ...
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10answers
20k views

LM394 is obsolete. What is the new standard log amp circuit?

The traditional logarithmic amplifier circuit is described in National Appnote 311: This circuit uses the difference of two transistor currents to generate the log of the input over a pretty wide ...
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2answers
240 views

Why are all log amp examples with common base logging transistors?

I am not experienced with log amps, and am trying to learn about them. Every log amp article has the base of the logging transistor grounded. simulate this circuit – Schematic created using ...
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1answer
51 views

Reverse the drain of a Channel - N Mosfet using a P - Channel Mosfet? [closed]

I am working on a school project which consists of converting audio signal into amplified pwm signal with a tda amplifier (raw) not a complete circuit with resistors and capacitors, then converting ...
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2answers
282 views

Ferrite rod antenna for DCF77 simulator

Where I live, in central Italy, the signal of DCF77 (the German longwave time signal and standard-frequency radio station, which operates at a frequency of 77.5 kHz) is so weak when it arrives, that ...
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2answers
92 views

Same output amplifier

Is there a amplifier that will always put out the same value? The values are ac not dc Example 1: 1 volt signal in=> 5 volt signal out. Example 2: 3 volt signal in=> 5 volt signal out. Example ...
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3answers
131 views

Low Pass Current to Voltage Amplifier with 2 Op-Amps

let's consider this two Op-Amp amplifier: From what I can understand, it consists of two amplifiers: A current to voltage low pass filter (at left) A non-inverting amplifier (at right) Well, there ...
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2answers
30 views

Error: Multiple analyses requested in LTSpice

I am running the following simulation in LT spice but I am getting the following error: Multiple analyses requested .trans 0 100m 90m 1m .op Here is my circuit. ...
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4answers
3k views

Is there a programmable variable resistor

I have a current signal that can vary in amplitude. I currently have a transresistance amplifier which uses 330 Ohm resistors. However the amplitude of this signal can vary and I would like to be able ...
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3answers
694 views

Output Filter Components Breaking Class D Amplifier Chip

Hi I am designing a class D amplifier PCB using the TPA3122D2 amplifier chip. I am planning to base my circuit on the schematic from the evaluation board: I bought components of the same values given ...
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1answer
830 views

Summing amplifier - output voltage and power supply

I have to solve a problem where a summing amplifier has AC and DC as inputs. I calculated the output voltage min and max with the formula: $$ V_{output} = \frac{R_{f}}{R}(V_{1}+V_{2}) $$ So I have ...
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2answers
338 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: ...
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1answer
208 views

Is the Gummel-Poon model useful for explaining AC transistor amplification?

Let me be clear: By amplification I am talking about the process of boosting the strength of an AC signal. Thus, where the output power to input power ratio is greater than 1. Now suppose we have a ...
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1answer
65 views

I'm looking for the right audio amplifier, but am lost in a maze as an unexperienced starter

Firstly thanks for helping out! The problem I am facing is that I have to power 24 audio exciters (2W max, 8 Ohm) from a microcontroller which is currently 5V but might be switched to 3.3V later on. ...
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1answer
44 views

Why an does an offset on the reference electrode create an offset on the measure electrode of a pH probe?

I am making an analog front end for a pH probe. I encountered a design where creating an offset on the reference electrode creates an offset on the measure electrode. How does that work? Does the ...
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4answers
1k views

Excessive noise in amplifier circuit when switching from DC power supply to AC-DC adapter

I'm working on breadboarding this amplifier circuit before transferring to a perf board. When we power it from an adjustable DC power supply set to 12V, the audio output sounds clear. When we switch ...
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1answer
41 views

Stability of a RF Amplifier

In this article a RF Amplifier Design is proposed. It's written that (page 2): In an RF transmission network, if the reflection coefficient of a certain port is greater than 1, positive feedback will ...
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1answer
86 views

Bypassing an AC signal in a common emitter amplifier without a bypass capacitor

We all know that we use a capacitor across the lower resistor (Re2) so that the AC will be bypassed through the capacitor and hence no (almost) AC voltage drops across the 2.7k. If that is the case ...
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1answer
62 views

How to prevent single rail ampliier power-on pop sound?

I would like to build a 9V battery powered microphone pre-amplifier and I'm encountering a design problem which I don't know how to solve: I have an opamp that serves as main amplifier which is ...
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1answer
398 views

How to convert from S-parameters to power gain?

With reference to the part below, which states 17dB gain at 500MHz for Vce = 12.5V https://www.digikey.co.uk/product-detail/en/stmicroelectronics/PD55003TR-E/PD55003TR-E-ND/1664253 It's data sheet ...
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0answers
37 views

Source Follower MOS based amplifier design

VDD = 3V, VSS= ground (0 V), use a current mirror circuit for the biasing. I want to design a source follower with a bias current of 20mA. And also I want to find its power dissipation, 3dB bandwidth, ...
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2answers
62 views

Is it a problem to connect a controlled current source in parallel to a voltage source?

Does a similar connection cause conflicts or damage? An example of situation in which it's used. I've seen it's common practice in RF to put an inductor (RF Choke) between the drain of a MOSFET and ...

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