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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27 views

Deliberately Blowing Up an LM386N-4 Power Amp

This is a somewhat unusual, although hopefully not too irresponsible, question (I also hope it falls within the remit of this site, I can't think of anywhere else online where I'd get a trustworthy ...
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1answer
34 views

How to operate Op-Amp[OP07CP] with 0-5v supply?

I don't know why I cannot operate Op-Amps! this is my second circuit and I'm trying to make a non-inverting amplifier by an OP07CP. This is my circuit + an example of measured values: simulate ...
0
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1answer
57 views

Transistor Amplifier Circuit

I need your help Given: AC beta (Bac) = 160 Ie = 3.8 mA Find : a) Rin (TOTAL) b) Rin (BASE) c) Av (voltage gain) I am uncertain of the process. I have Rin (Base) = Rs + R1||R2 or is it ...
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1answer
45 views

Sampling many low voltage analog signals

I'm trying to sample 128 low voltage (a few millivolts) analog signals at around 800 samples/second. My original idea was to hook up 128 instrumentation amplifiers to 128 ADCs, but that turned out to ...
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2answers
47 views

Need help with adding volume control to op amp!

I am trying to add a volume control to this audio headphone circuit I found online: As you can see, there are two 470k ohm resistors on the input signal. Here is my circuit that I created based ...
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0answers
12 views

Why does lower conduction angle of an amplifier leads to higher efficiency?

I know that conduction angle is the component of an input sine wave where the amplifier is conducting. For some of the amplifier classes, class A has a conduction angle of 360°, AB has an angle ...
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2answers
65 views

My non-inverting amplifier doesn't work correctly (the Gain isn't correct) [ICL7650S Op-Amp]

I'm working with ICL7650S(online datasheet). I made a non-inverting amplifier but I don't know why the Gain isn't correct! this is my circuit: The Gain should be (841k/2.14k)+1=393.99 but when ...
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1answer
44 views

Help with Amplifier Circuit

How can I analyze this differential amplifier circuit? I need to find the differential gain, the common mode gain and the CMRR (common mode rejection ratio). And is the schematic okay? The amplitude ...
0
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1answer
21 views

Electrophysiology amplifier problems (electrode design help)

I have been working on a small differential amplifier that will ultimately be used for whole nerve recording from lobster connectives. Throughout the process I've been testing the amplifier using ...
0
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1answer
23 views

Limited Wien-Bridge Oscillator Amplitude

I've already seen a similar question but the circuit was a little bit different. My question is simple: how do I calculate the maximum amplitude of the oscillation at Vo, as a function of the ...
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1answer
59 views

High Frequency, High Power Amplification

I was wondering if anyone could give me a little information on amplifiers. What would be the best way to amplifying a small, 1v @ 1mA, very high frequency signal (3-5MHz) to a high power signal? The ...
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1answer
39 views

Class J RF Power Amplifier

What is a Class-J Amplifier configuration? Does it work in a push-pull configuration similar to an A/B? How is it physically different to an A/B? Where can I see a basic schematic? I have read ...
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2answers
58 views

How to amplify both phone audio channels in this case (infrared remote)

I'm a photographer and have limited knowledge about electronics. recently I saw this circuit: which is explained here I tried to Build it, it works fine on my laptop jack, but does not work on my ...
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2answers
92 views

Why these can't be an amplifier? [closed]

I am asking if we have a voltage signal must be amplified why we can't mount it in a resistance less than one and take the output as a current by using Ohm's law I = V/R and R is less than one ?
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0answers
50 views

Explain this exercise to me?

We have the CM half circuit in the figure. I understand that $$A_\text{cm}=\frac{(\alpha\times R_\text{c})}{(2R_\text{e}+ 2re) }$$ but how is this equal to $$\frac{2}{8.65} $$ like it's solved in ...
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1answer
46 views

Finding amplitude and phase response of an amplifier

I have a following problem, I have to find amplitude and phase response of an amplifier whose function is $$ H(s)={\frac {1}{s^2 + s + 100}} $$ I have solved simillar problems such as for this ...
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0answers
30 views

Operational Transconductance Amplifier Input Configurations

I recently purchased several OTAs (Lm13700) but have had quite a bit of trouble using them. Going through the TI datasheet and a Nuts & Volts tutorial it's occured to me that transconductance amps ...
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0answers
31 views

PIN Diode T-R Switch for use with RF Power Amplifier

I would like to use PIN Diodes to actuate the T-R switching of my RF Power Amplifier, however, I am having trouble understanding the proper way to accomplish this. I would rather use a solid state ...
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1answer
68 views

Can a resistor create current?

Say I have a boost converter, and the boost converter is outputting 5vdc, but it's not outputting the current or Amperage that I want it to output. Could I put a single resistor before my load, say a ...
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2answers
50 views

Problem with using comparator to amplify signal

I want to use LM293(comparator) to amplify signal. The input signal from 0 to 2.5V, and make the output signal double(from 0 to 5V). Then I use the LM293, and I do the simulation first, it works ...
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3answers
53 views

When multiplexing audio do I need a pre-amplifier for each channel?

I am building a 16 channel multiplexer which will deliver the input from 16 microphones to a single ADC. I am clocking the ADC at 1.6 MHz and therefore sampling each audio channel at 100 kHz. The ADC ...
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3answers
60 views

Why is voltage output inverted between common-emitter and common-collector amplifiers?

My resource shows the following common-emitter transistor configuration and claims that the output voltage compared to the input voltage is inverted (higher input voltage means lower output voltage): ...
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1answer
63 views

How do I change the output volume of this audio amplifier circuit?

In the circuit below, where would I place an audio taper potentiometer to modulate the output volume level? Which of the resistors should get replaced with the pot and why? If understand ...
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2answers
25 views

Relation between reflection (coefficient) and bandwidth

I am reading into single stage microwave amplifiers and how to design for a specific gain (source 1, source 2 warning PDFs!). In both sources the claim is made that the highest bandwidth is achieved ...
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0answers
42 views

variable gain amplifier for ACS712 current sensor

My project requires measuring current ranging from 30mA to 500mA. Im using ACS712 (5A)current sensor for this purpose. Since the sensitivity of the sensor is typ:185mV/A, measuring current as low as ...
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1answer
19 views

Explanation for stability criterium microwave amplifiers

Given a general microwave amplifier circuit For this amplifier (transistor) to be stable the the magnitude of the input and output reflection coefficient must be smaller than 1. But why? What is ...
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1answer
57 views

amplifying 555 astable multivibrator output [closed]

I am using 555 as astable multi-vibrator and its output is a square wave of 7 V and frequency is around 800 kilo hertz.But i need to increase the voltage to about 40 V . What should i do? Actually ...
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2answers
69 views

Why Doesn't This Op Amp Preamp Circuit Amplify?

I have the following circuit as part of a class D amplifier: simulate this circuit – Schematic created using CircuitLab I couldn't get the amplitude of Vsig to display, it is ~.447Vp, to ...
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2answers
349 views

How to figure out which transistor amplifies the signal?

Suppose I have the following circuit: How can I determine which transistor amplifies the signal and which transistor is just a simple resistor? Also if is a resistor how can I determine it's ...
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0answers
82 views

How to measure microvolts of electricity in plants?

I'm trying to measure electricity in plants, to do something a bit like this: http://www.treehugger.com/culture/organic-electronic-sounds-from-plants-sonic-artist-mileece.html Basically, plants ...
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1answer
42 views

Drive stepper motor with audio amplifier?

I am as a beginner in electronics contemplating how to build a motor driver for a stepper motor. From what I have read, the more sophisticated drivers will have a feature known as micro stepping ...
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0answers
60 views

Discrete BJT Voltage Controlled Op-Amp

I recently asked about building a transistor controlled variable gain differential amplifier for a project I'm working on. The configuration I used was less than ideal and I am researching different ...
1
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1answer
48 views

Differential gain of amplifier with current mirror

Consider this pdf document, pages 58-59-60. It is a differential amplifier with a current mirror as active load. According to that document, if I take the unbalanced output in the right-hand branch ...
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1answer
38 views

Getting bad clipping issues with this 3 stage amplifier

What am I using? 3 stages of amplification. An input voltage of 10mV peak or 20mV pkpk into the first stage. 1st stage: NJFET Common Source. Using a voltage gain of 3. 2nd stage: NPN BJT Emitter ...
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0answers
41 views

How much can BJT parameters (particularly beta) vary for Monte Carlo analysis

Background / Requirements: I'm designing a typical Class AB amplifier using diode-connected BJTs to achieve the biasing. I have a requirement to keep the total quiescent current at room temperature ...
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1answer
83 views

Difference Between LM386 and LM741 [closed]

What is the Difference Between the Normal Opamp LM741 and the Audio Power amplifier LM386.. I mean in both the circuit we use the concept of voltage compensation, then how come LM386 is called power ...
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1answer
48 views

Replacing an instrumentation amp with an op amp

I want to join a Load Cell (LoadMaster SPL 149 80) with arduino uno. Whenever I search online, I find INA 125p amplifier in the circuit but I want to know if there is an alternative to INA 125p ...
2
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1answer
101 views

Can you identify this Bose car amp burned part? [closed]

Many more pictures here The radio and amp stopped working after a battery jumpstart. I fixed the radio by simply changing a fuse but the amp has a burned part. I tried contacting Bose to no avail. ...
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0answers
46 views

Magnetic field detector

This Below circuit has been taken from talkingelectronics.com please tell me that Why is first resistor 1 mega ohm the second is 100 k ? what formula has been used in this circuit to calculate first ...
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1answer
43 views

Viability of Voltage Controlled Amplifier circuit

As part of the synthesizer project I have been working to design a simple voltage controlled amplifier. Due to the complexity of other parts of the circuit and the amount of time I've spent on this ...
0
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3answers
50 views

Virtually grounded negative input op amp exists but no virtually grounded positive input. why?

If the positive input of an operational amplifier is grounded, the negative input is said to be virtually grounded and it has therefore zero potential. But the contrary is not true. A grounded ...
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1answer
19 views

How do I find transconductance gm in this exercise?

We have the following exercise : I have questions regarding a) and b) For a) the solution is As for b) you can kinda see it in the above solution that IE=0.5 mA ,I think that this is because ...
2
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1answer
55 views

Buffered feedback circuit analysis

I saw this circuit while going through some circuits and have been trying to solve it since. I get confused at multiple points while solving for the current. Since there is a buffer for ...
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0answers
39 views

ADC amplifier gain dependence on microcontroller operating voltage

I was just curious about how dependent the gain of an internal ADC amplifier of a microcontroller is on the supply voltage? The variation I was thinking is 3.3V instead of the values given at 3V. The ...
1
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1answer
32 views

connecting a GSM booster directly to a mobile device? [closed]

I live right on the edge of mobile reception. I just get a signal with an external antenna, but it is weak. I am thinking of getting a small indoors GSM booster, like this. I was wondering if it ...
3
votes
2answers
217 views

Different roles of a resistor

I graduated in Physics, then fell in love with electronics, so, in the past few months I have been trying to make heads and tails from it on my own. Today, as I was reading about amplifiers I got ...
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1answer
44 views

How do I select transistors for logarithmic amplifier?

I need a logarithmic amplifier and found this equivalent schematic in the datasheet for the LOG104: The LOG104 is rather expensive, so I want to build this myself. What are the requirements for the ...
0
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0answers
13 views

How to stream audio over bluetooth to a device, use a bluetooth modeule with AVR atmega32?

I am trying to finish off a project I am working on that consists of an AVR atmega32 MCU and an on-board op-amp for audio amplification. Currently the device uses a hard wired connection for an audio ...
0
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1answer
53 views

Insight on analog and digital Lock-in amplifiers operation principle?

As far as my knowledge goes, in the analog case, the discrimination of the, low S/N ratio, signal is done by (demodulation) comparing it to local oscillator with almost identical frequency and then ...
0
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1answer
65 views

EEG amplifier circuit low and high pass filters. Oscillations, noise, etc

I designed a EEG amplifier circuit for for EEG signal amplification and filtering. Because I never had any experience in filters, It would be highly appreciated if someone could check my design. In ...