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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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2answers
1k views

Short circuit protection in simple audio current amplifier

In my class, we are to design a current amplifier with short circuit protection. In our design, we utilized 2 emitter follower amplifiers (Q3, and Q1). We then added Q4 and Q7 to lighten the current ...
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3answers
8k views

DIY simple line out converter for “floating ground” car head unit?

On a 25W max power (10V p2p @ 4ohms) balanced (push-pull) high level output factory car audio head unit from which I need to feed a mono amplifier (for subwoofer) that only has an unbalanced line ...
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1answer
393 views

How do I get 15V from a 34V power supply?

I have an audio amplifier with a regulated power supply putting out around 34V DC. I would like to add a preamp which requires on 15V. How would I draw 15V from the main power supply?
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2k views

100W Low Pass Filter

Currently I have a 60W amplifier for the 400-500MHZ band with a 50Ω impedance. In order to prevent jamming other frequencies I will need a low pass filter to block any frequencies above 500MHZ. I just ...
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2answers
211 views

Is there an amplifier such that the gain is equal to the ratio of two potential differences?

I have been toying with some alternatives to transistors in building logic gates. I am particularly interested in the device I tried to summarize in the title of this post. The chip would have 8 pins: ...
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2answers
771 views

Flipping a signal

I've an input of two input lines, one being connected to ground and one carrying the signal (measured to ground). The output should be three lines with one being ground and the others measured in ...
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1answer
4k views

How does transistor amplify current? [duplicate]

Possible Duplicate: I don't care how a transistor works, how do I get one to work? Basic questions about transistor amplification I have heard transistors are used in many electronic ...
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5answers
60k views

Simple Audio amplifier Using Transistors

I would like to build a simple audio amplifier using transistors. I know there are IC designs specifically for the task. But i want to use transistors so i can learn how to use them for amplification. ...
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2answers
2k views

1.8v GPIO controlling 5v 10mA solid state relay

I have a Crouzet 84 134 900 solid state relay that I need to control with a 1,8V GPIO output from a Gumstix Overo Summit expansion board. I've tried the circuit drawn up for me in this answer, however ...
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2answers
253 views

Is it possible to mod a class 2 bluetooth device to work as a class 1 device?

I have two Microcontrollers which communicate over a bluetooth link (serial link, like RN-42). So far so good. Unfortunately the device is listed as a class 2 device and I noticed that the distance is ...
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6answers
12k views

Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV ...
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2answers
1k views

Capacitor in parallel with resistor on xoscope amplifier schematic

Short version: Why is C3 necessary in this circuit? Explanation: The schematic for the input buffer/amplifier circuit for xoscope is made up of subsections that are mostly broken down in the ...
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3answers
3k views

Question about the output voltage of an op-amp. (ua741)

When i hook up my opamp to a 9 volt battery (like in the image below), i get 8 volts from the output pin. It gives the same reading when i attach both the inverting and non-inverting pins to the 9 ...
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2answers
2k views

Noise when powering headphones amplifier through USB port

This question is actually connected with this one: Getting 1.2V from USB I've successfully connected my FIIO E3 headphones amplifier to USB (so that I don't have to use batteries). But I've notices ...
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1answer
556 views

What type of amplifier do I need for this project?

I'm trying to make a custom PA system for my car, but I am confused about what type of amplifier I might need, or do I need one at all? I'm wanting to take the main sound unit out of a "personal ...
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1answer
354 views

Adding microphone/amplifier to Gumstix Overo Earth COM?

I am new to hardware hacking in general. I have a Gumsitx Overo Earth COM and a Palo35 expansion board with audio in/audio out capabilities. According to Gumstix's wikipage on audio input, the ...
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2answers
1k views

What's a reference text on analog design?

I'm looking for a intermediate text that covers (discrete) amplifier circuit theory using BJTs and FETs and circuit elements such as current mirrors, differential stages, feedback theory, etc. My ...
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1answer
1k views

How to measure battery voltage

I am building a battery powered device. Almost all of my logic is running at 3.3v, although I do have a 5v supply for a few hobby servos. I want to measure the battery voltage, but I can't do so ...
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2answers
2k views

mute de-amplify sound volume

I want to de-amplify the sound volume of my television. My native language is not english, and I do not know the correct word, if any, for the opposite of amplify. When my TV is turned from volume ...
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2answers
2k views

How can I attenuate any signal to 5V peak-peak?

How can I attenuate any signal to 5V peak to peak? I tried the following design : While I limited the output to 5V peak-peak, the circuit clipped the output to 5V instead of attenuating it. My ...
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2answers
225 views

3.5DB splitter loss in voltage?

I am trying to figure out the loss from a cable splitter. I am assuming it is analyzing any other filter circuit. This should equals a loss by a factor of 1.5 or is there some special nomenclature for ...
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2answers
1k views

npn transistor base current question

Hi i am new to using transistors for signal amplification. Can someone explain to me how to figure out the amount of current being drawn into the base of the transistor when it is in the common ...
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2answers
732 views

Circuit to exaggerate differences in current

Basically what I am after is some sort of a circuit which will amplify higher voltage signals, but possibly dampen lower voltage signals, in order to make a wider separation between high and low ...
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1answer
611 views

Circuit diagram and components for Comfortron controller (Chevy, Oldsmobile, …)

I am trying to help repair a Comfortron heating and cooling controller for a late 1960's Chevrolet Impala. The Comfortron is an early climate control system that uses a combined vacuum and electrical ...
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5answers
4k views

Differential amplifier - what is the differences between CMRR and CMR?

I know that CMRR is Common-Mode Rejection Ratio, but what is CMR? $$CMRR = \dfrac{A_{dm}}{A_{CM}}$$ I didn't find any mention of it in Sedra & Smith bible. Does anyone know what CMR is?
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1answer
284 views

What is the best way to remove the non-rejected portion of a common-mode voltage and any bias voltages from a differential voltage measurement?

I am using a high-common mode differential amplifier (AD629) to measure several DC 10 to 15 voltages stacked together. Since the AD629 is not the cheapest amplifier in the world (though not as ...
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3answers
1k views

LM386 output signal problem

I've built a signal generator (with an Arduino) what can output 18kHz and 19kHz signals (separately) and it's connected to a speaker. This works just fine, there are no signals on awkward frequencies. ...
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2answers
531 views

Theoretical analysis of amplifier circuit

I have the circuit of the amplifier below. I want make the DC analysis and find the gain the amplifier produces and the cutoff freq(high-low). My problem is that it's been 15 years since I was ...
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2answers
40k views

Difference between cascade and cascode?

What is the difference between cascode amplifier configuration and cascade amplifier configuration?
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2answers
6k views

Amplifying and filtering a very low frequency signal(Bandwidth of 4Hz)

Good night, everyone. I want to amplify and filter a signal that has a bandwidth of 3.5Hz and is of the order of 5 - 40 milliVolts. I plan to amplify the signal before filtering it so as to prevent ...
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3answers
2k views

Does this amplifier work with 5V?

I'm using an Arduino to read an analog signal from an electret microphone. Here is the circuit: But I will be powering it with 5V from the Arduino, So would this work okay? Thanks!
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3answers
7k views

Audio Amplifier PCB Design Tips

I am going to design a stereo audio amplifier with TDA2030A. This is going to be an amplifier that is going to be powered from 27.6V DC and 12W per channel. Is there any sources that I can learn PCB ...
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4answers
2k views

Sub-Miniature version of the 12AU7 valve (vacuum tube)

I want to make my own valve amplifier, and for that, I'll be using an 12AU7 dual triode tube. Since the 12AU7 is quite large, is there a sub-miniature version available? Also: the main difference ...
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1answer
2k views

Capacitor current leakage measurement using transimpedance amplifier

I was reading a text about measuring capacitor's current leakage using a transimpedance amplifier circuit as the author says this is a rather cheap and reliable to measure currnt leakage, I was ...
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4answers
13k views

Intrinsic Gain vs. Voltage Gain

I was wondering what the difference is between intrinsic gain and just "normal" voltage gain of a circuit i.e Vout/Vin?
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2answers
1k views

How can I actuate a relay coil from a headphone jack's internal SPDT?

I want to plug my iPod which in turn supplies power to an external audio amp while sending iPod audio signal to same amp. Is it possible to wire an 1/8" (3.5mm, mini) stereo jack in such a way that ...
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1answer
1k views

Calculating gain of Amplifiers

I have read an interesting formula that says that \$\mbox{Gain of an amplifier} = \dfrac{\mbox{resistance connected at the output}}{\mbox{total resistance between source and gate of the amplifier}}\$...
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1answer
1k views

Video signal attenuation

Which is the best way to attenuate a video signal? I need to reduce the Vpp (Peak-to-Peak Voltage) from 2V of a PAL video signal to 0.75V. I am familiar with filters and amplifiers (like Op-Amp ...
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3answers
2k views

HUGE capacitor recommended in datasheet for Audio Amp

I'm using the TPA3111 audio amplifier in a circuit of mine and I'm working on adding the appropriate capacitors. However, on page 18/19 of the datasheet TI recommends to use a 220mF capacitor on the ...
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3answers
798 views

Part for VHF/FM booster?

I'm needing to create a booster and the easiest schematic I've found is this: http://electronics-diy.com/500mW_FM_VHF_Transmitter_Amplifier_Booster.php however, they do not document what part they use ...
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2answers
4k views

Whatever happened to Tripath?

Tripath made some clever digital amplifier ICs in "class-T" as they called it. Seemed to have a better performance than class-D at a comparable price. Went bankrupt in 2007, but I think this had more ...
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3answers
4k views

Picking a DAC for an audio amplfier

I'm trying to use a specific audio amplifier, TPA3111D1, to power a 10 watt speaker from a microcontroller. I would like to generate sound from a microcontroller that doesn't have a built in DAC, so ...
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2answers
4k views

Input sound to arduino via microphone jack

I'm designing a gadget which will light up LEDs using a microcontroller. I'd like for it to respond to an audio signal, so I was thinking there are a lot of ways I could do it: If I can accurately ...
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1answer
374 views

DAC and/or output amplifier selection for a MP3 player?

I am designing my own MP3 player now. While decoding & all digital backend looks straightforward, I am only puzzled with audio output (i.e. DAC->Amplifier part). My goals are 1: sound quality 2: ...
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3answers
2k views

Analogue automatic gain control

I have to amplify a microphone signal to be in the range -2.5 to +2.5V. It is currently providing a signal that has a peak amplitudes of around 2V. This, however, is highly dependent on the situation (...
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1answer
2k views

Unexpected results with TDA 7052

I built the TDA 7052 circuit from the datasheet and connected it to my computer's sound card and a 50 \$\Omega\$ speaker. Here's the circuit: The \$R_s\$ is the source impedance, which I can't ...
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2answers
1k views

Operation Amplifier with Transistor output

Is there a name for feedback amplifier topologies which include an opamp and transistor in the feed-forward path?. I need to design an amplifier with high bandwidth (almost 100 MHz) and high gain (50) ...
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2answers
185 views

Amplifier power draw

I'm working on a project where I'm going to drive 2 x 8-ohm loudspeakers using 1 (or more) car batteries and a Class-D amplifier. The setup is going to be used at a festival, so I need maximum ...
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4answers
2k views

How to implement SRAM sense amplifier?

I am designing a simple programmable LED screen system as an exercise, and I need a non-standard type of SRAM (16x5) so I am designing the memory circuits. I have looked everywhere (Digikey, TI, ...
2
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1answer
2k views

Can I replace LM358N with NE5532N dual op amp?

In this circuit LM358N 1MHz 32V dual op amp is used (+12V and -12V). The question is, can I simply replace it with NE5532N 10MHz +-22V dual op amp for up to 8MHz DDS signal source? Basically, this ...