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)
2
votes
1answer
969 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?
thanks
1
vote
2answers
393 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 ...
1
vote
1answer
352 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 ...
0
votes
1answer
333 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 ...
4
votes
3answers
572 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 ...
2
votes
3answers
393 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 ...
2
votes
1answer
737 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 ...
2
votes
3answers
653 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 ...
2
votes
2answers
2k 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 ...
3
votes
1answer
234 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: ...
3
votes
3answers
546 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 ...
1
vote
1answer
743 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 ...
1
vote
2answers
659 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) ...
2
votes
2answers
110 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 ...
1
vote
4answers
869 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, ...
1
vote
1answer
560 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 ...
2
votes
3answers
434 views
Solving DC Operating Point of Common Source Amp
My lab partner and I are really stumped. We are given a circuit that has a FET with a \$V_{DD} = -V_{SS} = 15\mbox{ }V\$. We are told \$A_V = 20\$ and \$I_{DS} = 1\mbox{ }mA\$. The DC circuit is ...
3
votes
1answer
147 views
How can I protect the amplifier behind a headphone jack when interfacing with external circuitry?
I am wanting to mess with the output of my guitar amp. Not actually opening it up, just taking the headphone-output and connecting it to a breadboard and such.
What form of protection, if any, ...
8
votes
3answers
498 views
Simple Adaptive Amplifier Options for Sensor Interfaces
Related: High Resolution ADC for Noisy Sensors in Variable Conditions
I'm building an interface using resistive textile-based sensors that may have different resistance ranges depending on ...
14
votes
5answers
3k 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 ...
4
votes
2answers
1k views
Amplifying sound from a microphone
I have a small piezoelectric ultrasonic microphone (receiving signals of around 40 kHz). But the voltages it generates are too small to be read by my micro-controller's ADC. So I want to amplify the ...
1
vote
2answers
1k views
Short circuit protecting a class AB amplifier
I am designing a little class AB amplifier for a small circuit. This circuit is biased such that it has low crossover distortion. Below is a schematic:
As you can see, I have inserted 68 ohm ...
3
votes
1answer
575 views
Testing an Audio Power Amp with Paralleled Transistors
A question concerning my current repair project of an audio amp that uses big (600 W) but otherwise rather classic complementary output stages:
I assume when testing an audio power amp with 6 pairs ...
5
votes
2answers
534 views
Choosing output filter inductors for switching power amplifiers
Class D PWM switching power amplifiers use an LC filter at the output to filter out the switching harmonics:
Other than the inductance value, what properties are important for this inductor? What ...
1
vote
2answers
167 views
Does socket orientation have an effect on sound?
Is it possible that the socket orientation (in Europe: one pin 230V, the other ground) can have an effect (albeit very small) on the amplifier behavior of a very old stereo sound system? What is, if ...
1
vote
2answers
419 views
Smallest audio amplifier?
At the moment I'm using an amplifier based around a NPN transistor and some resistors. Its configuration is as an emitter follower. Pin 25 supplies internal audio from a DAC on the chip.
See this ...
5
votes
4answers
627 views
building an audio amplifier for 2.5 ohm speakers
I recently dug out of my box o' stuff a pair of seemingly decent 2.5ohm bookshelf speakers. I wired them to an old mp3 player I have and while they sound good at low volumes, I get lots of distortion ...
2
votes
1answer
176 views
What should I be using to amplify a heat flux and load cell signal?
For my senior design project, we have various sensors (Thermocouples, Heat flux sensors, load cell) plugged into our DAQ. We are using LabView and some National Instruments devices (ugh) and ...
4
votes
5answers
378 views
Troubleshooting a broken speaker system
First I apologize if this is the wrong place for this question.
Recently my sub-woofer/amplifier stopped working, and I would like to know what is broken. I opened the case and didn't find any ...
3
votes
2answers
656 views
Piggy-backing off power amplifier outputs
My motor-scooter has a built in radio, with a small speak either side of the front panel, below the handlebars. It's a JonWay, i.e. cheap Chinese, so I suspect the radio is more suited to developing ...
13
votes
3answers
2k views
I don't quite understand this FET-BJT preamp circuit
I see this circuit a lot on electret microphone preamps, but I don't quite understand it. The FET is operated as a common source amplifier, so it has gain, inverts, and has relatively high output ...
7
votes
8answers
592 views
Does a radio station main amplifier work at the speed of light?
I'm having an argument with a classmate and we can't agree.
He tells me that it's not possible for the amplifier of a radio station to amplify the input signal "instantaneously" (at the speed of ...
5
votes
3answers
2k views
Why the resistor in this op-amp circuit?
Here's a circuit diagram for a signal response test circuit from the spec sheet for a HA-5195 op amp and looks like a non-inverting amplifier circuit with a gain of 5, plus the 200Ω resistor between ...
