Questions about designing electronics for measuring, processing, and amplifying audio signals.

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2
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0answers
26 views

How can I find and remove servo/motor noise from this audio amplifier?

I am troubleshooting an audio noise problem in project which has several components wired together as follows: Overview: The overall project does some motion control with a servo and has an audio ...
1
vote
1answer
21 views

Class D inductor current calculation

How do I calculate the required inductor current (RMS, saturation) for a class D amplifier? Assuming the following configuration: Speaker impedance (Z) = 4 ohms Power output (P) = 400W ...
1
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0answers
36 views

Electret Mic Circuit Using JFET Bootstrap

I thought this circuit was clever so I'm sharing: The JFET current source is bootstrapping the electret and thereby providing 20dB of linearized gain. The bootstapping network also provides for ...
0
votes
2answers
102 views

What is this connector?

I'm working on soldering a 3.5 mm female jack to the Thinkgeek Personal Soundtrack Shirt Controller so I can output to any speaker I please, however I am wondering if this is an actual connector I can ...
1
vote
0answers
36 views

Routing Audio Ground - needed or not?

I'm trying to build a guitar pedal switcher (efectively a box that provides multiple effect loops that can be independently bypassed from a single microprocessor) and while building a working ...
3
votes
2answers
80 views

Quiet inductors?

Are certain types of inductors more likely to create an audible sound than others when under use? Is there any sort of best-practice or guideline to minimize such humming or buzzing sounds? I.E. ...
1
vote
0answers
30 views

Linear vs. Audio Taper for RC Network

I'm building a distortion pedal and I was wondering which tapers to use for which potentiometers in the tone control section. I normally design my own circuits, but I'm going by someone else's ...
1
vote
2answers
93 views

Raspberry Pi + Microcontroller for commuting audio input and output (audio matrix switch) [closed]

I am new in electronics and I'm working on a personal project with Raspberry Pi that I need help. I want to make a board that allows to commute 4 audio inputs (TV, MP3, DVD, FM web) in 4 audio ...
1
vote
1answer
39 views

PDM to PCM conversion workload on 32-bit micro (such as STM32)

Can anyone provide a rough estimate of the processing power required to do PDM (e.g. audio from MEMS microphone) to PCM conversion on a 32-bit microcontroller ? Specifically - I see ST provides a PDM ...
2
votes
3answers
64 views

Playing sounds on an AVR MCU [closed]

I never had to deal with sound and I am pretty sure some of you guys have some experience in that kind of application. My question is more about getting some tips on the different ways to implement ...
0
votes
1answer
77 views

How to eliminate early effect in constant current source

When designing an differential amplifier it is important to have a precise constant current source (which I will abbreviate with CCS). It helps to keep out signal injections from the supply rails. A ...
3
votes
3answers
300 views

Sending audio over infrared?

I am an undergraduate and new to electronics. I wanted to know if it is possible to send audio over an infrared LED? I plan to use a 555 timer to generate PWM output with carrier at around 44 Khz to ...
1
vote
1answer
54 views

Headphone jack connection: is this setup safe? [closed]

Is this setup safe for the equipment? And am I going to be able to hear both of the sources?
1
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1answer
37 views

Colpitts VCO by varying base voltage

I've noticed that if I build a Colpitts oscillator (audio range) using a transistor in the common base configuration (similar to the circuit here) I can vary the voltage on the base and get a wide ...
0
votes
2answers
74 views

Does the VU meter on audio amplifiers measure the input or output level?

Does the VU meter on commercial audio amplifiers measure the level of the input signal or the level of the amplified signal?
0
votes
1answer
39 views

Audio bluetooth board. RX and TX?

Looking at a usb bluetooth audio aux device board I saw RX and TX. What are these points for?
0
votes
1answer
47 views

I2S based Codec

I want to drive a small mono-speaker that helps in announcing few messages. I am just learning and doing it now. My board is based on I.MX6, I am interfacing it to a an audio codec TLV320AIC32 via ...
4
votes
1answer
167 views

Headphone output: DC Bias?

Need some electrical advice, as my days of my Electrical Engineering degree are well behind me... I have 4 PMR446 radios ("walkie-talkies"). They work great, but when using an earpiece, every-time ...
0
votes
1answer
69 views

Microchip PIC32 MEB Audio Recording

Well, I was just wondering, I have been using the Microchip PIC32 USB Starter Kit with the MEB (Multimedia Expantion Board 1) for some projects. One of them is to record audio and analyse it, the ...
0
votes
1answer
44 views

Amplifying analogue audio from an iPhone docking station

So I have an old iPhone speaker dock that broke after I plugged in the wrong cable and fried the microchips on the circuit board. From it however I salvaged the dock connector itself and a couple ...
0
votes
1answer
56 views

Solid State Relay Capacitance Bad for Audio?

Regarding MOSFET optocoupler relays like the Panasonic AQW212, am I correct in understanding that the capcitance between the terminals and ground when the switch is open ("off") is around 100pF when ...
0
votes
0answers
33 views

Bypass switch for amp

I've just successfully completed a CMOY amp and I'm pleased with the result. However, I want to be able to hear the difference between the original signal and the amplified signal, so I put a switch ...
1
vote
1answer
50 views

Get peak voltage from RMS power (Audio amplifier)

I want to calculate the peak voltage output of an audio amplifier when driving at its maximum rated power, a loudspeaker. For example, an amplifier rated at 50W RMS into 8 ohms, driving an 8 ohm ...
0
votes
1answer
37 views

How can use MP45DT02 and CS43L22 DAC with STM32F4?

I'm doing an application with MP45DT02 MEMS audio sensor omnidirectional digital microphone. I'd like to use a STM32F4 MCU to control it, but I don't know much about it. Can I take input from the ...
0
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0answers
56 views

Why does this State-Variable low pass filter overheat when turning up resonance?

I am trying to build an audio-frequency state-variable resonant filter. Power supply is ±15V. The circuit contains three TL072 op-amps and three LM13700 OTAs. It receives audio input from -2.5V to ...
0
votes
3answers
148 views

Amplifier design: feedback with unclear poles

When designing a closed loop amplifier for audio the poles of the open-loop transfer function are usually only vaguely known. \$\frac{1}{(s-p_1)(s-p_2)...}\$ These poles can be modeled as \$RC\$ ...
0
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0answers
82 views

Can this op amp circuit easily be modified to provide differential input?

I have a "noisy ground" problem which seems to be essentially the same as the one described in this old post: Ground loop? Switch mode power supply noise The solution (as provided in the answers to ...
0
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0answers
66 views

USB Audio Stream to Codec

I have been trying to design a USB Audio Interface with an Atmel SAM3U microcontroller and I think I have hit a wall in my thinking process. As a sidenote, I'm relatively new to the world of ...
0
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1answer
118 views

What kind of device is this? [closed]

Hi, I found this device lying around somewhere and I have no idea what it is. Can someone help me figure out what it is?
0
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0answers
81 views

One-shot sound button/trigger for Arduino Sound Player

I've succeeded in making a simple Arduino ATMega328 sound player on my breadboard following this guide. . . http://highlowtech.org/?p=1963 http://playground.arduino.cc/Code/PCMAudio But, here's my ...
0
votes
1answer
56 views

Why is the cut summed in a graphic equalizer?

I would think a basic graphic equalizer could function as such: a bank of filters, each with their own connection through a potentiometer to a summer (such as an op-amp summer). However, I've run ...
1
vote
2answers
114 views

What is the audio voltage of an android phone?

For a project I am currently working on, I need to use the audio output of an android device. Is there a standard max voltage?
1
vote
2answers
62 views

Looking for OP-Amp with good rail to rail performance, 5V to 0V [closed]

There are thousands of OP-Amps on Farnell's website, so I thought asking the stack-exchange community might be a good idea. I am looking for an OP-Amp for use in my project. I currently have an ...
1
vote
0answers
20 views

CS42L52 output PCM?

I have an MCU connected to a CS42L52 codec over I2S and am able to input and output sound with no problems. When I pass the input from the codec, through the MCU, and back to the codec for output, ...
0
votes
2answers
72 views

Ferrite Bead Current Rating

Could anyone let me know how can I calculate the current rating required for a ferrite bead on speaker path? The speaker impedance is 32 ohms.
3
votes
3answers
71 views

How to correctly connect audio plug to LM386?

I'm working on my first circuit which includes LM386 chip and some music. Since I don't have a lot of experience with electronics I need a little help with audio plug. It's the same as that: I know ...
0
votes
0answers
23 views

Audio streaming issue with CSR-8670 kit

We are using Source App in "Analogue mode" in which we reached to a point where our kit is able to paired with the mobile device but when we start to play audio in mobile through paired CSR audio ...
2
votes
1answer
58 views

Integrated audio DSP with free tools?

(Intro here, you can skip this for the actual question) As a hobby project I'm building an audio amplifier. It'll be the amp for my "home theater". I only have a small room so there's no room for 5.1 ...
-1
votes
1answer
50 views

Static in earphones when scrolling with mouse [closed]

Why do I sometimes hear faint static in my headphones when I scroll with my mouse? I have noticed this on multiple(4) computers, with Windows 7 and 8. Does anybody else notice this? It happens when I ...
2
votes
2answers
79 views

QAM's Demodulation

Let me confirm how the demodulation process of QAM is. $$s(t)=I(t)sin(2πft)+Q(t)cos(2πft)$$ Then we have to guess \$I(t)\$ and \$Q(t)\$ in order to know what the said bit formation of the ...
3
votes
2answers
206 views

How can I simulate a bridged output of a speaker at 8 ohms?

Following on from my previous post on a single 5V rail amplifier, I'm trying to simulate a bridged output op amp set up to drive an 8 0hm load. One of the solutions was: Use a bridge output. This ...
1
vote
2answers
121 views

What is the low frequency limit for ferrite cores in audio applications?

I've searched high and low through the ferrite magnetics catalogs and this list for an answer and can't find data on ferrite core permeability below 10kHz. My application is for audio use and I need ...
1
vote
3answers
285 views

Alternative to LM386? To drive 8 ohm speaker with 9V circuit

I am getting pretty tired of debugging the LM386 integration into my project! I'm building a drum machine, based around schmnitt trigger oscilators and a white noise generator. I'd post the complete ...
1
vote
4answers
738 views

Is the only way to drive a speaker with a positive and negative rail?

I want to create a simple sinusoidal oscillator (Wien-bridge with soft limiting), connected to a high gain amplifier. I don't have much experience with audio, but I'm guessing a speaker needs a ...
2
votes
1answer
83 views

What is the use of dual differential amplifiers in audio applications?

Why do audio amplifiers use dual differential pairs sometimes? Is there a mathematical justification and not just "the joy of symmetry"? Any hints, especially with some math would be of great help. ...
2
votes
1answer
132 views

Why are audio power supplies center negative?

I see that power supplies for guitar pedals, speakers, etc are always center negative. Is this a conscious design choice, or is it a marketing trap?
1
vote
1answer
133 views

Use “real” condenser microphone element instead of electret condenser microphone

Apologies my original question was completely unhelpful, I'm trying to make a USB condenser microphone, and the tutorial I was trying to follow used two electret condenser microphones, which were ...
0
votes
0answers
43 views

Preamp circuit LED driver

I was wondering if the this schematic would work in my scenario: My scenario is that I want to play an audio file from my phone, in which the audio file will be played from my phone which will be ...
0
votes
1answer
51 views

Audio Precision SNR

I recently checked SNR of the class D Amplifier on board our product. I used AP2722 for amplifier characterization. The SNR displayed by the analyzer as below: -87.85 db below 2.76 dbV reference ...
0
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2answers
49 views

Optimal headphone impedance

Looking at the data sheet of the MAX4410 headphone driver, lower impedance headphones will get more power. Is this true in general for laptop headphone drivers? especially with regards to 8-32 ohm ...