Questions tagged [audio]

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

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5
votes
3answers
9k views

Ground loop? Switch mode power supply noise

I have a single 12V supply powering a 12V class D audio amplifier (Tripath TA2020 based, model 'SMSL SA-36') (C) and a very cheap 12V to 5V 2A rated switch mode converter (A). The 5V is used to power ...
8
votes
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 ...
1
vote
2answers
2k views

Can I replace MC33204P with one of these other op amps?

I'm working to make this schematic and I was wondering if it is possible to swap out the MC33204p with either LM348N or LM339AN. And if you could let me know why swapping them would still work I'd be ...
1
vote
2answers
2k views

How can I best amplify a signal from my headphone jack to operate a relay 3-32VDC?

I'm working with the following op-amps: LM308AN LM358P UA741CP I want to make a small box that will control the power to any string of christmas lights based off of music that is playing. I would ...
4
votes
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 ...
6
votes
7answers
3k views

Multi-channel bar graph LED drivers

I want to build a circuit that shows the real-time frequency components of an audio signal on a number of bar graphs of some sort. Currently, my plan is to build 12 band-pass op-amp filters, and then ...
3
votes
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 ...
1
vote
1answer
5k views

How does square's device send 3 tracks from the credit card trough a single audio channel at once?

There are 3 tracks on a credit card. A 3 track reader would need 3 channels to send the audio to the phone for processing. Does iPhone allow the app to turn the other 2 stereo outputs into input ...
1
vote
2answers
327 views

Video entry sender has only one signal line for Microphone + Speaker

I am planning on connecting an off-the-shelf door camera (audio/video sender) to my project. I've posted an extract from their manual here The video output is composite which I can support, but ...
3
votes
4answers
247 views

Combining an Audio Signal and 9 VDC on the same Trace

I have a backplane where 4 individual modules plug into it and provide various sound effects. To control which module is powered and to route the input signal to it, there is a 2-pole, 5-way ...
14
votes
12answers
11k views

Polyphonic sounds from a microcontroller?

I can make monophonic sounds by toggling a single pin (at a varying rate) connected to a piezo buzzer. How can I generate two mixed audio signals in software to create polyphony? Here's the code I'm ...
3
votes
1answer
3k views

What is a 3-pole cable?

This may seem a little dumbfounded but I asked someone if it was safe to use a 2.5mm - 3.5mm cable converter on both ends of a male 3.5mm cable, and they told me it was alright as long as it was a 3-...
3
votes
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: ...
3
votes
2answers
293 views

Connector Choice for Arduino/MIDI Bridging Interface

I'm in the early stages of planning a MIDI-mapping component that I can plug into my Alesis DM-6 drum kit so I can ultimately play it through Rock Band 3. I know there are commercial options out there,...
2
votes
2answers
175 views

How Would I Nomalize Cable TV Volume Between Commercials and Programming

I have had it with commercials on cable TV being a lot louder than the program I happen to be watching. I have also had the reverse where the program switches scenes and you cannot make out what the ...
1
vote
3answers
432 views

iPod connector car control

I recently bought a car with an iPod dock. When I plug in the iPod disables and I am forced to control it with the car's audio controls. I want to get around this. Can I simply yank pin 21 from an ...
1
vote
1answer
297 views

Modulation of 36 MHz wireless microphones

I've been given a handful of wireless microphones that transmit in the 36 MHz band, but unfortunately no receiver was included and proper receivers for that wireless mikes seem to be crazy-expensive. ...
3
votes
4answers
3k views

audio controlled relay circuit

I need a circuit that fires a relay when it detects audio pulses from one channel of an mp3 player. I'm going to record audio pulses in sync with the music to control a motor for mouth movement. Its ...
3
votes
2answers
1k views

Why do speakers sound different when they're not fully plugged in?

I've noticed that if there's not a good connection between my jack and the port, like if it's dirty or half plugged in, then the sound is different, but there is still sound, and sometimes twisting it ...
2
votes
2answers
1k views

Balancing Unbalanced Audio Inputs

I'm wanting to nicely balance some unbalanced inputs to a power amp for good CMRR, and because I'm feeling too lazy to start trying to closely match pairs of resistors, I'm looking at using a hi-fi ...
1
vote
1answer
1k views

Schematic for 4-band stereo equalizer?

I wand to make a simple stereo 4-band EQ for a mid-fi amp I'm building. I draw my knowledge from this excellent article - however, it only seems to talk about peak/notch bands and not low and high ...
1
vote
1answer
3k views

Using the AC97 Codec on an Atlys Spartan 6 Board

I'm a beginner to FPGA programming. I just started programming an Atlys Spartan 6 board and so far have written one program to blink LEDs in a counter pattern. Now I'm trying to send the clock signal ...
5
votes
1answer
2k 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 ...
0
votes
2answers
334 views

troubleshooting GEOFEX guitar effect panner

I'm building a circuit that allows me to blend a guitar effect in and out, based on >this< (page 2, bottom circuit). I have, however, replaced the 10k pot and the 15k and 51k resistors with 100k, ...
3
votes
1answer
216 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, ...
4
votes
2answers
2k views

Crosspoint switch matrix for audio frequency signal?

Modular synths have recently piqued my interest, but patch cords are hell. I have been thinking of some intelligent way to route signals - something microcontroller-driven and remembering different ...
5
votes
6answers
2k views

Preventing audio signal saturation

I am trying to implement an algorithm on audio signals. The algo operates on the signal on a frame-by-frame basis. One of the intermediate stages requires addition of the signal to the previous frames....
3
votes
1answer
2k views

Which PIC MCU for an Audio player?

DESCRIPTION: It will play .wav and .mp3 files from a Micro SD Card. The memory card can be written through USB (its an in-board unit). It will have a LCD screen to show the contents and functions ...
0
votes
2answers
3k views

Roland Microcube guitar amp damaged beyond repair?

My power regulated ac/dc adapter broke the other day and my friend thought it was a good idea to cut the wire from the mains adapter, trim the ends and plug this directly into the mains. he then ...
1
vote
1answer
616 views

Roland Microcube modification, need a hand

My Roland cube has stopped working, the guitar input connector for the main channel has been faulty for a while but now its gone completely. I opened it up and it looks like the connector is badly ...
7
votes
2answers
2k views

Tiny, cheap audio buffer with mute?

I need to buffer an audio signal (feeding into a variable input impedance), and make it mutable with a digital control. The best thing I can think of is an op-amp (maybe TS971? 3×2 mm SOT23) feeding ...
3
votes
5answers
2k views

How to sample audio at Nyquist frequency with MSP430F5438?

I want to: Input an analog audio track Using the microcontroller ADC, convert it to a digital output Then have the microcontollers/boards timer sample the data at selected intervals Resample the "...
1
vote
2answers
180 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 ...
6
votes
3answers
2k views

Cheapest reverb to stick in analog audio circuitry?

What are the cheapest (<$5 in large quantities) reverb implementations you can think of for interfacing with analog audio circuitry? It can be crappy but, of course, better is better.
2
votes
1answer
7k views

Question About the Ground Wire on Aux Attachment Circuit for my Car

This is a specific question about a specific circuit, but I'm trying to use it as a learning experience as I'm still new to electronics and need to take practical knowledge where I can get it. I ...
5
votes
3answers
9k views

How to read an audio signal using ATMega328?

I was trying to use the ATMega328 ADC port A0 to read a signal. The hardware I used was: Seeeduino Stalker Electronic Brick Shield Microphone Electronic Brick (I found a link to the original ...
3
votes
2answers
1k views

Line level audio and muxing

I am developing an OSD project which also manipulates audio signals. The aim is to add a 'mux' system, which allows a microcontroller to select between the input audio and an internally generated ...
4
votes
3answers
2k views

My Atmega328 seems to be overkill, what should I use instead?

I'm using an Atmega328 chip with the arduino bootloader in a very small circuit. The sketch simply plays a tune using the tone() function to play a melody through a piezo speaker on a single pin. ...
3
votes
4answers
3k views

Controlling DC (Pager) Motor with Audio Signal

I'm trying to control a DC (pager) motor with a sound signal so that I can use an audio synthesizer to control the speed of the motor. I'm hoping to modulate the speed of the motor at audio rate (1-...
4
votes
3answers
2k views

Audio Frequency Shift Keying to Arduino

I am attempting to have an Arduino interpret an AFSK signal, this is very vague but can anyone just point me in the right direction for detecting the frequency of the AFSK signal with an arduino?
6
votes
2answers
4k views

Why is it ok to use polarized caps to remove DC offset from an audio input?

I've seen circuit diagrams that use a polarize electrolytic to remove DC offsets from an input audio signal. The cap is polarized. Why is this ok?