Difference between revisions of "Simple ADCs and DACs"

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m (Earphones / small speakers amps)
 
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====Earphones / small speakers amps====
 
====Earphones / small speakers amps====
Most earphones need only a few milliwatts{{verify}}
 
(depends on their sensitivity, which is sort of their efficiency: dbSPL @ 1mW)
 
  
 +
There's a bunch of ICs that you can use on a line out that can deal with tiny speakers and headphones.
  
Keep in mind that power amps are effectively op amps with larger power stages  
+
Many of these are effectively op amps with larger power stages
: which is why you can one of these amplifiers ''as'' an op amp (except the specs aren't so useful beyond audio)
+
: which is why you can one of these amplifiers ''as'' an audio op amp (the specs aren't so useful beyond audio)
: and why you can build your own from an op amp and e.g. a BJT pair
+
: and why you can build your own from an op amp and a transistor pair
 +
:: ...essentially a simple Class A amplifier.
 +
:: choice of op amp (e.g. TL072) may imply bipolar power, which is impractical unless you happened to have that already.
  
  
* op amp plus and a transistor pair
+
In-ears headphones only need a few milliwatts{{verify}}, while chunkier headphones up to maybe a few hundred milliWatts (depends on their sensitivity, which is sort of their efficiency: dbSPL @ 1mW)
: ...essentially a simple Class A amplifier.
+
: choice of op amp (e.g. TL072) may imply bipolar power, which is impractical unless you happened to have that already.
+
  
 +
 +
 +
Some options:
  
 
* LM386
 
* LM386
: a <1W audio amplifier IC.
+
: an audio amplifier IC -- basically an op amp with a larger output stage
 +
:: Ouput power varies with package, lowest is ~100mW and highest is ~800mW.
 
: 4~12V supply, or 5~18V, depending on package
 
: 4~12V supply, or 5~18V, depending on package
: It's basically an op amp with an output stage
 
 
: gain is 20 (default) up to 200
 
: gain is 20 (default) up to 200
 
: and bypass
 
: and bypass
: Ouput power varies with package, lowest is ~100mW and highest is ~800mW.
 
  
  
 
* LM380
 
* LM380
: 2.5W
+
: similar to LM386, but up to 2.5W
 
: 10~22V supply
 
: 10~22V supply
 +
  
 
* TDA7052
 
* TDA7052

Latest revision as of 02:02, 13 June 2021

The physical and human spects dealing with audio, video, and images

Vision and color perception: objectively describing color · the eyes and the brain · physics, numbers, and (non)linearity · color spaces · references, links, and unsorted stuff

Image: file formats · image processing

Video: format notes · encoding notes · On display speed


Audio physics and physiology: Basic sound physics · Human hearing, psychoacoustics · Descriptions used for sound and music

Digital sound and processing: capture, storage, reproduction · programming and codescs · some glossary · Audio and signal processing - unsorted stuff


Electronic music: Some history, ways of making noises · Gaming synth · Notes on audio latency ··· microphones · studio and stage notes · Effects ·

Music electronics: device voltage and impedance, audio and otherwise · amps and speakers · basic audio hacks · Simple ADCs and DACs · digital audio · multichannel and surround ·

Noise stuff: Stray signals and noise · sound-related noise names · electronic non-coupled noise names · electronic coupled noise · ground loop · strategies to avoid coupled noise · Sampling, reproduction, and transmission distortions · (tape) noise reduction


Unsorted: Visuals DIY · Signal analysis, modeling, processing (some audio, some more generic) · Music fingerprinting and identification

For more, see Category:Audio, video, images

Audio in and out

ADCs

MCP3008, SPI, 8-channel, 10-bit (fewer-channel variants: MCP3004, MCP3002, MCP3001) (EUR1.5)


MCP3208, SPI, 8-channel, 12-bit (fewer-channel variants: MCP3204, MCP3202, MCP3201), (EUR2.5)


ADS1015, I2C, 4-channel 12-Bit ADC (EUR1.0)
ADS1115, I2C, 4-channel 16-Bit ADC (EUR1.5)
(...4 and ...3 variants just have fewer channels)


AD5593, I2C (EUR8)
8 channel, each usable as a 12-bit DAC, 12-bit ADC, or GPIO

The above tends to choose the most-channel variant Note that some of these can be used in differential mode, halving the effective number of channels.

DACs

TLC5620, SPI, 4-channel 8-bit (~EUR3)


MCP4728, I2C, 4-channel 12-bit (EUR0.5)
MCP4725, I2C, 1-channel 12-bit (EUR0.5)
MCP4921, SPI, 1-channel 12-bit (EUR0.5)
MCP4922, SPI, 2-channel 12-bit (EUR1.5)


TDA1543, I2S, 2-channel 16-bit (EUR0.5)
PCM1710, I2S, 2-channel 16-bit (EUR1.5)
DAC8551, , 1-channel 16-bit EUR5 (e.g. in Braids)


DAC08, 8pin, 1-channel 8-bit (EUR0.5)
DAC0800 same idea
TLC5940, 16-channel 12-bit PWM (not DAC) (EUR1.5)


PCM5102, I2S, 2-channel 32-bit


Earphones / small speakers amps

There's a bunch of ICs that you can use on a line out that can deal with tiny speakers and headphones.

Many of these are effectively op amps with larger power stages

which is why you can one of these amplifiers as an audio op amp (the specs aren't so useful beyond audio)
and why you can build your own from an op amp and a transistor pair
...essentially a simple Class A amplifier.
choice of op amp (e.g. TL072) may imply bipolar power, which is impractical unless you happened to have that already.


In-ears headphones only need a few milliwatts(verify), while chunkier headphones up to maybe a few hundred milliWatts (depends on their sensitivity, which is sort of their efficiency: dbSPL @ 1mW)


Some options:

  • LM386
an audio amplifier IC -- basically an op amp with a larger output stage
Ouput power varies with package, lowest is ~100mW and highest is ~800mW.
4~12V supply, or 5~18V, depending on package
gain is 20 (default) up to 200
and bypass


  • LM380
similar to LM386, but up to 2.5W
10~22V supply


  • TDA7052
...or others from that family, like TDA7050
4.5~18V supply
differential output
higher output (~1W)
apparently a little lower noise
from 3V?


  • TDA2822
1.8~15V supply
2* 110mW
gain: 39dB (~90), fixed
two channel


  • PAM8403
Class D (most of the above is class AB)
3~5V supply
3W output
https://electro-dan.co.uk/electronics/pam8403speakers.aspx

Microphone (pre)amp

This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me)

Main jobs:

increase signal level
not introducing noise

A lot of op amps qualify for that.


In practice you have further constraints from

a specific mic's impedance (things are harder if it's higher, like piezos)
a specific mic's sensitivity, typical mic placement
40dB of gain covers a lot of uses
some amount of padding (attenuation) is sometimes also useful
voltage level of what you're driving into expects
use of phantom power
not pick up mains hum (or other EM noise) because increasing any 40dB is probably audible. Probably meaning shielding.


There are a few specific helpful ICs, e.g. with externally tweakable gain, like

  • MAX9814
autogain threshold and attack/release configured via external components
designed somewhat towards electets
and you may not want automatic gain control in various cases.



https://www.homemade-circuits.com/small-amplifier-circuit/




Depending on what you're driving into, some BJTs, or FETs,


Most op-amps (or headphone amps, LM386 seems common in examples) with at least moderate gain, and moderately low noise.


This is more about circuit design.

  • If electret, you want an offset (resistor to high rail) and then probably isolate that from the input with a capacitor
  • switch-mode power is likely to introduce noise, so instead want battery power, or linear regulation,



When you can, put this closer to the mic, though in practice this matters for very quiet mics.


Sensor pre-amps in general can be classified as

current sensitive
charge sensitive
parasitic capacitance


I've seen circuits with LM386, LM358,


https://www.homemade-circuits.com/small-amplifier-circuit/

http://www.thatcorp.com/datashts/AES129_Designing_Mic_Preamps.pdf

Combinations

DAC and amp

MAX98357, I2S, 1-channel, 3W


ADC, DAC, and amp

WM8731, I2S, 2 ADC, 2 DAC