Viktor made a sound trigger for his DSLR camera:
Now that I can take pictures of lightning I decided that I also want to be able to trigger my camera with sound.
An op-amp filters and amplifies a microphone signal. The output is fed to a PIC microcontroller that triggers the flash when the sound reaches a certain level. The trigger sound level and shutter delay are set with a pot. [via]
Lil Bang – Sound trigger for cameras - [Link]
This circuit is a digital sound level meter with a LCD screen, capable of displaying 80 characters (4 rows with 20 characters on each). You can build this LCD display. It also provides more debugging information, such as the minimum and maximum analog-to-digital samples that were measured during each period. [via]
Digital Sound Level Meter - [Link]
This project makes a PIC microcontroller speak audio PCM sounds using PWM modulation! Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code . Pulse-width modulation (PWM) of a signal or power source involves the modulation of its duty cycle, to either convey information over a communications channel or control the amount of power sent to a load .
PIC sound player (PCM to PWM converter) - [Link]
Here is a Sound Localization Sensor that I made. I searched for days trying to find a commercial sound localization sensor or info on how to build one. Sound localization is what the human ear does when it determines that a sound is coming from the left or right. After talking to some gentlemen over at the Arduino forums, I realized that it wasn’t going to be as simple as I thought.
DIY Sound Localization Sensor – [Link]
Generating sound waves from PC sound card isn’t new ting. You can even download tons of software that allows generating various waves like sine, square, triangle waves on speaker output. Such sound generator gives quite good results that are acceptable in most situations like testing audio equipment or feeding complex signals in to your projects.
Generating complex sound waves on PC – [Link]
The Daisy is a multipurpose sound player for embedded applications. It can be used as a standalone personal music player,as the sound for an art project, in a kiosk, as a museum tour guide, in a toy, or anywhere that high quality embedded audio is desired. It uses MMC or SD flash memory cards so storage size is unlimited. It has several interface modes for either human or machine control.
The Daisy is based on the Microchip PIC18F45j10, which is a new family of PIC microcontrollers. They are capable of running at a full 40MHz at 3.3 volts, which makes them ideal for this application. Also, most of the pins are 5 volt tolerant, easing interface with other microcontrollers. The other chip on board is a VS1011 from VLSI, Finland. It is an .mp3 and .wav decoder chip, a DAC, and a headphone amplifier all in one 28 pin package. I’ve been fooling around with this family of decoders since 2001 and I have never found an mp3 file it couldn’t decode… and the sound is very good!
Daisy mp3 project – [Link]
Make a sound card is no more a complex issue. If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card. This sound card can be powered from USB port and has one stereo output. You don’t need to install any driver for Windows XP and Vista, because they are already inside. This is really plug and play.
USB Sound Card with PCM2702 - [Link]
This project devised by two Cornell students in 2003,they wrote: For this endeavour, we first built an input stage that will amplify the input signal, as well as bias it to 2.5V (since the ADC can only sample positive signals). The ADC (MAX1111) is controlled by the microprocessor (Mega 32) using the SPI interface which was much easier than manually configuring a port to interface with the ADC(believe me, we tried that). We set the Mega 32 to sample the input at about 12 KHz which is fast enough to meet the Nyquist requirement for analog to digital sampling. The digital effects were done using by manipulating the input (which will be discussed in the Design page) and the output is passed to a R-2R DAC to a output amplifier stage and finally, to the speaker. [via]
AVR Sound Effects Processor - [Link]
This is a very simple project demonstrating microcontroller sound generating. It plays audio bit stream generated from MIDI files. MIDI files must be converted with special Perl program (MIDICSV).
Project is made of only three parts: piezo buzzer, power supply (3×15V AA batteries) and AVR Tamega16 microcontroller. MCU runs from internal 1MHz clock – so no external clock sources are needed. It can be easily built quickly on any breadboard. Code is written in AVR-GCC language and can be compiled with WinAVR tools. [via]
Entry level AVR sound player - [Link]
The PeanutBot robot consists of three microphone circuits, three servo motors, an MCU and a PC. The three microphones were used to triangulate the angle of the source relative to the robot. The audio source plays a continuous stream of pulses. Pulses were chosen over a continuous tone because, instead of detecting phase difference in the audio signal, our system detects the arrival time of the signal at a certain amplitude at each microphone.
Autonomous Sound Finding Robot - [Link]