Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Digital Voice Recorder

Digital Voice Recorder

It is a simple device that emulates a dictaphone, and stores the voice digitally. The Analog circuitry in this project contains a microphone pre-amplifier, an anti-aliasing filter, a postfilter and a power-amplifier.
The heart of the Digital Voice Recorder (DVR) is an Atmel AT90S8535 microcontroller. It is a powerful RISC 8-bit microcontroller, with 8kB internal FLASH program memory, 512 bytes EEPROM and 512 bytes of SRAM. It’s RISC CPU core can execute almost 1 instruction per cycle. The core is complemented with a rich set of peripherals, including I/O ports, timers, PWM, A/D converters, etc. Details can be found at Atmel’s Website.

A 16 Megabit data-storage FLASH chip (AT45D161) is attached to the MCU through a serial interface (SPI). This stores the sampled data from the MCU, and also sends back stored data to the MCU. Four pushbutton switches and four LEDs form the user interface. These are connected to the MCU’s I/O ports. The audio is picked up by a condenser microphone, and amplified by an op-amp based amplifier. It is filtered and passed to the MCU’s A/D converter, which samples the audio at a rate of 8kHz. The 10-bit samples are scaled down to 8 bits before storage. During playback, the samples stored in the FLASH chip are sent to the MCU’s PWM module, which produces a 15kHz PWM signal whose pulsewidth is proportional to the amplitude of the sample. This is filtered and amplified, and is passed to a loudspeaker.

Visit Here for more.







 

More Articles to Read

Gesture Controlled Smart Home
Gesture Controlled Smart Home
Design for a Wideband, Differential Transimpedance DAC Output
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Bertan/Spellman 225-20R HV power supply teardown
Blinking Christmas Lights
Blinking Christmas Lights
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adding an “extra sense” with rangefinders
Adding an “extra sense” with rangefinders
This wireless game controller looks like a rug
This wireless game controller looks like a rug
How to run your ESP8266 for years on a battery
How to run your ESP8266 for years on a battery
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Making beats on a tiny Arduino DJ controller
Making beats on a tiny Arduino DJ controller
Qinsi-QS5100 Sn63Pb37 solder profile
Qinsi-QS5100 Sn63Pb37 solder profile
Water Detection System
Water Detection System
Professional Hi-Fi 15W Tube Amplifier circuit
Professional Hi-Fi 15W Tube Amplifier circuit
This Arduino machine will judge how sick your ollies are
This Arduino machine will judge how sick your ollies are
Turn an old payphone into a boombox for ’90s hits
Turn an old payphone into a boombox for ’90s hits
Big F’n 3D printer build
Big F’n 3D printer build
Temperature alarm for boiling milk
Temperature alarm for boiling milk
QuadBot is a 3D-printable walking robot for everyone
QuadBot is a 3D-printable walking robot for everyone
MicroConverter I2C Compatible Interface
MicroConverter I2C Compatible Interface

Top


Shares