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

Debugging ARM Cortex-M0+ HardFaults
Debugging ARM Cortex-M0+ HardFaults
EMP Jammer build
EMP Jammer build
A 3D-printed e-drum pad
A 3D-printed e-drum pad
Interactive geodesic LED dome = extreme geometric fun!
Interactive geodesic LED dome = extreme geometric fun!
Guide to build your 3.3v power supply
Guide to build your 3.3v power supply
SDR radio breathes life into a 75 year old Marconi CR100
SDR radio breathes life into a 75 year old Marconi CR100
A Time for Ranting!
A Time for Ranting!
Emulate a Commodore 64 keyboard with a modern PC and an Arduino
Emulate a Commodore 64 keyboard with a modern PC and an Arduino
USB2005 and USB97C202 Sharing ATA/ATAPI Drive w/ Another Controller
USB2005 and USB97C202 Sharing ATA/ATAPI Drive w/ Another Controller
Robotic Cat Laser
Robotic Cat Laser

Top




Shares