digital voice recorder

[piyush_it1]

my project includes sampling the voice using ADC and storing the data in flash memory and finally retreiving it from memory using DAC. The platform being 89c51 microcontroller

1.) i've made a basic preamplifier and checked it's o/p on CRO and it's amplitude is limited to 1V. I want to know whether my ADC could sample such variations.

2.) Please tell me some power amplifier configuration
(if possibly LM 386)to test the o/p of this circuit , by connecting it at o/p of this circuit,without connecting it to microcontroller.


thanks

 

[piyush_it1]

schematic

my circuit is not attached as attachment. Kindly help.[/img]

 

[akg]

1.) i've made a basic preamplifier and checked it's o/p on CRO and it's amplitude is limited to 1V. I want to know whether my ADC could sample such variations.

most of the ADC i/p varies from 0-5V for FSD , so u have to amplify the signal 5 times to get the full resolution of the adc.

2.) Please tell me some power amplifier configuration
(if possibly LM 386)to test the o/p of this circuit , by connecting it at o/p of this circuit,without connecting it to microcontroller.

u can find sample design of poweramp in the datasheet of lm386

 

[Nigel Goodwin]

A couple of points for digitising audio:

1) You MUST have a low pass filter on the input, with a fairly sharp cutoff no higher than half the sampling rate, and preferably lower than than.

2) You MUST make 100% sure that you NEVER clip the input to the DAC, this produces incredibly bad distortion

 

[akg]

A couple of points for digitising audio:

1) You MUST have a low pass filter on the input, with a fairly sharp cutoff no higher than half the sampling rate, and preferably lower than than.

2) You MUST make 100% sure that you NEVER clip the input to the DAC, this produces incredibly bad distortion

ADC ??

 

[Nigel Goodwin]

A couple of points for digitising audio:

1) You MUST have a low pass filter on the input, with a fairly sharp cutoff no higher than half the sampling rate, and preferably lower than than.

2) You MUST make 100% sure that you NEVER clip the input to the DAC, this produces incredibly bad distortion

ADC ??

Yes! - sorry