Friday, April 22, 2011

Voice Record and Playback Circuit Using IC ISD1020A

This voice or sound recorder/playback built with IC ISD1012, ISD1016 and ISD1020 which are produced by ISD and allow sound voice recording and play-back. The last 2 digits show the maximum legth of recording time in seconds. this chip has many features like automatic gain control, anti aliasing filter, built in audio amplifier and smoothing filter. The IC is fully compatible to microprocessors and can be used for a myriad of applications. The voice is stored in their natural form in the non-volatile memory cells inside the IC which enables a high quality reproduction. T

Voice Record and Playback Circuit Using IC ISD1020A
Voice Record and Playback Circuit Using IC ISD1020A

The circuit is designed as per the application diagram in the datasheet. Pin23(CE) is the chip enable pin and it has to be held low using switch in order to perform a record or playback cycle. Pin 27 (P/R) is the playback/record pin and a high level on it selects a playback cycle while a low level on it selects a record cycle. The selection can be done using the switch S3.The pin 24 (PD) is the power down pin. It has to be held high using switch S2 in order to pull the device to a extremely low power mode while there is no recording or playback (idle state).The resistor R1 and capacitor C1 determines the release time of the internal AGC circuit. The resistor R5 and capacitor C5 connected across the pin 20 and pin 21 provides an additional cut-off to the low frequency end of the voice pass band.

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