Light operated voice messenger

This is a simple electronic project which we implemented for some local event to guide audience automatically with some prerecorded voice messages. The core component of this unit is ISD1820PY voice record/playback chip which is manufactured by Nuvoton Technologies. Except for ISD1820PY, this unit use commonly available low power LASER and LDR assembly to detect people. To drive the loudspeaker we use popular LM386 audio power amplifier.

Thanks to ISD1820PY and LM386 this system can be implemented on a breadboard or on stripboard with a minimum number of external components. This circuit is designed to drive using 6V or 9V DC battery but it can also drive with 6V or 9V DC regulated power supply. To get 3.3V we use an LD1117V33 voltage regulator, but this can also be replaced with some commonly available 3.3V regulators such as LD33V, MC33269-3.3, etc. For the speaker, we use 4-inch 8Ω full-range speaker.

A prototype version of electronic voice messenger.

This unit can be used with both dynamic and condenser microphones but according to our experiments, ISD1820PY produces excellent results with dynamic microphones. As per our observation with some condenser microphones, results are not up to the satisfactory level.

A detailed schematic of this project is available to download at google drive.

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