Voice Modulator (Sound Effects – Funny Sound)

Rajkumar Sharma      http://www.rajkumarsharma.com  
8339

VOICE_MODULATOR

Voice Modulator project is designed around HT8950A to provide two special sound effects viz. Vibrato & Robot.

Description

This project  provides two special effects: vibrato and robot. The vibrato effect is generated by alternating the frequency of an input signal up and down at a rate of 8Hz. The robot function, on the other hand, converts an input voice into a robot voice. Both effects can be selected depending on which pin is triggered, either ROB or VIB. For the output frequency level shifting, the chips provide seven steps which can be selected from the two groups of pins namely, SW0, SW1 and SW2 for electronic direct selection and ROB, TGD, TGU and VIB for push button selection.

The HT8950 include a built-in microphone amplifier with an internal bias, an 8-bit A/D converter, a built-in SRAM as well as a current output type 8-bit D/A converter. The 8-bit A/D and D/A converters with a sampling rate of 8kHz ensures a high quality and high S/N ratio output voice. The chips provide an LED indicator which flashes in accordance with the volume of the input voices.

Specifications:

  • Input – 6 VDC @ 300 mA
  • Output – Speaker, 8 Ω / 0.5 W
  • 7 Step level shifting (Volume Control) SW3 (TGU) and SW4 (TGD)
  • SW2 – Vibrato mode, SW5 – robot mode
  • LED to display the voice level input
  • ON/OFF slide switch for power supply
  • Audio amplifier type LM386 with volume control preset
  • PBT (Power Battery Terminal) connectors for supply voltage and speaker output
  • Power-On LED indicator
  • PCB dimensions 63 mm x 68 mm

CN1 – 6 VDC Supply Input
MIC1 – Electret Condenser Microphone
LS1 – Speaker

Schematic

Parts List

VOICE_MODULATOR_BOM

PCB

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