Home Projects Audio Voice Echo


Voice Echo
author: Rajkumar Sharma

This project is a Voice echo module with build-in amplifier and on-board mic.


A project has been designed around Holteks Ht8970 voice echo IC.  Project can be used in various audio systems karaoke, toys, animatronics, show, display, exhibitions, and sound equipment’s.

The HT8970 is an echo/surround effect processor. It is designed for various audio systems including karaoke, television, sound equipment’s, etc. The chip consists of a built-in pre-amplifier, VCO or Voltage Control OSC, 20Kb SRAM, A/D and D/A converters as well as delay time control logic.


Supply Input 5V DC
Onboard MIKE and Aux audio input
MIKE and Aux and selection via jumper
Input/MIKE signal level adjustable via preset
It can work in two modes - echo or surround
Output signal level adjust via preset
Onboard preset for sound delay
Onboard LED for power supply indicator
Four mounting holes of 3.2 mm
PCB dimensions 79 mm x 70 mm


download schematic in PDF


Parts List

PCB Design

PCB bottom layer






120x90 spot



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