Hardware Laboratory – Part 11: Audio Design

   Your Hardware  Laboratory is almost ready. But we probably loosing any details. When you work with the driller machine for a long time or use the station for reflow with the compressor for heated air, your entire ear’s structure – middle, the inner ear system is tired.

   After that noisy invasion, the best medicine for the ears is a listening the quality music with an optimal loudness level. The missing stage of our Hardware Laboratory is the hand-made music box. 

   We will help you to choose.

   Our suggestion for creating that box is to use D-Class Type Digital Audio Amplifier. Switching or PWM Amplifiers are devices with high efficiency, commonly above 90%. The Speakers and the layout of the device leave your imagination and in your hands.


Block Diagram 1    D-Class Amplifier: General Principe Review 

  D-Class Amplifier:

  Principe of work.

  We Use The Comparator Unit {C.U.} and Triangular Wave-Generator connected on the positive {C.U.} Input.

  On the Negative {C.U.} input we applying wished to be amplified Low-level Signal to becomes modulated:  PWM Equal Signal. This PWM signal is carrying through the Switching Controller with Push-Pull Output Stage to get magnified or amplified By POWER. The Digitized Squared Signal passing through the next stage – the LOW PASS Filter, and recovered in the original shape signal is powering with “crystal sound” the Loud Speaker on the Output.

   There are many technical suggestions for that in the global Hardware market. We decided to represent only two variants – the first one is 2 x 25Watts rated output power and the second is with 2 x 50 Watts output power with the equal functionality.

   We decided to represent only two variants – one 2x25W  and second 2x50W with the similar functionality, because of one main reason:  Namely, The Digital, Class-D Amplifier modules have integrated Bluetooth {CSR8635 Based} Module, which is Android and IOS Compliant  with Media player Control using AVCRP {Audio/Video Remote Control Profile} and our favorite Advanced        Audio Distribution Profile {A2DP}. Whole that connectivity is fully integrated into the described modules.

   Bluetooth with The AVCRP features will allow us to control media playback with paired devices.

   The AVRCP profile works together with A2DP profile. 


Variant 1.




Variant 2 .


The main differences between two described devices are only mechanical and related with power output :  Amplifier Chip of Version 1 is TDA7492P can assume 2 x 25Watts vs TDA7492 used into the Version 2 can maintain 2x 50 Watts. 


Device Features:
   When You Use this Digital Amplifier, You can get an astonishing Sound quality.
   Module Integrates CSR8635 Bluetooth IC with Bluetooth V4.0 support.

  • Integrated Power amplifier: IC- TDA7492   up to 50W per Channel  which is better than TDA7492P,
  • Integrated Microphone allows managing calls via Bluetooth,
  • Wired AUX input interface,
  • 5-buttons interface for managing the player functionality-  PLAY,  BACK,  NEXT,  VOL+,  VOL-,
  • Supported Impedance of the Loud Speaker: {4 to 16 ohms}  – 8 ohms get the best results.

General Specifications:

  • Supply Voltage: DC 10V÷25V
  • Audio:Bluetooth V4.0
  • Amplifier Chip: TDA7492 
  • Rated Power: 2*50W
  • Speaker Impedance: 4..16 Ohms
  • Count of Channels: 2-channel Stereo 
  • PCB Board Size[cm]: 81mm x 58mm
  • PCB Board Size[inches]: 3.2incehs  x 2.3 inches
  • Weight: 47 grams.




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