Archive for the ‘Audio’ Category

A month ago while browsing at ebay I came across this Bluetooth Audio Receiver and its on sale so I gave it a shot. At first it is a little difficult because all literature available are all in chinese, but luckily I found a readable manual. The exact model of this module is BLK-MD-SPK-D. I found out that there are several models and they look the same.Bluetooth Module

Finally when it arrived, I quickly made a breakout board to test its functionality, and it turned out it sounds great and its stereo. Eagle library and manual can be downloaded from the link below for those who need it.

Breakout Board

Eagle Files and Manual Download Link Click Here


I’ve been in digital electronics for a while, so I decided to combine my knowledge with analog electronics. This project is a modular amplifier based on LM3886 50W monolithic amplifier from National Semiconductor configured as non-inverting amplifier. The preamplifier and tone control module is based on TDA7313 digital controlled preamplifier via I2C with PIC16F88.

The Amplifier Module

The circuit is based on Jim George Six Channel Mixer and Amplifier configured as non inverting amplifier with a gain of 23.

Tone Control Module

The TDA7313 schematic is based on the datasheet, with the addition of a 7809 regulator. I added the regulator since the other modules are working on different voltage level so any accidental voltage input will not destroy the unit.

Controller Module

The Microcontroller is a PIC16F88 using internal oscillator, with 3 buttons for menu and navigation and a 2×16 LCD for display, like the other module, an onboard regulator is on board.

Actual Modules

LM3886 Amplifier Modules

TDA7313 Tone Control

Microcontroller, LCD and Buttons

Demo Video

Project Files in PDF and hex file for MCU can be downloaded from here

Since I was introduced to Class D amplifiers, I built several low power amps based on TI TPA3122D2 and TPA3123. I’m very satisfied with the results, one is used on our desktop PC and one on my brother’s motorcycle. There was a group buy at of the DR100W Kit from 1DiyCentre and there are two excess kits, since my LM1875 was put to rest a few days back, I decided to take one of the two.

Here is my Project Log during the Assembly of the Kit

The PCB and Components

The surface mount components was presoldered on the board

The TDA8920BTH is in HSOP24 package, the pitch is not so tight still pretty easy to solder.

All components soldered except for potentiometer since I will use digital controls for these one.

Finally the heatsink installed

Testing and first impression of this amp will follow

REBOTE 2.5 Delay

Posted: November 5, 2009 in Audio

Decided to build this delay from to many build reports says that this delay gives a warm analog sound so i decided to give it a try!

The populated PCB ready for testing