Wednesday, December 14, 2011

Digitally Controlled Audio Power Amplifier with Virtual Surround Sound

In this post we describe digitally controlled 2.1 channel audio power amplifier with virtual surround sound. This audio amplifier is based around Microchip’s PIC18F452 microcontroller and ST microelectronics TDA2050 power amplifiers.

Key system specifications and features of this audio system are listed in below:
  • Supply voltage and PSU: D.C - 16V to 19.5V with 3A PSU. (Recommended: 18.8V, 3A PSU)
  • Input(s): 2 analog input lines. (for Left and Right channels)
  • Functions: Volume, Bass, Treble, Loudness, Mega Bass, Surround Effects
  • Volume control: 0dB to 75dB Attenuation per channel with 1.25dB step
  • Mute: 100dB Attenuation per channel
  • Calculated channel separation (Approximately): 85dB - 88dB
  • Bass control: ±14dB with 2dB step
  • Mega bass control: 0dB to 30dB with 7 control steps
  • Treble control: ±14dB with 2dB step
  • Surround Sound: Based on AViSS 3D surround algorithm with 4 operational modes (Disable, Low, Normal and Wide)
  • Output channels: 3 (2 channels + 1 subwoofer driver channel)
  • Output power: 20W (PMPO) in 8Ω load
  • Output power of subwoofer channel: 20W (PMPO) in 8Ω load
  • Recommend speaker configuration: 2 × 30W 8Ω full range speaker(s) for 2 output channels. 1 × 4Ω 50W woofer for "subwoofer driver channel".
  • Control interface: IR remote control with SIRC protocol
Other than above features this system equipped with digital UV meter (for both the input channels) and complete menu system.

Tuesday, November 1, 2011

An open scriptable USB interface for host driven electronic experiments

SigLab is a combination of open hardware and FOSS (free and open source software) projects to provide easy to use and full featured scriptable USB interface for digital electronic experiments. SigLab USB interface consisted with Microchip's PIC18F2550 microcontroller unit and it provides 14 bidirectional (digital) I/O ports for external interfacing.

Scriptable language of SigLab had some resemblance to Pascal programming language and this system provides complete IDE for script editing and debugging.

Current version of SigLab offers following core features to its users:

  • Provide easy to use USB controller for digital electronic projects
  • Avoid complexities of USB peripheral programming by providing full featured, easy to use scriptable interface
  • Introduce DIY - USB controller with standard electronic components
  • Provide live workspace to debug/watch hardware and firmware operations
All the SigLab source codes, design files and other reference documents are available to download at

Sunday, September 4, 2011

Microprocessor controlled CW Beacon

In this project we introduce portable microprocessor controlled CW radio beacon. This CW beacon module is capable to transmit maximum of 64 Morse codes repeatedly in 4.433MHz with 9V DC power source.

This system consists of CW transmitter, ATtiny13 microcontroller unit and low current voltage regulator. Atmel ATtiny13 microcontroller is used to drive the transmitter and thanks to its internal 64 byte E²PROM, we may be able to change beacon data without altering the system firmware.

While at the testing stages we receive this beacon on 10km radius (using Sony ICF-SW7600GR receiver) by using standard telescopic antenna. To get the maximum range it is recommended to use 3m – 4m antenna wire with this transmitter system. At the prototyping /testing stages we try this transmitter successfully with 3.58MHz, 4.43MHz and 6.00MHz crystals.

This system is design to work with standard 9V battery (6F22/6LR61). At the prototyping stages we test this system using 12V and 10V DC power sources and get the same results.

Transmitter of this system is based on Nyle Steiner’s (K7NS) "80m CW transmitter" unit. All the project source codes, schematic diagrams and PCB patterns are available to download at

This project is released as an open hardware project and all the source codes are licensed under the terms of GNU General Public License Version 3 and all the documents, schematics and PCB patterns are licensed under the Creative Commons Attribution-ShareAlike 3.0 license.

Monday, August 1, 2011

Ultra Simple Microchip PIC Development Board

In this project we develop easy to build Microchip PIC development board for widerange of PIC Microcontrollers (which include 40pin Microchip PIC16 and PIC18 devices).

This development board contain only the switching regulator (to generate +5V DC from the input power source) and RS232 serial port interface. The switching regulator of this development board may support input voltage of +8V to +25V DC. RS232 Serial interface of this development board is based on Maxim's MAX232 driver/receiver IC.

This given design have 6 two-way jumpers to select crytal osciliator, MCLR and RS232 Tx/Rx terminals.

While at the protyping stages we test this board successfully with PIC16F887, PIC16F877/A, PIC18F452, PIC18F4550 and PIC18F4620 MCUs. Diamensions of this PIC Development Board is 110×85mm.

Schematic, PCB design and some of the related documents of this project are available to download at google drive.

Sunday, June 26, 2011

XBMC USB Controller for Media Center PCs

In this project we develop USB port base controller for XBMC application. Main functionality of this controller unit is to provide remote control interface, LCD base - player information panel and rotary encoder base controller for XBMC. With this given hardware design and software programs, user may be able to control XBMC without using standard input devices such as keyboard and mouse.

This device is design to work with XBMC Version 10.1 (codename Dharma) or newer versions. Older version of XBMC may not work this system because of the differences in its Web Control Interface.

PIC18F4550 is a main hardware controller of this system. This microcontroller is used for USB interfacing, as LCD driver, IR base remote control data decoder and as a driver of the other input devices (such as rotary encoder and push switches). Controller’s USB interface is design to work as USB HID class device.

This system is design to work with Microsoft Windows Operating Systems and we test this system in Windows XP Professional editions and some few Windows XP embedded editions also.

XBMC USB Controller is an open hardware project. All the project source codes and computer programs are released under the terms of GNU General Public Licenses Version 3.0. All the schematic diagrams and PCB files are release under the terms of Creative Commons Attribution-ShareAlike 3.0 license. All the project contents including software programs and design files are available to download at google drive

Sunday, June 5, 2011

PIC16F877A/PIC16F887 Microcontroller Development Board

In this post we introduce easy to build, full featured PIC16F877A/PIC16F887 microcontroller development board. This development board contains following core features:

  • RS232 interface
  • PS/2 host interface
  • Battery backup - Real Time Clock with I2C interface
  • Highly precision 1-wire thermometer interface
  • 4 Digit Seven Segment Display module
  • HD44780 compliant LCD module
  • 4×4 Keyboard
  • 4 button onboard joystick
  • 8×2 LED driver
  • 8bit peripheral driver interface
  • 8bit Digital to Analog converter module
  • 36kHz Photo module for Infrared base inputs
  • Wide supply voltage range from 12V – 40V

To reduce the form-factor we design this system in a double sided PCB. When constructing this project make sure to use exact component values for PSU module (especially for L1, R1 and R2).

When constructing the circuit do not connect R4 and R5 wires to the PCB. Both these wire links are providing to isolate the PSU from main board. After constructing the circuit power on the PSU and check the voltage between R4 and R5. Under normal operating mode voltage between R4 and R5 is 4.8V – 5.03V.

LM2576-5.0 is also compatible with this board. If IC1 is LM2576-5.0, make sure to replace R1 with wire and open R2 resistor in the PCB.

It is required to install suitable heatsink to the LM2576 switching regulator. 20V (3A) D.C. power source is recommended for this PSU.

This development board is compatible with any HD44780 compliant LCD module. While at the testing stages we check this LCD interface with several 1602E-1 LCDs and all these modules provide excellent results to us.

This development board is released as an open hardware project and licensed under the Creative Commons Attribution-ShareAlike 3.0 license.

All the project schematic files and PCB designs are available to download at google drive.

Saturday, April 16, 2011

Mini Servo Controller

In this project we introduce easy to build, miniature servo controller. This miniature servo controller system is ideal for most of the robotic and mechanical projects. Some of the most notable key features of this project are:

  • Tiny PCB design (35mm × 33mm aprox.) using standard through-hole components.
  • Support for both analog and digital control interfaces.
  • Compatible with most of the servo units.
  • Low cost due to small amount of components.

The main controller of this project is PIC12F675 – 8bit CMOS microcontroller. In this given design we configure PIC12F675 microcontroller to operate using its 4MHz internal oscillator.

This designed servo controller may successfully work with any generic servos which include MYSTERY, Futaba, HiTec, JR Radio, etc. At the prototyping stages we test this controller with several MYSTERY 3.7g and 9g servos.

This servo controller is design to work in 2 operating modes. In first mode this system may work with analog potentiometer and control the servo according to the value of potentiometer. In the second mode servo is controlled using 3 tactile push switches. These operating modes are selected using jumper on the controller PCB. This servo controller is design to work with 4.5V – 5.5V DC power source.

All the project schematic files, PCB designs and firmware source codes are available to download at google drive.

Friday, April 8, 2011

Open Hardware Logo Selected!

Open Hardware community selected “Golden Orb” by Macklin Chaffee as the OSHW Logo v1.0. Congratulations Golden Orb!

You can also get open hardware definition from this link: Visit Open Hardware Summit – home page to get more information and updates about “Open Hardware”.

Saturday, February 19, 2011

Electric Fence with Automated Monitoring System

Electric Fences are designed to create an electrical circuit when touched by person (or animal). The circuits proposed in this article release 10kV electrical pulses to the fence-line and monitor the line status. This entire system is design to drive using 25V (5A) single-rail DC power source (using 5A power supply unit or pair of 12.6V Lead-Acid batteries).

Main controller of this system is Microchip PIC12F675 – 8bit microcontroller. All the line monitoring, pulse generation and alarm system controlling is performed by this microcontroller.

Some of the most notable features of this system are built-in audible alarm system, contactless fence line monitoring system, Support for wide range of step-up transformers (up to maximum of 10kV) and compact 10cm × 10cm PCB design.

This system use standard electronic components (through-hole components) and SMD components in this provided PCB layout. All the project documents, schematics, PCB designs and firmware source codes are available to download at google drive.

Saturday, January 8, 2011

32W Hi-Fi Audio Power Amplifier using TDA2050

In this project we develop 32W hi-fi audio power amplifier using TDA2050 integrated circuit. The main objective of this project is to provide common high gain audio amplifier for DIY kind of projects.

In this given PCB pattern, both the power amplifier and PSU are limited to the 53mm x 65mm printed circuit board. This circuit is design to work with 15V – 18V (AC) supply voltage and it is highly recommended to use suitable step down toroidal transformer with this system.
All the PCB patterns and schematic diagrams of this project are available to download in google drive.

Saturday, January 1, 2011


This DIY project happens because of some request of my family members. The ultimate goal of this project is building analog TV antenna to receive UHF and VHF channels with minimum distortion, noise, materials and time.

All the building materials of this antenna are available in general electronic shops and hardware stores.

I got excellent results from this antenna in my home town: Maharagama (Colombo, Sri Lanka) with all the locally available VHF and UHF channels.

Technical drawing of this antenna is available to download in here.