Dilshan R Jayakody’s Web Log

In this project we design miniature stereo computer speaker driver using TDA2822 power amplifier IC. Main goal of this project is to design small stereo power amplifier which may be able to fix inside the small speaker boxes. Supplied PCB of this project has dimensions of 4.5cm × 4.5cm, which include both power amplifier and PSU. Some of important technical specifications of this project are listed in below, Recommended Supplied Voltage : 5V – 9V AC Output Power : (with 8Ω load and 7.5V AC Power Source) : 2 × 1W Voltage Gain (with feedback) at 1kHz input signal : 38.5dB Total Harmonic Distortion : (with 8Ω load and P 0 = 150mW) 0.2% Channel Separation : 50dB When wiring the project it is recommended to place screen-wires to the input terminals of amplifier and keep them separate (away) from AC power lines and transformer unit(s). It is not necessary to install heatsinks to TDA2822M IC (with given input and output parameters). Complete schematic, PCB design and documen...

A7VVYNHHASU7

In this project we developed 4 inputs (Audio and Video), remote control operated video switch for general home use. This design is mainly based on Microchip PIC16F630 8bit MCU, 4052 differential 4 channel analog multiplexer, TSOP1838 infrared receiver module and 7447 BCD to seven segment decoder. With a given schematic and PCB design users can switch 4 different audio and video sources using compatible remote controller. Current version of this project is work only with most of Sony remote controllers (which based on Sony SIRC protocol) and it can be easily extend to Philips RC-5 protocol with some minor modifications of PIC16F630 software system. In this design we incorporate small single transistor video amplifier to its output stages to amplify the (chroma) part of video signal. Audio output stage of this system may not need any AF amplifier. (In the designing stages we notice some clipping of input signal in 4052 analog multiplexer, but it is not much noticeable in practical e...

Nowadays DSL splitter is a common unit in telecommunication and it is used by most of the ADSL users to obtain the maximum performance of the connectivity. Technically DSL splitter is an analog LPF (low pass filter) which is used to prevent interferences between analog telephone device(s) and DSL support units. In this project we describe how to build miniature ADSL splitter at home with grater simplicity and with minimum amount of cost. To build this unit user need to use few generic components which include pairs of 330µH inductors and 1R resistors, 0.0033MFD capacitor and three units of RJ11 PCB connectors. We successfully test this splitter with our local ADSL connection and it gives equal performance of commercial DSL splitter. The complete schematic and PCB diagram (Eagle) of this ADSL splitter is available to download at google drive

Few months back I got an old Heathkit IO-12 Oscilloscope from my friend and at the time of delivery this unit is not under the working conditions. Heathkit IO-12 is Value based laboratory oscilloscope with following technical features, Frequency Response : 3 Hz to 4 MHz ≅ 5 MHz Sensitivity : 0.025V/inch Rise time: 8µS Sweep Range : 10 Hz to 500 kHz When I remove the casing of the oscilloscope I found several damaged components (specially capacitors) and wires. After making the careful observation and testings I decided to rewire the whole oscilloscope with new components except the following, 12BH7 Dual Triode 12AU7 Dual Triode 6AN8 Triode Pentode 6AB4 Triode 1V2 ½ Wave Rectifier 6X4 Full Wave Rectifier 6J6 Dual Triode Main Transformer Front end controls (including switches, potentiometers, connectors and indicator) Most of the inductors Cathode Ray Tube, etc As mentioned in the above list all the Values, transformers and some of the critical components are in good condition. Only t...

Sudoku is one of my favorite games and in this project we developed small computer program to play and solve Sudoku puzzles in Microsoft Windows operating systems. Like all of my other computer programs this project is also hosted in sourceforge.net with open source – free software license (Under the terms and conditions of GNU General Public License Version 3 ). This project is developed using Borland C++ and it had following general features, Sudoku Game Panel with multiple user profiles Support custom board styles Auto-play options for all the predefine and user specified puzzles Minimize to tray option Three game play levels (as easy, intermediate and hard) Easy to add any number of custom puzzles Latest version of Mini Sudoku is available to download at minisudoku.sourceforge.net and at Mini Sudoku Ohloh project page . To modify this project user need to use Borland C++Builder 6, NSIS (Nullsoft Scriptable Installer) and Adobe Photoshop (or any other image editor which is capabl...

In this project we design an Inverter to convert 12V DC power source to 230V AC power. This system consist 3 main stages such as oscillator, switching circuit and step up transformer stage. In oscillator we use 4047 CMOS astable multivibrator to generate nearly 60Hz oscillation. In a given configuration, f = 1/(4.4C 2 (R 1 +R 2 )) f = 1/(4.4×(0.1/10 6 )((3.3+33)×10 3 ))) f = 62.609 Hz In a switching stage we use 2SD400 NPN transistors and IRFZ44 N-channel FETs. For the step-up transformer it is recommended to use 12V-0-12V : 230V – 5A transformer. When constructing the circuit it is highly advisable to apply good heat sinks to both Q1 and Q2. If you are plan to use single heat sink to both Q1 and Q2 it is required to place good insulator between the transistors and the heat sink. During the field test we use 12V - 7Ah sealed lead acid battery (which was commonly used in general UPS) with this system and constructed prototype deliver 238V AC in no-load. To get the c...