Dilshan R Jayakody’s Web Log

This is a quick post regarding my Commodore64 Power Supply restoration. This C64 is my first computer and two days back its power supply get burn because of some short circuit in its output connector. This is a first time I open this C64 PSU and its internal circuitry is really simple to track down. Commodore64 Power Supply Unit Main component of this PSU is its 6 terminal step-down transformer. Other than that its circuit it limited to 2 rectifier diodes, 7805 positive voltage regulator, 2 - 1W resistors and 4700 µF /16V electrolytic capacitor. In my C64 PSU, defective component is 7805 voltage regulator, once I replace it and rewire the output terminal its starts to work again (like good old days). Commodore64 Power Supply Schematic Above diagram illustrate the schematic of my C64 PSU (which I was traced using original PCB). The high resolution images of PSU, are available at my flickr photo collection .

This is an easy to build "liquid level monitor" and "automatic control system". This control system is mainly based on Microchip’s PIC16F630 8bit MCU and few combinatorial logic ICs. This system is specifically design for industries where there is a requirement of maintaining a liquid level at a particular level. The level monitoring stage of this system can capable to sense up-to 8 liquid levels and its trigger point can be programmed at anytime by using its simple 2 button user-interface. This system is design to work with 12V (or maximum of 25V) DC power source and its sensor system is capable of sensing liquids with resistance of up-to 30k to 35k. To minimize the sensor noise and output instability, the control software is equipped with simple 20-tap FIR like filter system. The output stage of this system is design to work with 12V to 24V DC relays and it is recommended to use Tyco K10 series or similar kind of relay with this system. The trigger point o...

LSI Computer System's LS7220 is a digital code lock system for automotive systems. This LS7220 integrated circuit is difficult to find in many places and because of that we design some alternative system which simulate the functionality of LS7220 code lock system. This simulated system executes on top of the PIC16F628A 8bit MCU and it release as an open hardware project. LS7220 is a "hard-wired" code-locking system, but this simulated system provides both "hard-wired" and customizable (re-programmable) code locking options. This re-programmable feature provides some higher degree of protection to the system and it allows user/administrator to change system’s code at any given time by without changing the wiring layout(s) of the system. Pinouts of Programmed MCU In this project PIC16F628A MCU use its internal 4MHz oscillator and because of that it doesn't require any external clocking source(s). This system is design to work with 5V DC power supply...

This is an easy to build high quality echo sound generator and it’s completely based on Princeton Technology’s PT2399 echo sound IC. This supplied circuit is specifically design to interface with electronic musical instruments (e.g: electronic audio synthesizers, electronic organs, etc.) and with microphone systems. This echo sound effect generator requires 12V - 25V DC power supply and it can deliver aprox. 20W output power (with 8 Ω speaker and 20V - 5A DC power supply). This given design of echo sound generator has 3 main controls, such as echo delay adjustment, echo-effect mixer and master volume control. This delay and mixing ratio is heavily depended on input source. Output of C1 note with maximum and minimum echo effects At the testing stage we test this system with lot of input sources. According to our experiments this system can product good results with slow speed music and it produce excellent results with the voices. When it comes to high speed music (with ma...

nanoide is an effort to build scriptable build tool with source code editor. Initially I developed this tool to test some of my ongoing compiler projects and later I extend it with source code editors and with simple UI. nanoide build 138 with sample build script nanoide build system is based on FreePascal style scripting system and it comes with more than 50 inbuilt support functions . With help of nanoide, users can create complex conditional build flows and it helps to automate system testing processes also. Current version (build 145) of nanoide editor support C/C++, Java, Pascal/Delphi/Lazarus, Python, HTML, XML, CSS, Perl, Basic/Visual Basic, SQL, Tex, DOS batch scripts and UNIX\Linux shell scripting. nanoide is developed using Lazarus and it can be compiled and execute on Windows, Linux and Mac OS platforms. Virtually nanoide is compatible with any command line-driven compiler and it is tested with TinyC Compiler , Lua , Python , FPC and with PHP .  ...

This post is about simple Atmega325 development board which I was designed and build to test some large AVR systems. This development board contains ATmega325 MCU and MAX232 base RS232 driver/receiver unit. Thanks to SMD packages and components dimensions of this board get limited to 85mm × 62mm. This development board requires 5V external power supply and all its external circuitries (RS232 driver and hardware CPU reset) can be enable/disable through on-board jumpers. ATmega325 Development Board PCB design of this development board supports only for ATmega325 - TQFP64 package and MAX232 - SO16L package. This ATmega325 Development Board is release as an open hardware project and all its design files are available to download at google drive .

LEDShoot is a simple electronic shooting game which we developed in a year end vacation period. This is a single player electronic game with following game play logic: There are two fighting groups are exists in this game world. RED group is an enemy group and GREEN s are friendly parties. Player’s job is to shoot the RED group(s) when they appear on the stage. Player gets limited time to shoot and misfires are treated as negative points. When player get 100 points game get end with winning message. This electronic game system is mainly based on ATmega32 MCU and firmware is developed using GCC C (with Atmel Studio 6.0). This system is design to work with 5V - 1.5A power supply unit. We developed this system as a hobby project and we construct it on a couple of breadboards, at the moment we don’t have any PCB design for this project. When assembling the circuit make sure to use some heavy-duty push button for ( SL2 ) control key. For ( SL1 ) use 8 Ω - 1W (60mm) sp...