Dilshan R Jayakody’s Web Log

This is an Android application to send Morse code messages using tones or flash (light) signals. This application supports for basic Latin alphabet, Arabic numerals and it can transmit messages with specified speed which can vary from 100ms to 500ms. Main application view  This application is developed using Delphi XE5 and it supports for Android version 2.3.3 ( Gingerbread ) to 4.2 ( Jelly Beans ) except Android version 3.2 ( Honeycomb ). This application is specifically design for 3.4 inch - 5.0 inch Android smartphones and we tested this application with few Huawei , Samsung and HTC devices. Audio / Visual Morse code Generator is an open source software project and its source code is available at http://github.com/dilshan/signalman . Compiled package is available to download at http://github.com/dilshan/signalman/releases . This project is distributed under the terms of MIT license . Delphi Android compiler platform is still evolving and some bug can be expecte...

This a quick post regarding homemade 300V - 2.3A isolation transformer. This transformer is a part of my ongoing 300V AC/DC variable power supply project and it’s boxed as a separate unit because of its heavy weight and size. 700VA isolation transformer with enclosure All the parameters of this transformer are calculated using small Python script which I was written sometimes ago. This script support for step-up, step-down or 1:1 power transformer windings and it can execute on any platform where Python 2.7 (or newer version) is supported. In isolation transformers separation between primary and secondary windings is an important factor. In this transformer I use multiple layers of 3M Scotch Electrical Insulation tape as primary and secondary winding separator. Standard 50mm PVC electrical insulation tape is used to cover secondary winding of this transformer. Improper connections or construction of this transformer may leads to fire or lethal electrical shock. Because of...

ALU (Arithmetic and Logic Unit) is a digital system that performs integer arithmetic and logical operations. In this post we introduce ATmega169 base ALU simulation using Proteus . This is 8bit ALU, and functionally it is similar to other entry level ALUs such as Motorola MC14581, 74LS181, etc. This unit can perform 80 arithmetic and logic operations and all these operations are listed in below of this post. schematic of ATmega169 base 8bit ALU simulation Firmware of this ALU is developed using AVR-GCC. While at the development we try to isolate firmware with platform as maximum as possible, because of that, this firmware can be modified to run on top of PIC , 8051 or MSP430 MCUs with minor set of changes.

This is oscillator controller for 8bit PIC microcontrollers which is specifically design to debug MCUs and related circuits by without using ICD unit. This unit consists with low speed oscillator and cycle counter with automatic hold. In current version, oscillator is capable to run in 2 frequency modes and it can count up to 4096 cycles in each run. The number of frequency modes can be extend by adding more capacitors and the upper limit of cycle counter can be increase by adding more 12bit counters (and related circuitries) to the system. Oscillator waveform in low frequency mode In current version oscillator can be run in either 66 Hz ~ 70 Hz or 666 Hz ~ 670 Hz ( aprox. ). This frequency can be adjusted by changing the value of C1 or C2 capacitors (e.g: 0.1MFD can generate 6.39 kHz output signal) OR by replacing R1 with some suitable variable resistor. In project package we include sample PIC16F84A based project to test with this system. The recommended test attachment i...

Now a days 3.3V PSU is essential for microcontroller, programmable logic devices and for some analog components also (especially with some new ADCs). This is ultra-simple 3.3V power supply unit, which is suitable for above mentioned experiments. This power supply is based on, ON semiconductor’s MC33269T-3.3 LDO regulator and it is capable to deliver 3.3V output with maximum of 800mA current. External view of 3.3V Power Supply The PCB design supplied with this article is also compatible with LD1117V33 (also known as LD33V) LDO regulator and it can use with this PCB without any changes. Dimension of the given PCB is 70mm × 35mm and it is design with all through-hole components. Our PCB design for this PSU is available to download at google drive . Maximum input voltage for this module is 20V (DC) for MC33269T-3.3 and 15V (DC) for LD1117V33 (or LD33V). In our unit we use 230V – 9V (1A) step down transformer as AC input for this unit.

When it comes to Windows operating systems I highly addicted to the "Run" dialog box. Technically, to me it functions like a single-line command line interface . From Windows 95 to Windows 8.1, layout and the functionalists of "Run" dialog box is quiet identical. To extend the functionalists of "Run" dialog box we did some project call " QRun ". The main purpose of QRun is to provide more convenient user-interface to existing Windows "Run" dialog box. QRun window with Action menu entries   The key feature of QRun is its menu driven command and resource selector. This menu driven interface help end user to perform actions by without memorizing commands and/or parameters. Another feature of QRun is its macro commands. Using this feature end user can create custom actions for run dialog box. Other than above features QRun also had inbuilt support for win-bash . Because of this feature end user may be able to run GNU bash relat...

This is quick post about 3W constant current LED driver which I was design to combine with some homemade furniture piece. The main components of this system is LM311 voltage comparator and IRF9 5 40 P-Channel MOSFET. Schematic of 3W LED driver module This module is design to drive maximum of two 3W high power LEDs and it requires 8V - 10V DC (500mA) power source. In this given configuration this module may not need any heat-sink (for IRF9540) and consume maximum of 500mA of power. Breadboard version of 3W LED driver At prototyping stages we test this module using 9V DC (1A) power supply with two 3W LEDs (EDEX-3LA1-E1). I developed final version of this module using piece of strip-board and PCB design is not done.