Wednesday, April 16, 2014

Audible Morse code to text message converter

Morse View is an open source software project to convert audible Morse codes to text messages. This application is capable to convert Morse codes from wave files or from the audio line/microphone inputs. Conversion from Morse code to text can perform based on amplitude and frequency decomposition of the input audio stream.

Morse View decoding 25 WPM Morse code wave file

We extensively test this application using Morse code files available at ARRL - W1AW code practice page. During the testing we may be able to use this application to decode 5WPM – 40WPM Morse code inputs. As per our test result, after 25WPM, accuracy of the decoder is heavily depends on the quality of the sound card / audio capture device (ADC) and with the system configuration. We test this system with few audio adapters, and out of those adapters both Creative Sound Blaster X-Fi and VIA VT1723 generate more accurate results, especially on 25WPM – 40WPM range.


We test this software with different noise configuration which including ±80% white noise, ±95% pink noise, etc. Under all these conditions decoder may be able to decode the messages with 96.3 – 99.81% accuracy.

This application is developed using Delphi XE5 and complete source code is available to download at sourceforge.net/projects/morseview. Morse View project is distributed under the terms of GNU General Public License Version 3.0.

Sunday, April 6, 2014

300V AC/DC Variable Power Supply

This 300V AC/DC variable PSU is designed for our vacuum-tube, MOSFET and some IGBT related experiments. This PSU consist with 0-300V Variac (variable auto-transformer), 700VA isolation transformer, which is described in previous blog post and high voltage AC-DC converter. Because of the size and weight of these equipment’s we build this PSU as three separate units.

Complete view of 300V AC/DC variable power supply unit.

This PSU is capable to supply 20V - 300V 2.3A (max.) output in either AC or DC form. This PSU use high voltage and because of that, all the proper construction and precautions are necessary to take. Improper wiring or construction may leads to lethal electrical shock and/or fire. If you are not familiar with high-voltage practices do not attempt this project at home.

Schematic of this PSU is available to download at http://elect.wikispaces.com.

Thursday, March 27, 2014

Audio / Visual Morse code Generator for Android

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 expected in this stage. If you found any bugs in this application please let us know via an e-mail.

Saturday, March 22, 2014

Home produced 700VA isolation transformer

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 that reason, make sure to take all the necessary precautions while constructing, testing or using this transformer. Do not try this project if you don’t know what you are doing!