Dilshan R Jayakody’s Web Log

This active subwoofer filter system provides the frequencies required to run the subwoofer within its limits. The purpose of this unit is to prevent the subwoofer speaker or circuit from overloading at unsupported frequencies. This approach can ensure the safety of the subwoofer speaker or driver circuit. This system consists of TL074 based active lowpass filter, highpass filter, and preamplifier stage. The lowpass filter is in 880Hz cutoff frequency. Highpass filter cutoff frequency can select from the rotary switch. In this given design, the highpass cutting frequencies are at 80Hz, 115Hz, 150Hz, and 180Hz.  Use the calculator application shown here to use this system for frequencies other than those mentioned above.  Finished prototype of an active subwoofer filter circuit. In this circuit, both lowpass filter and high pass filter uses a 3-pole Butterworth filter configuration. Here all the filter component values are calculated using the calculator application mentione...

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 c...