Dilshan R Jayakody’s Web Log

This project introduces a digitally controlled 5.1 channel audio preamplifier system. This amplifier is specifically designed to increase the gain of the multi-channel PC sound cards. The main reason for building this amplifier is the limited gain received from the ASUS Xonar AE sound card with the Creative Inspire T6300 , 5.1 surround speaker system. Before switching to this soundcard, we had a Creative Sound Blaster Z card which provided good audio output with the above-mention speaker system. The key motivation of building this amplifier is to solve these gaining problems. The assembled 5.1 preamplifier PCB. This preamplifier consists of six TL074 / TL072 preamplifier stages and PT2258 electronic volume control. The input stage of this preamplifier consists of six TL074 / TL072 buffer stages. The PIC16F886 microcontroller manages the PT2258 electronic volume control IC. All the volume levels and menu options are displayed on HD44780 , 16x2 character LCD screen . All the ...

USB Morse Keyer is a microcontroller-based auto keyer project with following features: USB / straight key / iambic key inputs. Support for both standalone and USB operating modes. 64-character USB typeahead buffer and 6-character Morse key typeahead buffer. Support 5, 10, 15 WPM. 6-page message memory. 1W Audio output. Audio and PTT output interfaces. 32 character display  Final view of the USB auto keyer. The USB interface of this unit is designed to work with most of the operating systems. It emulates a virtual serial terminal to transfer keystrokes to the keyer. In most of the operating systems, this interface works without installing any additional device drivers. To submit keystrokes user can use any serial terminal software such as PuTTY , Hyper Terminal , Minicom , etc. This keyer is designed to work with 7V to 16V DC input voltage. The most recommended working voltage is 9V. The bottom side of the USB auto keyer. To reduce the dimension of the P...