Wednesday, October 22, 2014

Optically controlled servo motor

This is demonstration project to control servo motor movement using physical marker and normal video camera. In this project video camera capture the movements of marker and calculate rotation angle based on that. This calculated rotation angle is feed to the servo through small MCU based interfacing unit.

In this project video processing and tracking is performed using ARToolkit and controlling of servo is carried out using PIC16F628A microcontroller. RS232 interface is use to communicate between PC and microcontroller.

Interfaces in optical servo controlling system

This application detects movement of marker on Z axis (yaw) and transforms it into another numerical scale to manipulate the servo motor. Processing application is written using Visual C++ and configured to work on Windows operating system(s). The marker used for this application is needed to be a "square with some symbol" and user can train this system for any compatible marker. As per our tests, standard 3MP or higher grade web cam is sufficient for this system.

prototype assembly of servo driver and servo unit

To demonstrate the exact behavior video is much more suitable but my web cam is used for this project and I don’t have spare web cam to capture the operation of this project. As per our observations servo movement is highly sensitive to the changes of marker object and the movement of the servo motor is also linear and smooth. The propagation time is little bit slow due to serial interface and this can be improved by using high speed I/O interface like USB port.

The source code, servo driver schematic and firmware of this project are available to download at elect.wikispaces.com under the terms of the GNU General Public License version 3.0.

Saturday, October 11, 2014

Digitally controlled 2.1 channel analog audio power amplifier

This article introduces high quality digitally controlled 2.1 channel analog audio power amplifier system. This project is mainly based on TDA7377 AF power amplifier and PIC18F452 8bit microcontroller. Basic features of this receiver are 2 × 6W + 20W audio output power, ±14dB bass and treble controls, fully configurable +35dB bass booster for sub-woofer and satellite speakers and loudness switch.

This system use commonly available electronic components and all the integrated circuits are in DIL packages. This amplifier consists with few UI elements such as 2 push buttons and 1 rotary encoder. All the menu navigation can perform through rotary encoder.

Prototype version of 2.1 channel audio power amplifier project

Entire amplifier can build on 147mm × 80mm PCB and all the PCB design files are available to download at project homepage.

This is an open hardware project and all the firmware source codes, design files are covered with Mozilla Public License version 2.0. All the above content and complete documentation is available to download at http://elect.wikispaces.com.

Thursday, September 4, 2014

Trio JR-310 and TX-310 restoration project

I got Trio (now Kenwood) JR-310 and TX-310 SSB receiver and transmitter pair recently. When it comes to me both receiver and transmitter are in very bad shape and most of the PCBs and chassis are covered with dust and some of the components are very badly damaged. After examining both the chassis I decided to repair both units because of its vintage value (and also I like to try some tube base SSB receiver and transmitter pair).

Trio JR-310 is AM, SSB and CW mode HF receiver. This receiver has 3.5, 7, 14, 21, 25 and 50MHz operating bands and sensitivity is around 1µV. This receiver consists with 6 vacuum tubes, 5 transistors and 19 diodes. JR-310 which I restored is working with 110V and total power consumption is around 70W.

Bottom view of restored JR-310 receiver

TX-310 is 20W SSB transmitter and designed to match with JR-310 receiver. It is capable of LSB, USB, AM and CW transmissions in HF bands. This unit consists with 10 vacuum tubes, 5 transistors and 9 diodes. Like JR-310, this unit also working with 110V power source.

S2001 final stage vacuum tube and high voltage area of TX-310

I did restoration of above mentioned TX-310 and JR-310 step-by-step and most of the steps are listed in my qsl.net pages.

Saturday, August 16, 2014

Eddystone EC10 communication receiver restoration and PSU add-in

Recently I got vintage Eddystone EC10 MK1 communication receiver from friend of mine and it is completely dead when it comes to me. EC10 MK1 is one of Eddystone's very early solid state communications receivers and it use 10 PNP Germanium transistors. This receiver cover 550 kHz to 30 MHz and come up with BFO for CW and SSB receptions.

Restored EC10 MK1 HF communication receiver

The main problems which I noticed in my EC10 is corroded wires, components and PCB. I did restoration step-by-step and most of the steps are listed in my qsl.net page.

Other than repairing, this article covers details of power supply which I integrated into EC10 communication receiver. The schematics and photographs are available at the same article.

After repairing and above changes EC10 starts to work again and with some external antenna is performs quiet well. Most of the times I use this receiver to listen to 40m 4S7RS net on 7060kHz.