Dilshan R Jayakody’s Web Log

Microscopic view of EEPROM IC

2012-02-01T19:58:00.004+05:30

This is a Microscopic view of Fairchild Semiconductor's MBM27C64 E²PROM IC and ST Microelectronics M27C512 E²PROM IC.

M27C512

MBM27C64

Homemade 2.1 Audio Power Amplifier System

2012-01-05T12:14:00.005+05:30

This post show completed view of digitally controlled audio power amplifier with virtual surround (which we described in previous post). All the speaker enclosures, power amplifier casing and electronic system are design and developed by us. Configuration of this given step is as follows:

System Components: Power Amplifier, 2 main speaker units, 1 sub-woofer and 18V (5A) SMPS.

Speaker System: Main speaker system consist with 8Ω (45W) 6½ inch Woofer, 8Ω (50W) 3 inch Tweeter with passive crossover.

Subwoofer System: 3Ω (200W) 8 inch Bass Woofer.

All the speaker enclosures are mad out of 9mm MDF (medium density fiberboards) and power amplifier casing is made using 2mm acrylic sheets.

More views of this audio system are available in here.

Digitally Controlled Audio Power Amplifier with Virtual Surround Sound

2011-12-14T19:15:00.003+05:30

In this post we describe digitally controlled 2.1 channel audio power amplifier with virtual surround sound. This audio amplifier is based around Microchip’s PIC18F452 microcontroller and ST microelectronics TDA2050 power amplifiers.

Key system specifications and features of this audio system are listed in below:

Supply voltage and PSU: D.C - 16V to 19.5V with 3A PSU. (Recommended: 18.8V, 3A PSU)
Input(s): 2 analog input lines. (for Left and Right channels)
Functions: Volume, Bass, Treble, Loudness, Mega Bass, Surround Effects
Volume control: 0dB to 75dB Attenuation per channel with 1.25dB step
Mute: 100dB Attenuation per channel
Calculated channel separation (Approximately): 85dB - 88dB
Bass control: ±14dB with 2dB step
Mega bass control: 0dB to 30dB with 7 control steps
Treble control: ±14dB with 2dB step
Surround Sound: Based on AViSS 3D surround algorithm with 4 operational modes (Disable, Low, Normal and Wide)
Output channels: 3 (2 channels + 1 subwoofer driver channel)
Output power: 20W (PMPO) in 8Ω load
Output power of subwoofer channel: 20W (PMPO) in 8Ω load
Recommend speaker configuration: 2 × 30W 8Ω full range speaker(s) for 2 output channels. 1 × 4Ω 50W woofer for "subwoofer driver channel".
Control interface: IR remote control with SIRC protocol

Other than above features this system equipped with digital UV meter (for both the input channels) and complete menu system.

An open scriptable USB interface for host driven electronic experiments

2011-11-01T21:55:00.006+05:30

SigLab is a combination of open hardware and FOSS (free and open source software) projects to provide easy to use and full featured scriptable USB interface for digital electronic experiments. SigLab USB interface consisted with Microchip's PIC18F2550 microcontroller unit and it provides 14 bidirectional (digital) I/O ports for external interfacing.

Scriptable language of SigLab had some resemblance to Pascal programming language and this system provides complete IDE for script editing and debugging.

Current version of SigLab offers following core features to its users:

Provide easy to use USB controller for digital electronic projects
Avoid complexities of USB peripheral programming by providing full featured, easy to use scriptable interface
Introduce DIY - USB controller with standard electronic components
Provide live workspace to debug/watch hardware and firmware operations

All the SigLab source codes, design files and other reference documents are available to download at github.com/dilshan/SigLab.

Microprocessor controlled CW Beacon

2011-09-04T15:34:00.003+05:30

In this project we introduce portable microprocessor controlled CW radio beacon. This CW beacon module is capable to transmit maximum of 64 Morse codes repeatedly in 4.433MHz with 9V DC power source.

This system consists of CW transmitter, ATtiny13 microcontroller unit and low current voltage regulator. Atmel ATtiny13 microcontroller is used to drive the transmitter and thanks to its internal 64 byte E²PROM, we may be able to change beacon data without altering the system firmware.

While at the testing stages we receive this beacon on 10km radius (using Sony ICF-SW7600GR receiver) by using standard telescopic antenna. To get the maximum range it is recommended to use 3m – 4m antenna wire with this transmitter system. At the prototyping /testing stages we try this transmitter successfully with 3.58MHz, 4.43MHz and 6.00MHz crystals.

This system is design to work with standard 9V battery (6F22/6LR61). At the prototyping stages we test this system using 12V and 10V DC power sources and get the same results.

Transmitter of this system is based on Nyle Steiner’s (K7NS) "80m CW transmitter" unit. All the project source codes, schematic diagrams and PCB patterns are available to download at elect.wikispaces.com.

This project is released as an open hardware project and all the source codes are licensed under the terms of GNU General Public License Version 3 and all the documents, schematics and PCB patterns are licensed under the Creative Commons Attribution-ShareAlike 3.0 license.

Ultra Simple Microchip PIC Development Board

2011-08-01T20:01:00.005+05:30

In this project we develop easy to build Microchip PIC development board for widerange of PIC Microcontrollers (which include 40pin Microchip PIC16 and PIC18 devices).

This development board contain only the switching regulator (to generate +5V DC from the input power source) and RS232 serial port interface. The switching regulator of this development board may support input voltage of +8V to +25V DC. RS232 Serial interface of this development board is based on Maxim's MAX232 driver/receiver IC.

This given design have 6 two-way jumpers to select crytal osciliator, MCLR and RS232 Tx/Rx terminals.

While at the protyping stages we test this board successfully with PIC16F887, PIC16F877/A, PIC18F452, PIC18F4550 and PIC18F4620 MCUs. Diamensions of this PIC Development Board is 110×85mm.

Schematic, PCB design and some of the related documents of this project are available to download at elect.wikispace.com.

XBMC USB Controller for Media Center PCs

2011-06-26T16:59:00.003+05:30

In this project we develop USB port base controller for XBMC application. Main functionality of this controller unit is to provide remote control interface, LCD base - player information panel and rotary encoder base controller for XBMC. With this given hardware design and software programs, user may be able to control XBMC without using standard input devices such as keyboard and mouse.

This device is design to work with XBMC Version 10.1 (codename Dharma) or newer versions. Older version of XBMC may not work this system because of the differences in its Web Control Interface.

PIC18F4550 is a main hardware controller of this system. This microcontroller is used for USB interfacing, as LCD driver, IR base remote control data decoder and as a driver of the other input devices (such as rotary encoder and push switches). Controller’s USB interface is design to work as USB HID class device.

This system is design to work with Microsoft Windows Operating Systems and we test this system in Windows XP Professional editions and some few Windows XP embedded editions also.

XBMC USB Controller is an open hardware project. All the project source codes and computer programs are released under the terms of GNU General Public Licenses Version 3.0. All the schematic diagrams and PCB files are release under the terms of Creative Commons Attribution-ShareAlike 3.0 license. All the project contents including software programs and design files are available to download at elect.wikispaces.com

PIC16F877A/PIC16F887 Microcontroller Development Board

2011-06-05T17:44:00.008+05:30

In this post we introduce easy to build, full featured PIC16F877A/PIC16F887 microcontroller development board. This development board contains following core features:

RS232 interface
PS/2 host interface
Battery backup - Real Time Clock with I2C interface
Highly precision 1-wire thermometer interface
4 Digit Seven Segment Display module
HD44780 compliant LCD module
4×4 Keyboard
4 button onboard joystick
8×2 LED driver
8bit peripheral driver interface
8bit Digital to Analog converter module
36kHz Photo module for Infrared base inputs
Wide supply voltage range from 12V – 40V

To reduce the form-factor we design this system in a double sided PCB. When constructing this project make sure to use exact component values for PSU module (especially for L1, R1 and R2).

When constructing the circuit do not connect R4 and R5 wires to the PCB. Both these wire links are providing to isolate the PSU from main board. After constructing the circuit power on the PSU and check the voltage between R4 and R5. Under normal operating mode voltage between R4 and R5 is 4.8V – 5.03V.

LM2576-5.0 is also compatible with this board. If IC1 is LM2576-5.0, make sure to replace R1 with wire and open R2 resistor in the PCB.

It is required to install suitable heatsink to the LM2576 switching regulator. 20V (3A) D.C. power source is recommended for this PSU.

This development board is compatible with any HD44780 compliant LCD module. While at the testing stages we check this LCD interface with several 1602E-1 LCDs and all these modules provide excellent results to us.

This development board is released as an open hardware project and licensed under the Creative Commons Attribution-ShareAlike 3.0 license.

All the project schematic files and PCB designs are available to download at elect.wikispaces.com.

Mini Servo Controller

2011-04-16T13:17:00.005+05:30

In this project we introduce easy to build, miniature servo controller. This miniature servo controller system is ideal for most of the robotic and mechanical projects. Some of the most notable key features of this project are:

Tiny PCB design (35mm × 33mm aprox.) using standard through-hole components.
Support for both analog and digital control interfaces.
Compatible with most of the servo units.
Low cost due to small amount of components.

The main controller of this project is PIC12F675 – 8bit CMOS microcontroller. In this given design we configure PIC12F675 microcontroller to operate using its 4MHz internal oscillator.

This designed servo controller may successfully work with any generic servos which include MYSTERY, Futaba, HiTec, JR Radio, etc. At the prototyping stages we test this controller with several MYSTERY 3.7g and 9g servos.

This servo controller is design to work in 2 operating modes. In first mode this system may work with analog potentiometer and control the servo according to the value of potentiometer. In the second mode servo is controlled using 3 tactile push switches. These operating modes are selected using jumper on the controller PCB. This servo controller is design to work with 4.5V – 5.5V DC power source.

All the project schematic files, PCB designs and firmware source codes are available to download at elect.wikispaces.com.

Open Hardware Logo Selected!

2011-04-08T07:43:00.005+05:30

Open Hardware community selected “Golden Orb” by Macklin Chaffee as the OSHW Logo v1.0. Congratulations Golden Orb!

You can also get open hardware definition from this link: http://freedomdefined.org/OSHW. Visit Open Hardware Summit – home page to get more information and updates about “Open Hardware”.

Electric Fence with Automated Monitoring System

2011-02-19T13:44:00.006+05:30

Electric Fences are designed to create an electrical circuit when touched by person (or animal). The circuits proposed in this article release 10kV electrical pulses to the fence-line and monitor the line status. This entire system is design to drive using 25V (5A) single-rail DC power source (using 5A power supply unit or pair of 12.6V Lead-Acid batteries).

Main controller of this system is Microchip PIC12F675 – 8bit microcontroller. All the line monitoring, pulse generation and alarm system controlling is performed by this microcontroller.

Some of the most notable features of this system are built-in audible alarm system, contactless fence line monitoring system, Support for wide range of step-up transformers (up to maximum of 10kV) and compact 10cm × 10cm PCB design.

This system use standard electronic components (through-hole components) and SMD components in this provided PCB layout. All the project documents, schematics, PCB designs and firmware source codes are available to download at elect.wikispaces.com.

32W Hi-Fi Audio Power Amplifier using TDA2050

2011-01-08T20:48:00.001+05:30

In this project we develop 32W hi-fi audio power amplifier using TDA2050 integrated circuit. The main objective of this project is to provide common high gain audio amplifier for DIY kind of projects.

In this given PCB pattern, both the power amplifier and PSU are limited to the 53mm x 65mm printed circuit board. This circuit is design to work with 15V – 18V (AC) supply voltage and it is highly recommended to use suitable step down toroidal transformer with this system.
All the PCB patterns and schematic diagrams of this project are available to download in here.

DIY UHF/VHF TV Antenna

2011-01-01T15:11:00.003+05:30

This DIY project happens because of some request of my family members. The ultimate goal of this project is building analog TV antenna to receive UHF and VHF channels with minimum distortion, noise, materials and time.

All the building materials of this antenna are available in general electronic shops and hardware stores.

I got excellent results from this antenna in my home town: Maharagama (Colombo, Sri Lanka) with all the locally available VHF and UHF channels.

Technical drawing of this antenna is available to download in here.

Programmable Home Security Alarm System

2010-12-04T10:01:00.003+05:30

In this project we design low cost high performance programmable home security system using few LDR’s as an input sensors. When above sensor(s) get triggered system may dial the user specified phone number (using build-in DTMF generator) and activate the high power audio alarm and lights. All the parameters of DTMF generator, audio alarm and light interface are programmed through the RS232 serial interface.

Current firmware of this system presents interactive control system through the RS232 interface. This control system consist with the menu driven configuration options, self tests, system report generators, etc.

This system also contain 5W (with 4Ω speaker) audio alarm with three selectable tone configurations, which include Police siren, Fire engine siren and Ambulance siren.

This system uses a Microchip’s PIC16F877A as a main controller, LM339 as sensor interface, UM3561 as a tone generator and μPC2002 as a speaker driver (audio amplifier). LM7805, LM7812 and LM317 voltage regulators are used to obtain +5V, +12V and +3V respectively.

All the project source codes, schematic diagrams and PCB patterns are available in http://elect.wikispaces.com with terms and conditions of GNU GPL and Creative Commons - Attribution-ShareAlike 3.0 Unported license.

Low Voltage Simple Motor Speed Controller

2010-09-26T10:41:00.003+05:30

While designing some mechanical projects we often have need for easy to build motor speed controllers. Thanks to the SGS-THOMSON Microelectronic’s TDA7274, now we have easy to build, low voltage D.C motor speed controller. TDA7274 provides wide operating voltage range from 1.8V to 6V and in this project we use it to drive small CD-ROM ejection motors.

In this project we design entire speed controller with 39.3mm × 28.9mm PCB. While at the prototyping we test this system with 5V power source and successfully control several CD-ROM ejection motors, cassette motors and toy D.C motors.

You can obtain all the circuit diagrams, PCB patterns and other information of low voltage motor speed controller from elect.wikispaces.com.

2 Channel Electronic Motor Speed Controller

2010-09-20T08:15:00.001+05:30

In this project we design 2 channel D.C motor controller with pulse width modulation (PWM) based speed and direction control. This module is mainly design to drive 14.4V to 18V electric D.C motors.

This motor controller is design to work with 18V - 1.5A D.C power source and it can be directly interface with general microprocessor / microcontroller system (without using any voltage level shifters). While at the prototyping stages we successfully couple this module with several NIDEC D.C fans and blowers which include D1751M24B7AP, E1331K12B7AZ-00, DME37KA, CF24DM506, etc.

Control interface for this module is easy to use and at the designing stages we interface it with PIC16F887 and Atmega64 MCUs. Control interface of this module is consisting with 3 inputs (please refer the J3 in the circuit diagram) and using these inputs user may be able to select the motor, apply the brakes and also change the rotational directions of the motor(s).

When constructing the circuit it is recommended to use 680R - 1W wire wound resistor for R10. Heatsink attachments for both Q1 and IC1 are depending on the output load.

All the project schematics and PCB patterns are available to download at http://elect.wikispaces.com.

Processing OpenOffice.org dictionary files using Lazarus

2010-08-18T09:55:00.011+05:30

In this article we demonstrate how to processing OpenOffice.org dictionary files using Lazarus – FPC IDE. To use the OpenOffice.org dictionary first we need to extract AFF file and DIC files from the OXT (OpenOffice.org extension) file. This can be easily done using 7Zip or any other generally available file archiving utility. (Only thing we need to do is change OXT file extension to ZIP and extract the contents)

To process this dictionary (DIC) file we need to use affix table defined in the AFF file. In this sample code we implement the complete AFF and DIC file processor for English (United States) dictionary of the OpenOffice.org.

Our processing of this affix file in this sample application is based on the following rules,

AFF file generally consist with some conditional modules as follows,

SFX T N 4
SFX T 0 st e
SFX T y iest [^aeiou]y
SFX T 0 est [aeiou]y
SFX T 0 est [^ey]

In the first line "SFX" means suffix. In En(US) dictionary this may be either SFX or PFX.

T is the name of the module (and this helps us to establish the link between DIC and AFF file)

Digit 4 indicates the number of rules for the given condition.

Once read the conditional header you need to cross product the rule set with the given word.

Rule set of the given condition is decode as follows,

SFX : as previously described SFX is a suffix.
0 : This indicates strip off character and in here 0 means NULL.
st : Suffix for the give word
e : This represents the logical part of the rule. In here "e" means target word might need to be end with the character "e".

Example for this rule is : Late > Latest

Likewise you need to apply all these rules to the root word and make all other possibilities for the word.

For example root word "happy" may have 4 forms, such as,
Happier, Happiest, Happiness and Unhappy.

This sample application is developed using Lazarus with minimum amount of system dependencies to demonstrate the above decoding process. With some minor adjustments this can be easily deployed to the Linux and Mac OS X also.

All the source codes and binaries of this sample application are available to download in here. This sample application is deployed under the terms and conditions of GNU GPL Version 3.0.

You can obtain more details about AFF and DIC files from the OpenOffice.org Lingucomponent Project.

Fixing the "Self Checking" problem of Panasonic DMR-E55 DVD Video Recorder

2010-07-02T08:03:00.007+05:30

I have Panasonic DMR-E55 DVD Video Recorder and suddenly it start to get reboot when the system performs “Self Checking”. Because of this reboot problem I may not be able to record DVDs and need to put some extra effort to eject the disks. Most of the times this reboot occurs in cyclic pattern and to break this cycle I need to be eject the DVD disk manually from the system.

While examine the system my primary attention moves on to the “Digital RAM card” of the system (Because it actively involves in to the DVD burning process). But after the 2 weeks of continues inspection I found that the problem is in the SMPS primary chip - STR G6535.

After replacing the STR G6535, system starts to work in an order.

Replacement of this chip is not a complex process but while doing that it is necessary to put some attention about the SMD components located nearby.

8 Channel USB Logic Analyzer

2010-05-16T12:31:00.005+05:30

Logic analyzers are allowing us to monitor and /or diagnose a large number of digital signals simultaneously and these devices are essential when developing complex digital systems. In this project we design simple 8 channel USB logic analyzer with Windows version of driver software.

Design of this logic analyzer is based around Future Technology Devices FT245 USB FIFO chip. With the given oscillator this system takes 14MSPS (Mega samples per second) and this system is design to work as (USB) self powered device (without any external power source).

Driver part of this project is based on FTD2XX driver and GUI is developed using Delphi. Current version of driver software is design to work with Windows NT operating systems and it is highly recommended to use it with 1360 × 768 or with higher video resolutions (with aspect ratio of 16:9).

This design also contains real-time logic level indicators to monitor "low frequency" signal levels and construction of that portion is not much essential.

When constructing the circuit take special care about IC1 – 4069 Hex Inverter (in this design it mainly worked as CMOS Pierce - Gate oscillator), because at the time of testing we found that some of the chips may not produce proper output and finally it get affected to the entire system (including driver software). In our prototype we use Fairchild’s CD4069UBCN as IC1.

All the project source codes, binaries, schematic diagrams and PCB patterns are available in http://elect.wikispaces.com with terms and conditions of GNU GPL.

8 feet - home made C band satellite dish antenna

2010-04-24T21:46:00.004+05:30

In this project we design 8 feet C band satellite dish antenna and some of its specifications are listed in below,

Diameter of the reflector : 248.0cm
F/D ratio : 0.391
Focal length : 914.6cm
Calculated gain (Aprox.) : 40.23 dB

Materials used for reflector : Aluminum sheets and Aluminum nets
Number of panels (in reflector) : 4 units
Materials used for Mounting mechanism : Steel
Weight (Aprox.) : 40 - 45 kg (without antenna positioning system)

LNBF : Generic dual twin C band LNBF
Antenna positioning system : Using D.C motorized actuator

Repairing Sony PlayStation 2 Game Console

2010-04-12T14:40:00.007+05:30

One of my friend had Sony PlayStation 2 (SCPH-39000 series) game console and in few months back it get fail because of the internal short-circuit due to spill of some liquid over the game console. Finally he sends it to me to repair it, and I found some problems in both PSU (Power Supply Unit) and motherboard of the console.

In first round of the repair I replace IC807 (78M05), PS013 fuse and all the related parts near that area (because I notice some burn marks in that location) except IC806 (NJM12904). Other than that I replace R278 (1.5k), R279 (1K + 100R), R491 to R495 (with wire links), R470 (100K), Q415 (2SC2873), Q406 (IRF7901, I got this transistor from another old PS2 game console main board, available in junk store), F001 (with some 42 S.W.G copper wire) and D404 (with 3 × 1N4148 diodes).

When I replace and re-solder some of the parts as described above, I got the video signal (PS2 startup splash and main menu) from the console. But system may not produce any audio signals (in both left and right channels of audio output). Finally I check the audio part of the system and found that the problem is in final stage of audio DAC (IC517 - Cirrus Logic CS4335 - 24-Bit, 96 kHz Stereo digital to analog convert chip). Once I replace that chip (thanks to old PS2 game console main board which I was purchased from the junk store) this system may get start with both audio and video.

Once the system is up and running I attach the battery and other assemblies to the board and finalize the repairing process.

If someone like to repair Sony PlayStation 2, following points are important to him/her (according to my experiances),

Before make any repairs, disconnect the mains supply and battery supply from the main board.
Make sure to place insulations sheet between the PSU and Shield B (Shield located at the bottom side of the main PCB).
Most of the components of main board are SMDs. So it is necessary to have good SMD Rework Station to carryout any component level repairs.
There are several flexible ribbon cables in this system. Handle them with proper care.
Do not adjust any potentiometers, trimmers and coils located on the main board, PSU and Optical Pickup.
There are several heat transferring sheets are located on the bottom side of the main PCB. (e.g : heat transferring sheets attached to the IC802 - BA5815 and IC803 - BA6664). Make sure to attach them properly when setting up the Shield B.

Electronic Number Panel

2010-03-28T16:52:00.001+05:30

In this design we present an electronic number display panel using low cost and low power electronic components. This proposed design is mainly based on CD4510 - CMOS up/down counter and SN74LS47 - BCD-to-Seven-Segment Decoder/Driver. With the existing configuration, this counter may be able to count (up/down) from 00 to 99 and it can easily extend to more digits by setting up additional CD4510 and SN74LS47 chip pairs.

Current system is also equipped with the beeper (which based around NE555 timer IC) to indicate the increment or decrement of the count.

This system is design to work with DC 9V – 12V (500mA) power supply and at the time of testing we use 10V (2.5A) DC power source to check this system. This proposed system contain 7805 regulator and it is necessary to apply suitable heat-sink to this regulator.

In this project, we design PCB using double sided PCB and make dimensions and shapes according to the existing enclosure of old electronic number panel system. It is not necessary to follow it, as it is.

The complete schematic diagram and PCB pattern is available to download at http://elect.wikispaces.com

Virtual MCU Base Programmable Timer

2010-03-23T21:11:00.001+05:30

In this article we implement virtual (computer simulation base) microcontroller driven programmable timer using Proteus VSM. This proposed system is design using Microchip PIC16F877A – 8bit microcontroller and its system software is developed using MikroC PRO 3.2 for PIC. Most of the components in this proposed design are based on Proteus VSM - simulation models and we assign standard component names to them to assist in actual prototyping.

In this simulation we use PIC16F877A as main system controller and 4 row monochrome LCD display unit with HD44780 compliant controller (in 4bit mode). This proposed simulation model is design to work with +5V supply voltage, but it can also operate using battery power (3 × 1.5V).

When implementing this system for the real-life use, it is highly recommended to integrate battery backup facility to this system. It helps to drive this system continuously with minimum amount of disturbances.

According to the supplied source code, end user may be able to program start time and end time of the timer or specify only the start time. Once the timer get started user may be able to terminate the timer by pressing “OK/Timer Disable” key.

Please note that this system is provided only for demonstration purposes and end user need to calibrate MCU crystal and other associated components to obtain exact 1Hz clock trigger. The Lamp (L1) shown in the simulation model is for the demonstration purposes only. Ignore this component at the prototyping stages. All the source codes and Proteus ISIS simulation files of this project is available to download at elect.wikispaces.com.

8 pin 2 digit seven segment display driver

2010-03-04T08:36:00.006+05:30

This is a simple microcontroller base implementation to drive 2 digit 8 pin seven segment display (SSD) unit. For this implementation we use Microchip’s PIC16F84A – 8bit microcontroller unit and Proton+ PICBASIC compiler. Compared with other SSD units this SSD unit needs special algorithm to drive it. Some of the logical procedures to drive this SSD unit are illustrated in below,

This illustration is valid only for single digit of target SSD unit and it can easily expand to 2 digits by activating pin no 5 and 6 with appropriate inputs.

In attached design we use PIC16F84A MCU with 4 × 2SC945 general purpose NPN transistors to drive this TOD-4201LR SSD unit. This proposed system is design to work with +5V DC power supply and may not need any additional data source.

Supplied software for this project is for demonstration purposes only and it perform counting from 0 to 99 and then reset back to 0. To generate the output user need to assign required number to the value variable and make jump to the show_num section of code. According to the given lookup table this software may be able to generate digits from 0 to 9 and “E”, “-“ and “.” symbols.

All the source codes and schematic diagram of this project is available to download at http://elect.wikispaces.com

Ultra Simple Stereo Computer Speaker Driver

2010-02-18T22:09:00.001+05:30

In this project we design miniature stereo computer speaker driver using TDA2822 power amplifier IC. Main goal of this project is to design small stereo power amplifier which may be able to fix inside the small speaker boxes. Supplied PCB of this project has dimensions of 4.5cm × 4.5cm, which include both power amplifier and PSU.

Some of important technical specifications of this project are listed in below,

Recommended Supplied Voltage : 5V – 9V AC
Output Power : (with 8Ω load and 7.5V AC Power Source) : 2 × 1W
Voltage Gain (with feedback) at 1kHz input signal : 38.5dB
Total Harmonic Distortion : (with 8Ω load and P₀ = 150mW) 0.2%
Channel Separation : 50dB

When wiring the project it is recommended to place screen-wires to the input terminals of amplifier and keep them separate (away) from AC power lines and transformer unit(s).

It is not necessary to install heatsinks to TDA2822M IC (with given input and output parameters).

Complete schematic, PCB design and documentation of this project are available to download at elect.wikispaces.com.

A7VVYNHHASU7

2010-02-14T16:07:00.002+05:30

A7VVYNHHASU7

4 Channel Remote Control Video Switch

2010-01-28T22:45:00.004+05:30

In this project we developed 4 inputs (Audio and Video), remote control operated video switch for general home use. This design is mainly based on Microchip PIC16F630 8bit MCU, 4052 differential 4 channel analog multiplexer, TSOP1838 infrared receiver module and 7447 BCD to seven segment decoder. With a given schematic and PCB design users can switch 4 different audio and video sources using compatible remote controller. Current version of this project is work only with most of Sony remote controllers (which based on Sony SIRC protocol) and it can be easily extend to Philips RC-5 protocol with some minor modifications of PIC16F630 software system.

In this design we incorporate small single transistor video amplifier to its output stages to amplify the (chroma) part of video signal. Audio output stage of this system may not need any AF amplifier. (In the designing stages we notice some clipping of input signal in 4052 analog multiplexer, but it is not much noticeable in practical environment/use.)

At the time of testing we use Sony RMT-V408 remote controller with this project and it produces successful results. Basically this project support only numerical keys between 1 to 4 and program Up/Down (+/-) buttons of remote controller.

This system is design to work with 5V supply voltage and to get the optimal results it is highly recommended to use well-regulated 5V – 750mA power supply with this unit. To reduce the interferences place screen-wires to both audio/video input/output lines and place them separately from AC main-lines and PSU transformer(s).

Note : With the given source code system may respond to any, compatible Sony SIRC protocol base remote controller, but this may get some problems in practical environment. To avoid this problem please validate the value of remote_sys variable with your target remote controller. In here I’m not implement it because I do not have any Sony SIRC protocol compatible products.

The complete schematic, source code and PCB designs of this project is available to download at elect.wikispace.com.

Homemade ADSL Splitter

2010-01-05T14:56:00.001+05:30

Nowadays DSL splitter is a common unit in telecommunication and it is used by most of the ADSL users to obtain the maximum performance of the connectivity. Technically DSL splitter is an analog LPF (low pass filter) which is used to prevent interferences between analog telephone device(s) and DSL support units.

In this project we describe how to build miniature ADSL splitter at home with grater simplicity and with minimum amount of cost. To build this unit user need to use few generic components which include pairs of 330µH inductors and 1R resistors, 0.0033MFD capacitor and three units of RJ11 PCB connectors.

We successfully test this splitter with our local ADSL connection and it gives equal performance of commercial DSL splitter.

The complete schematic and PCB diagram (Eagle) of this ADSL splitter is available to download at http://elect.wikispaces.com

Servicing Heathkit IO-12 Oscilloscope

2009-12-18T20:42:00.005+05:30

Few months back I got an old Heathkit IO-12 Oscilloscope from my friend and at the time of delivery this unit is not under the working conditions. Heathkit IO-12 is Value based laboratory oscilloscope with following technical features,

Frequency Response : 3Hz to 4MHz ≅ 5MHz
Sensitivity : 0.025V/inch
Rise time: 8µS
Sweep Range : 10Hz to 500kHz

When I remove the casing of the oscilloscope I found several damaged components (specially capacitors) and wires. After making the careful observation and testings I decided to rewire the whole oscilloscope with new components except the following,

12BH7 Dual Triode
12AU7 Dual Triode
6AN8 Triode Pentode
6AB4 Triode
1V2 ½ Wave Rectifier
6X4 Full Wave Rectifier
6J6 Dual Triode

Main Transformer
Front end controls (including switches, potentiometers, connectors and indicator)
Most of the inductors
Cathode Ray Tube, etc

As mentioned in the above list all the Values, transformers and some of the critical components are in good condition. Only the major problem occurs at the electrolytic capacitor replacement stage(s) because in original configuration there are two capacitors packs (4 Pin capacitor package with common ground) are available. It is bit difficult to obtain those capacitors from local market. So what I'm doing is installing 4 separate electrolytic capacitors, instead of one single electrolytic capacitor pack. To do this I'm slightly change existing component layout of the original IO-12 Oscilloscope. Except these capacitor modules all other parts are commonly available in local market. (with some slight differences in packages and values)

After the rewiring, this unit work nicely and produce results as same as today's professional analog oscilloscope. At the time of testing I couple this unit with one of my old Phillips GM4585 trigger delay unit and achieve successful results. The above photograph indicate this restored IO-12 oscilloscope with 50Hz - 12.75V peak to peak sine wave.

Mini Sudoku for Windows

2009-12-07T15:53:00.005+05:30

Sudoku is one of my favorite games and in this project we developed small computer program to play and solve Sudoku puzzles in Microsoft Windows operating systems. Like all of my other computer programs this project is also hosted in sourceforge.net with open source – free software license (Under the terms and conditions of GNU General Public License Version 3).

This project is developed using Borland C++ and it had following general features,

Sudoku Game Panel with multiple user profiles
Support custom board styles
Auto-play options for all the predefine and user specified puzzles
Minimize to tray option
Three game play levels (as easy, intermediate and hard)
Easy to add any number of custom puzzles

Latest version of Mini Sudoku is available to download at minisudoku.sourceforge.net and at Mini Sudoku Ohloh project page.

To modify this project user need to use Borland C++Builder 6, NSIS (Nullsoft Scriptable Installer) and Adobe Photoshop (or any other image editor which is capable to modify Photoshop psd files).

12V DC to 230V AC Inverter

2009-12-04T07:33:00.005+05:30

In this project we design an Inverter to convert 12V DC power source to 230V AC power. This system consist 3 main stages such as oscillator, switching circuit and step up transformer stage. In oscillator we use 4047 CMOS astable multivibrator to generate nearly 60Hz oscillation.

In a given configuration,

f = 1/(4.4C₂(R₁+R₂))

f = 1/(4.4×(0.1/10⁶)((3.3+33)×10³)))

f = 62.609 Hz

In a switching stage we use 2SD400 NPN transistors and IRFZ44 N-channel FETs. For the step-up transformer it is recommended to use 12V-0-12V : 230V – 5A transformer.

When constructing the circuit it is highly advisable to apply good heat sinks to both Q1 and Q2. If you are plan to use single heat sink to both Q1 and Q2 it is required to place good insulator between the transistors and the heat sink.

During the field test we use 12V - 7Ah sealed lead acid battery (which was commonly used in general UPS) with this system and constructed prototype deliver 238V AC in no-load.

To get the complete circuit diagram and Eagle PCB design please check the http://elect.wikispaces.com.

Automated Home Security System

2009-11-27T11:52:00.004+05:30

Automated Home Security system is PIC16F877 based security system with following core features,

Support automatic phone dialing using DTMF tones
Support inputs from three optical sensors
Control external device(s)
Built-in alarm with external audio output
Allow total customization to the end-users (such as program phone numbers, setup device control sequence, etc) without changing the source code.
Password protected system setup

In this design we use PIC16F877 8bit microcontroller as main system controller, NE556 dual timer as an alarm system and 7805 as power regulator. To miniaturize the final product we use some amount of surface mounted parts with this design. Application program(s) of PIC microcontroller is developed using C programming language and release under the terms and conditions of GNU General Public License.

In this design we use some special electronic components/modules which include LCD display module, 4x4 keyboard matrix, telephone isolation transformer, etc. At the time of circuit design we choose common, locally available parts for this design, which include,

HD44780 compatible LCD module
Custom made 4x4 Key Matrix
General 600Ω telephone isolation transformer
NTE-R22 3V relay

In this design we use PIC16F877 MCU to generate DTMF tones (with help of R-2R ladder circuit), as a LCD driver and as a general I/O controller. In PCB design we use generally available DIP version of PIC16F877. Except PIC16F877 and BC140, all other semiconductors are in surface mounted packages.

When installing the system (which means in a practical environment) it is recommended to use LASER pointer as a light source. During our field tests we get successful results with the 5mW LASER module.

In this project all the PCB patterns are design using EAGLE layout designer and all the source, component libraries and output files are available to download with the supplied package.

To get the complete project details (including schematic, PCB design and firmware source code and binaries) visit our project repository at http://elect.wikispaces.com

20W Hi-Fi Audio Power Amplifier

2009-11-17T08:20:00.003+05:30

TDA2030 is most popular, high quality - low cost audio power amplifier and successive version of TDA2006. Typically TDA2030 deliver 14W in 24V with 4Ω output load and 8W in 8Ω output load. Because of it’s wider power bandwidth (10Hz to 140 kHz) and extremely small amount of distortion (0.1% - 0.5%), TDA2030 deliver excellent sound quality with higher performance. In this project we design basic version of TDA2030 mono power amplifier for general use and its design to work with 9V – 24V (500mA) Power Supply Unit.

When building the circuit it is recommended to use PCB design and its important to attach suitable heat-sink to the TDA2030. In this design it is not necessary to have electrical isolation between the IC and the heat-sink.

To get the complete circuit diagrams and PCB designs (Eagle) please check the http://elect.wikispaces.com.

Low Dropout Single Rail Adjustable Power Supply Unit

2009-10-30T07:19:00.000+05:30

In this project we design high current, high accuracy single rail variable power supply unit using Micrel’s MIC29152 voltage regulator IC. Thanks to the Micrel’s Super Beta PNP fabrication process this regulator has 80mV to 600mV dropout at the full load. With the given values of R1, R2 and TR1, this unit delivers 1.3V to 20V with maximum of 1.5A current.

This power supply unit is ideal for most of the analog electronic experiments, as a simple battery charger, as laboratory power supply, etc. Complete circuit diagram, PCB pattern and Eagle source files of this project are available to download in here.

When building the circuit make sure to install suitable heat-sink to the MIC29152 chip. This circuit use 230V AC power source, so make sure to apply all the safety precautions while at the designing and testing phases.

AT89S52 base RPM counter

2009-08-04T07:17:00.000+05:30

In this design we use AT89S52 microcontroller to build inexpensive revs-per-minute meter. This meter can measure speed in the range of 1 to 9999 rev/min. This design was originally developed to measure the speed of brushless motors, but it can use for any application where the speed is in above mentioned range. In the given design input pulses are generated using Allegro A1203 Hall-effect bipolar switch and it can be replaced with any other Hall-effect sensor or IR detector.

Current version of RPM counter is based on Atmel’s AT89S52 8bit MCU and control software is developed using MikroC 8051 compiler.

At the time of implementation and testing we use Allegro A1203, A3517 and A3056 (for gear-tooth sensor operations) Hall-effect bipolar switches with this system and all these sensors produce excellent results with it.

AT89S52 source code and complete circuit diagram of this project are available to download at http://elect.wikispaces.com

PHPhD – Server side hardware port access extension for PHP

2009-07-27T07:29:00.009+05:30

In one of my project I need to access PC hardware ports using PHP. Standard distribution of PHP (PHP for Windows) may not have facilities to access PC/Server hardware ports, and finally I developed lightweight PHP extension to access server hardware ports.

Current version of PHPhD (version 1.0.0.20) support for PHP 5.2.x (tested with PHP 5.2.1) and distributed under the terms and conditions of Mozilla Public License version 1.1. This PHP extension is available to download at http://elect.wikispaces.com/Downloads

Using PHPhD users can access server hardware ports with minimum amount of coding and complexity. Example PHP source code which was based on PHPhD is listed in below,

//Initialize and open hardware device driver
if(!phphd_open_driver()) {
die("Unable to open PHP hardware port access device driver");
}

//read printer (LPT) port and get the curent port value
$lpt_port_val = phphd_read_port(0x378+1);
echo("LPT port value [0x378+1] : ".$lpt_port_val);

//close device driver
phphd_close_driver();
?>

Current version of PHPhD (version 1.0.0.20) has following functions,

phphd_open_driver : Function to load device driver and initialize the hardware access session.
phphd_close_driver : Function to close current device driver and release all the hardware sessions.
phphd_isopen : Function to get the initialization status of the device driver.
phphd_read_port : Read specified hardware port and return the value.
phphd_write_port : Function to write value to the specified hardware port.
phphd_sound : Function to trigger the system (server) speaker with given frequency and period. Most of the times we use this function to test the device driver and functionality of PHPhD.

Please note that this PHP extension is available for the Windows platforms only.

Low Cost and High Quality Stereo FM Radio Receiver

2009-07-23T07:03:00.002+05:30

In this project we build CXA1619BS base high performance FM stereo radio receiver using low cost and readily available electronic components. In this design we use CXA1619 as FM radio receiver and BA1320 as FM stereo decoder and LA4108 as power amplifier.

When building the circuit it is highly recommended to build it using the print circuit board (PCB) and take some necessary steps to reduce the effects of external interferences.

In this design we use BA1320 as stereo decode and user can also use BA1330 with this circuit with some less amount of input voltage. (For example: +5V) We use BA1320 for this design because of its low cost, low complexity, higher channel separation and higher availability.

In current design we use LA4108 as power amplifier and it delivers 6W x 2 output power at 8ohm load.

While assembling the circuit make sure to apply suitable heat-sinks to both 7805 voltage regulator and LA4108 power amplifier.

At the testing stages this circuit produces excellent results and fewer amounts of issues in tuning. Anyone can tune this circuit without using signal generator and oscilloscope.

It is recommended to provide 7V to 12V of supply voltage to this circuit and at the testing stages we use 8.0V PSU with this circuit.

Circuit diagram and assembling notes of this circuit is available in http://elect.wikispaces.com.

433MHz RF remote control system for RC Cars

2009-06-29T11:42:00.003+05:30

After the 2 weeks of continues development we finally design suitable RC remote control system for cars. This RC system has,

Battery eliminator circuit (BEC)
Control System
433MHz transmitter and receiver module
Motor driver and servo controller

In this design both transmitter and receiver modules are based on seeed studio’s 433MHz RF link kit and control systems are based on microchip’s PIC16F84A MCU.

At the design time we test this circuit with Futaba, Airtronics, JR-Radios, HiTec and "Mystery" (available in eBay) micro-servo units. This circuit may support standard electric motors (brushed DC motors) and during the testing stages we drive RC helicopter motors and RC airplane motors successfully with this system. To drive this circuit we use 7.2V 500mAh Li-Po batter pack.

During the circuit assembling and testing, make sure to take necessary actions (e.g: shielding) to prevent/minimize the EM interferences which was generated by the motors. Most of the time these EM noises may reduce the performances of the 433MHz receiver module.

To get the maximum performance use 830mm (or higher) telescopic antenna with the transmitter and 20cm antenna with the receiver.

We design this system for RC cars but it can also use with RC airplanes, helicopters and boats with some minor modifications to the receiver module.

All the circuit diagrams and MCU source codes are available to download at here.

Finding electronic parts and instruments in Sri Lanka

2009-06-01T09:46:00.005+05:30

Most of the times finding the electronic parts in Sri Lanka is (extremely) difficult process. Lots of electronic part suppliers have fast-moving electronic parts only. (such as general resistors, capacitors, semiconductor devices related to the Hi-Fis, TVs and general consumer electronic products, etc.) For my electronic experiments I'm getting most of these “uncommon” electronic parts from following suppliers,

Farnell : Farnell is my "number one" choice for most of the “uncommon” electronic parts and instruments, specially semiconductor devices and test instruments. Compared with other suppliers there prices are bit high but also had a nice service and higher reliability. Most (all ?) of there parts are coming from reliable and popular vendors. Most interesting thing is “There are no minimum order quantity levels in there orders”, which means I can order 1 unit of electronic part from them.

Orel Solutions (PVT) Ltd

No 49, Sri Jinarathana Road,
Colombo 2.
Sri Lanka.

Tel: +114 792103 / 105
Fax: +115 376678
Web: http://export.farnell.com

Silvertones Ltd : Silvertones is one the oldest electronic part supplier in Sri Lanka and they also have good collection of electronic parts. Most of the Silvertones parts are coming from branded electronic part manufactures, due to this reason some of there parts are bit expensive than standard once.

Silvertones Ltd

132 Vauxhall Street
Colombo 2
Sri Lanka.

Tel: +112 436141, 2 335634
E-mail: silvertones@eureka.lk

DigiKey : Digikey is one of the world's largest electronic component supplier and unfortunately there are no any local agents for DigiKey. I brought some hard to find electronic parts from them via online and there service is also excellent. Only problem in DigiKey is it's higher shipping and handling charges.

Web: http://www.digikey.com

Other than these local/international suppliers eBay have several electronic part suppliers. Most of them sell lot of rare semiconductors and other electronic components. Most of these eBay suppliers ship parts with free of charge and they are not much expensive as DigiKey or Farnell.

Compact logic probe with pulser

2009-05-12T08:46:00.005+05:30

Logic probe is an essential item for digital electronic fault findings and constructions. In this project we design compact and simple logic probe with digital pulse generator. This circuit is based on 4069 logic inverter and 7805 voltage regulator. In this design we use 4069 invert module to drive the LED of logic probe and to build the oscillator circuit.

We use TO-92 style of 7805 regulator to drive the 4069 chip and entire circuit can be build around 2.5cm x 12cm PCB (if you need to reduce the size in to more, use the SMD version of 4069 and 7805)

All the resistors are 1/8w and SMD versions are also acceptable.

To change the period of pulser modify C1 or/and R2.

Complete schematic of digital logic probe with pulser is available to download in here.

1.5A - 3V to 27V adjustable power supply using LM723

2009-05-12T08:08:00.004+05:30

In this project we developed 1.5A, 3V to 27V adjustable power supply unit based on LM723 voltage regulator IC. In this project we add some additional options to standard LM723 PSU circuit (available from National Semiconductors) to improve the safety and performance.

When assembling the circuit it is necessary to attach suitable heat sinks to both 2N3055 transistors. Single heat sink for both 2N3055 are also acceptable.

According to the initial design R8 must be 0.39ohms (5W), but most of the people say it is bit difficult to get 0.39ohms locally (Sri Lanka) so I change value of R8 to 0.47ohms (5W) and it is available in local market.

During the testings and usage this system produce an excellent results for us. Complete circuit diagram of the power supply unit is available to download in here.

PS/2 Keyboard driven Morse code Generator

2009-03-25T07:31:00.006+05:30

This is simple PIC microcontroller base project to generate Morse codes using standard PS/2 keyboard. This project based on Microchip’s PIC16F73 microcontroller and National semiconductor’s LM386 audio power amplifier. Software for PIC microcontroller is written using MikroC and all the source codes, schematic diagrams and other documents are available to download at here.

In this project we choose PIC16F73 because of it’s 4KW (KWords) program memory, it is possible to replace this MCU with any suitable MCU which having 4KW (or more) flash memory. (For example Atmel AT89C4051-24SJ with different source code, Microchip PIC16F648 with some minor changes in source code, etc)

Audio power amplifier of this project is based on National Semiconductor’s LM386. We choose LM386 because of its lower power consumption and compactness. User may also replace this module with suitable power amplifier (for example Philips TDA7052, TDA8551, National’s LM4906, etc.)

PIC16F73 software is developed using MikroC 8.1 compiler.

User Programmable Automatic Night Light

2009-03-17T07:51:00.002+05:30

In this project we developed user programmable automatic night light using Microchip's 8bit MCU – PIC12F675. In this design user may be able to program and store the time duration of the master light. Compared with other designs this circuit use transformerless power supply, and TRIAC to control the master light.

Complete MCU software source code, operating guides and circuit diagram of this project is available to download at here.

To get more information about transformerless power supply please refer the Microchip application note AN954, and ST application note AN438 for MCU and TRIAC interfacing.

3.3V – 1.5A Compact Power Supply Unit

2009-02-23T07:33:00.006+05:30

3.3V is now widely used in electronic circuit projects (especially in digital electronics). These days several MCUs, CPUs and Digital interfaces (e.g: USB, Ethernet) uses 3.3V and in this project we developed suitable compact power supply unit for these projects. This project is mainly based on National Semiconductors LM1086-(3.3) power regulator.

With the suitable transformer this circuit may capable to deliver 3.3V (during the testing stages we get 3.29V) with 1.5A of maximum current. If you need more current please use LM1085 (3A) or LM1084 (5A) instead of LM1086 (U1).

All the circuit diagrams and PCB patters for this project are located in here. To get the maximum performance, replace C2 and C3 with 10MFD/25V tantalum capacitors.

Please note that it is necessary to install good heatsink to the LM1086-3.3 (U1) regulator.

Automated Telephone Remote Control – Demonstration

2009-02-17T11:09:00.005+05:30

In this project we develop automated telephone remote control system to demonstrate the functionality of MT8870 DTMF decoder.

This project mainly based on MT8870 DTMF decoder and ATtiny2313 MCU. When this system connects to the phone line it monitor the status of the phone line and take the control of phone line when it detects the ringer, after that user may be able to control specified I/O port using appropriate keys.

Finally user can issue predefine key combination to shutdown the phone line.

Schematic diagram, source codes for ATMEL ATtiny2313 are available in here and all the source codes are developed using WinAVR (with Atmel AVR Studio 4).

Please note that this project is developed for demonstration purposes only, some of the system states may not handled with the given source code.

Low cost and low power VIA PC-1 Series mainboards

2009-02-10T15:59:00.005+05:30

These days we are working with VIA Technologies PC-1 series mainboards and compared with standard main boards these boards have special features and advantages.

Main advantage is, its lower price and low power consumption.

Like most modern motherboards these boards also have built-in Sound cards, Network adapters, SATA Support and build-in Video interface.

VIA PC-1 series is specially design for low power computing and users may be able to run this mainboard with 150W power supply.

There are several PC-1 mainboards are available and we are mainly worked with following units,

PC-1000 Mainboard

Powered by VIA C3 – 800MHz microprocessor
100/133 MHz FSB
DDR-I Memory up to 1GB.
VGA up to 64MB
4 USB 2.0 ports
10/100 LAN interface
1 PCI Slot
Realtek AC97 audio codec
Mini ATX form factor (170mm x 170mm)

Price : Rs. 5000.00 (Sri Lanka Rupees)

PC-3500 Mainboard

Powered by VIA C7-D – 1800MHz microprocessor
400/800 MHz FSB
DDR-II Memory up to 2GB
VGA up to 256MB
6 USB 2.0 ports
10/100 LAN interface
1 PCI and 1 PCIExpress x16 Slot
2 SATA Connectors
Realtek 6 channel audio codec

Price : Rs. 8500.00 (Sri Lanka Rupees)

During the testing phase we use PC-1000 with Fedora 9 and Windows XP, and PC-3500 with Windows Vista, Windows XP and Windows 7 Beta. Both mainboards provide excellent performance with following configurations,

Memory - 1GB (DDR/DDR-II)
Power Supply - 150W (20 pin)
Disk Drivers - 80GB IDE
Input Devices - PS/2 Keyboard and Mouse
Operating System - Windows XP Media Center Edition

We use PC-1000 mainboard for our control system experiments with slight modifications and it produces excellent results with following configuration,

Memory - 512MB DDR-I
Power Supply - 36V homemade PSU
Disk Drivers - N/A
Input Devices - PIC MCU base homemade Keyboard simulator
Operating System - Windows XP using Flash Drive (Build using BartPE)
USB Device - 2GB Kingston Data Traveler - USB Flash Driver.

PC-3500 is recommended for intermediate level home PCs.

Prithvi Development Studio for PIC Microcontrollers

2009-02-06T15:25:00.001+05:30

Prithvi Development Studio is my new project to build an IDE for GCBASIC – PIC Programming language. Prithvi is developed using Borland Delphi 7 programming language and currently it supports over 300 PIC Microcontroller devices.

This IDE is based on GCBasic, and GPUtils, so users can directly produce hex files from Basic source code without using any 3rd party tools. (e.g: without using Microchip’s MPLAB - ASM).

Current version of Prithvi Development Studio supports wide range of PIC 10F, 12x, 16x and 18x devices and Prithvi Development Studio also ship with wide range of GCBasic support libraries such as X10, LCD, ADC, RS232, USART, EEPROM, etc.

Current version of Prithvi Development Studio has following features,

Source code editor with syntax highlighting
Intermediate code (Assembler), Hex code viewer
Automatic completion, suggestions and parameter information
Installable library system
Project manager and source explorer to speed up the development process
Inbuilt help viewer
To-Do list editor
User configurable programmer and tools section

Prithvi is an Open Source Free Software project and it is based on MIT Open Source License. You can download Prithvi Development Studio from http://prithvi.sourceforge.net.

Simple ATMEL AVR – Programmer

2009-01-28T09:41:00.008+05:30

In this project we decide to implement simple ATMEL AVR microcontroller programmer for our hobby electronic purposes. We get ideas for this project from http://www.electronics-diy.com and http://www.societyofrobots.com. All the credits of this project go to them and creator of the ISP Programmer - Adam Dybkowski.

You can get complete circuit diagram from here

Entire project is based on the 7408 - Quad AND gate chip and it is possible to use any (CMOS/TTL) AND gate chip with this project. During the testing phase we use CD4071 and 7409 quad AND gate chips without any circuit modifications.

During the assembly process make sure to install proper heat-sink to the 7805 voltage regulator.

After constructing the circuit download and install ISP Programmer and follow these steps,

Open ISP Programmer software package and press "Setup" button to setup the programmer.
Select "AEC ISP" as a "ISP Cable Pinout" and press OK
Connect MCU to the programmer and power on the programmer
Select MCU type and oscillator (Crystal) frequency from the software
Press "Reset ON" button
Press "Read Signature" button

If the device and programmer is working properly ISP Programmer automatically detects the chip and flash memory configuration from chips signature bytes.

Now specify the hex file to ISP Programmer and press “Erase and Program All” button to start the programming process.

Note : During the testing/usage, some times we got “NOT KNOWN (FF, FF, FF)” as a device signature. If you get this error please check the following,

Programmer is connected to the computer and power on
MCU Crystal configuration

If ISP Programmer still produces an error, problem is in your MCU software. (Especially your MCU software produces output to the MISO and MOSI related ports.) Then disconnect programmer’s RESET connection from MCU and connect MCU’s RESET pin to the ground (0V) and continue your work. (Ignore the programmers RESET terminal)

This simple programmer support wide range of ATMEL ATtiny, ATmega and AT45x, AT89x and AT90x series MCUs.

Simple method to decompile (Microsoft HTML Help File) CHM files

2008-12-22T13:41:00.002+05:30

Microsoft compiled HTML help files are now commonly used in software applications and generally these files are opened using hh.exe (HTML Help) file in windows folder. The most important thing is, hh.exe have custom chm decompilation command. To use this option simple provide following parameters to hh.exe,

hh.exe –decompile

for example :

hh.exe -decompile E:\test\output E:\test\help_demo.chm

That’s all. Check the output directory for all HTML topics, Images and other related files.

9 Pin dot matrix printer using PIC16F84A

2008-11-07T07:55:00.006+05:30

In this project we design 9 pin Microsoft Windows NT compatible dot matrix printer using two PIC16F84A microcontrollers. Printer mechanism is based on old Commodore dot matrix printer. At the moment this device support for Microsoft Windows 2000 and XP operating systems.

Other most notable features of this implementation are,

Drive 18V - 9pin magnetic dot matrix head unit

Handle 12V paper feeder and head movement stepper motors

Support A4 and compatible page formats

System drives using 240V - 18V step-down transformer

Audible warning system

Low power consumption due to CMOS implementation

Works with Standard Printer Port

In this implementation we use Microsoft Windows Driver Development Kit (DDK) with Microsoft Visual C++ to create device driver for the system and use Delphi 7 to create front end application (printer maintenance – control panel applet). Both microcontrollers are programmed using MPLAB – ASM.

In this system we use 2 microcontrollers with 7MHz oscillators,

One PIC16F84A handles all incoming messages from LPT port and send status information to the port. This MCU also provide front end interface to the system (such as manual paper feeder switch, audible warning system, etc)

Second microcontroller handles printer head and paper feeder.

Other than PIC16F84s we use following semiconductors in this project,

Series of ULN2001 chips to interface system with printer head and stepper motors.

MC14066 as virtual switches

NE556 for audible warning system

LM317, LM7805, LM7812 power regulators

18DB05 Bridge rectifier module

During the test runs this printer produces an excellent results and only most notable limitation is its slow speed in printing. In future we plan to implement USB and Ethernet interfaces to this project.

Essential USB Specifications and Develop embedded systems with USB

2008-10-31T07:15:00.009+05:30

Universal Serial Bus (USB) allows peripherals and computers to interconnect using standard protocol and provide plug and play feature to the devices. At the moment there are 2 specifications available for USB they are,

USB 1.1 : In this specification data transfer rate is 12Mbps and 1.5Mbps.

USB 2.0 : Support data transfer rate up to 480Mbps.

Both these specifications support up to 127 devices and support for hot swapping (no need to power down to remove or connect the devices). In USB devices are categorized as a classes and each class represent the functionality that target device can provided to the host device. For example:

AUDIO : Audio and related systems

HID : Human Interface Devices. (E.g: Keyboard, Mouse, etc)

POWER: Devices related with the power such as UPS systems.

IrDA: Infrared devices.

There are 4 types of transfers take place over USB,

Control transfer : Used to configure the bus and devices on the bus.

Bulk transfer : Move data asynchronously over USB.

Isochronous transfer: Transfer time critical data and support for unidirectional transfers only.

Interrupt transfer: Used to retrieve data in regular intervals. (Generally from 1 to 255ms)

In a USB architecture data is transferred using packets and each packet contains synchronization byte, Packet ID (PID), contents and CRC (Cyclic redundancy check data) There are 4 packet types available in USB and they are,

Token Packets : 24bit packet that determine the type of a transfer that is take place over the bus.

Data Packet : Can transfer between 0 to 1023 bytes and also have 16bit CRC stage.

Handshaking Packet : Which is used to acknowledge the end to end data transfer.

Descriptor : Contain the device capabilities such as product identifier, manufacture code, class type, internal configuration, etc.

USB devices uses shielded four wires, cable to interconnect the devices. Data transfer is take place at D+ and D- (similar to RS422/485 specification) and other remaining 2 wires carrying power (+5V and 0V) to the device. D+ signal has a 15K pull-down resistor to the ground and D- has a 1.5K pull-up resistor to +3.6V power line.

Pin	Color	Function
1	Red	+5V
2	White	D-
3	Green	D+
4	Black	GND

In embedded systems there mainly two methods to implement USB interfaces,

Using standard bus interface: Most recommended devices are FT245, FT232 and USS820.

Using USB to SPI bridge: Most recommended device is ATMEL AT76C711 AVR microcontroller.

When designing embedded systems using USB we need to take special care about,

Noise : To prevent external noises designer need to add ferrite bead to the USB cable. Generally the value of the ferrite bead is depends on the total current required by the circuit.

Power Source : Need to provide well regulated power source to the device. Generally we use 7805 regulator to provide +5V to the USB interface and LM1086-3.3 to provide +3.3V power source to the system/device.

Double check the power lines (especially if you are working with FT245, FT232 and USS820 devices) and voltage ratings. Improper power connections and voltage levels may burn the chips and ports instantly.

Is Delphi for PHP successes ?

2008-10-31T07:07:00.005+05:30

I’m trying Delphi for PHP 2.0 in few days back and I'm get very frustrated about it because of its pour implementation and technologies. Some key failures in Delphi for PHP 2.0 are,

- IDE is very buggy and most of the times it produces "Access Violation" errors and IDE get confused. (In my computer Delphi 7 tries to debug it.)

- Help is very pour and incomplete.

- JavaScript and PHP integration is very complex and buggy. Most of the time JavaScript codes may not work in client side and it is heavily depends on the web browser.

- Some times it is necessary to deploy entire "VCL" directory to the web server otherwise some of the VCL components produces invalid outputs. (specially RichEdit and TrackBar components)

- MySQL integration is pour and buggy.

- Build-in Apache web server crash several times and because of that reason we may not be able to debug/run web application using IDE.

- Some times XML file (xml.php) generated by Form Designer may not compatible with VCL for PHP framework.

- Some of the controls have missing properties.

Actually most of these problems are not very critical (we can fix most of them at the work) and hopefully Qadram Software will fix these problems in there next releases but at the moment Delphi for PHP is not a wise investment for PHP rapid application developments (RAD) and I’m personally recommended to use PRADO framework (http://www.pradosoft.com/) instead of Delphi for PHP. PRADO have same features as Delphi for PHP. The only thing is it does not have drag-and-drop style IDE.

Compared with other web application development systems (IDEs) the concept of "Delphi for PHP" is an excellent and it provide complete web application development solution to the PHP, Delphi/C++Builder users, only thing is it need more maturity.

According to my observations Delphi for PHP is not a tool developed by CodeGear (former – Borland), it is developed by Qadram Software and the core of the system – "VCL for PHP" framework is available in Sourceforge.net as an open source free software project, (same as PRADO) so anyone can modify, fix errors or add features to that framework. VCL for PHP is distributed under the terms and conditions of GNU – LGPL (GNU Lesser General Public License), and its competitive framework PRADO is distributed under the BSD Licenses.

Note : If you are a Delphi/C++Builder developer it is highly recommended to use PRADO because it’s naming standards and execution patterns are more similar to Delphi VCL.

Design USB Devices and interface them using Delphi

2008-10-03T13:44:00.007+05:30

According to my experiences USB devices are bit complicated to design and writing software (drivers and support applications) for USB devices are time consuming and complex process.

Most recommended (and easiest) method to design hardware interface for USB port is using Future Device Technologies FT245 or FT232 chips. At the moment both these chips support for USB 2.0 and have excellent set of APIs.

To test the performance of this device I implement some experimental version of PC oscilloscope using FT245 USB Interface, AD7575 ADC, LF347 Op-amp, 4069 Hex Inverter and array of AM7205 FIFOs. Application program is design using Delphi 7 and it is totally based on FTDI Delphi APIs. This test system is worked perfectly in Windows XP and Windows 2003 systems during my test runs and produce excellent results.

I choose FT245 for this design because it has 8 parallel input interfaces and this is perfectly matched with AD7575 ADC. (AD7575 also have 8 parallel outputs) I use 2705 FIFOs to capture the maximum number of samples.

So implementing USB system is not a big problem now, we may use

FT245 Parallel USB FIFO or,
FT232 Serial USB FIFO

Both these chips have APIs in C++, Delphi, Visual Basic, etc. I’m choosing Delphi because of its performance, features and familiarity and I’m also use FT245 API with C++Builder 6, 2006 and Delphi 5, 6 and Delphi 2007 without any problem.

There are several interesting features available in FT245/232 chips which include,

Support for suspend mode

Several power configuration (USB self powered, external powered options)

Interface EEPROM with device descriptor.

Operate with standard +5V power supply

Higher data transfer rate (up to 15Mbps)

FT245/232 generally operates with +5V and all I/O ports support standard logic voltage levels so we can interface FT245/232 with any standard digital system easily and I’m also use FT245 with PIC and ATMEL microcontrollers without any problem.

Only problem in FT245/232 is its SMD package, because of this reason it is bit difficult to use this chip with standard project boards/prototype boards.

About Thoppigala 3D Computer Game

2008-07-08T09:19:00.006+05:30

Thoppigala is a computer game developed by Vectronics and according to my observations it is developed using Game Creators FPS Creator. I have demonstration version of Thoppigala game and it is totally based on FPS Creator models and FPSC Model Pack 5. The vendor (Vectronics) do model’s texturing part only. Demonstration mission available in this release (file version 1.0.0.0) is based on the FPSC sample mission and it’s level designing is in very poor stages.

In this game, player use Tommy Gun (Thompson Submachine Gun) for it’s operations, but the problem is according to my knowledge Sri Lanka Army may never use Tommy guns for there operations and it is widely used in World War II and currently it is not in use. FPSC model pack 5 contains good weapon collection and I don’t know why designers may not use them for these missions.

This game have lot of other problems, most notable problems are,

Enemy AI : During the attacks, and all the others just choose some random direction to run in, and doesn't stop at walls. This may be able to fix using script modification.

All the enemy entities are act in very artificial way. This is a main problem in FPSC, but it is possible to fix this using source code supplied by game creators.

Game may not work with some video drivers. (for example in nVidia FX5200 – version 9.1.3.1.)

Game voices are not very attractive and in poor quality.

Some of the debugging features may not disabled by the Vectronics, such as "Tab" key.

Game Creators release lots of model packs for this tool, (and lots of free models and scripts are available in web too) using these resources they may be able to shape up there product.

This game "Thoppigala" is become more attractive if developer choose a correct engine like "Reality Factory", "Jet3D" (this is also a non/less-programmable game engine) FPSC is good for guys who don’t know programming or 3D modeling. This is a commercial game, so developer need to think about its game engine again. Most people may not use FPSC for there games because of it’s poor quality (for more information check DevMasters – FPSC Page)

In this game author try to do something new (and I’m personally appreciate his/her vision in this game), but (s)he use wrong tools and technologies to implement this game.

Simple Variable Zener Diode

2008-07-06T07:58:00.001+05:30

There are several variable zener diodes available in IC market, but in Sri Lanka it is difficult to obtain variable zener diodes. (For example LM431) So I build this circuit to get the functionality of Variable Zener diode. This circuit is based on two transistors and for Q1 you can use any general purpose NPN transistor and for Q2 use any general purpose PNP transistor.

Using this circuit it is possible to get 3V to 25V (400mW) output. I use this circuit for one of my SMPS project (as a replacement for LM431) and it produces an excellent results.

Notable 3D Game Engines – Part1

2008-06-20T12:19:00.001+05:30

This series contains list of game engines explore by me during the implementation of our STF game engine,

Panda3D – Open source game engine (use BSD license) mainly based on C++ and Python. Engine is smart and has narrow learning curve. We got most of the ideas to our project from this game engine.

http://panda3d.org/

Torque Game Engine – One of the best and full featured game engine. I try to select this engine for our game “Special Task Force” but it is not success because of the license problem. (STF is an open source game project, so we need to release all the source codes with it, but TGE license may not allow this.) Compared with other commercial game engines TGE is low cost 3D game engine (US$150 per programmer) but it had some wider learning curve.

http://www.garagegames.com/pg/product/view.php?id=1

FPS Creator – Product from “the game creators”. Using FPSC anyone can create FPS (First Person Shooter) game without any coding. FPSC have drag and drop environment to create games but I notice several bugs in the system. One of the Sri Lankan computer game “TOPIGALA” is build using this software package. FPSC is developed using Dark Basic and al the source codes are available in FPSC Home page. (But do not try to build this game engine using released source code, if you build FPSC from released source code then some of the features like bots collection detection may not work properly, to work them properly you need to install several add-ons to Dark Basic compiler)

http://www.fpscreator.com/

Genesis3D – Another 3D Game engine for Windows platform, it similar to Doom Engine. There are several game titles are available with this game engine and most notable one is “Special Force from Lebanon based paramilitary group”. The engine is fairly OK but it had some wider learning curve. This game engine is free and source code is available to download.

http://www.genesis3d.com/

Truevision 3D – TV3D is one of the excellent game engine I have seen. TV3D is easy to learn and support for Delphi, C++, VB, C# and VB.NET. TV3D SDK is available to download and the engine is well documented. PlanetX is a suitable world editor for this engine and it is released as a commercial product.

http://www.truevision3d.com/

Special Task Force Game – System Implementation

2008-06-14T21:23:00.000+05:30

Implementation of our new 3D computer game “Special Task Force” has been started and all the development related news are available at Special Task Force Developers Center (STFDC) at http://stfgame.wiki.sourceforge.net/.

All the applications (including libraries) in this project are published according to the specifications of GNU GPL. All the documentations, guides and text files are protected using GNU FDL, and all the models, images, voice files and music files are protected using Creative Commons License.

Home-produced USB Sound Card

2008-06-10T11:30:00.004+05:30

In this project I’m build USB sound card using single chip and it produce good audio output and compatible with Windows 9x operating systems and Windows NT family operating systems (I am not tested this circuit with Windows Vista and chip manufacturer say it is worked with Mac OS also) This is a plug and Play device and device driver is not required. Special feature of this sound card is its built-in HID controller. Using this HID controller user may be able to control Windows Volume control using 3 buttons located on the sound card. These buttons are used for Volume Up, Volume Down and for Audio Mute.

This device is based on Burr-Brown’s PCM2904 USB CODEC chip and it produces stereo output. PCM2904 operates using USB power (self powered) and external power adapter is not required.

I think this device is ideal for USB headphones or mini-speaker modules. My implementation is 10x9 cm. I spend Sri Lankan Rs. 1500 for this circuit.

13W x 4 Audio Amplifier with Surround Sounds

2008-06-07T08:04:00.005+05:30

This is my new audio power amplifier which is based on TDA8511 power amplifier IC. According to the datasheet this IC produces 13W per channel (with 2R load) and single TDA8511 chip contain 4 inputs and outputs.

Other than TDA8511 this amplifier use TA8184 for tone controls and LA2610 for surround sound processing.

To obtain the high sound quality and good separation I use separate amplifier module for each tweeter and woofer in both left and right channels. (That’s why I’m select TDA8511 for this project)

For the test run I couple this amplifier with my JVC DVD Player and it produces extreme high quality audio output.

Front Panel controls available in this amplifier are,

Volume
Bass
Treble
Balance
Surround Sound On/Off
Loudness Switch
Power On/Off

Some of the calculated technical specifications are,

Output Power : 13W x 4
Supply Voltage : 15V Single Rail
Total Harmonic Distortion : 1%
Bass Control Range : -12.5dB to +12.5dB
Treble Control Range : -12.5dB to +12.5dB

Open Source 3D First Person Shooter – Special Task Force

2008-06-06T21:33:00.001+05:30

We start new open source game project known as “Special Task Force”. It is a FOSS project and hosted at sourceforge.net. At the moment project is in planning stages. Some of the finalized features of this game are,

Based on OpenGL 2.0 Graphic Technologies.
Support Python 2.3 Scripting
Use BASS sound system for audio
Use ODE (Open Dynamics Engine) for game physics
Support Multiple weapon configurations
Support for downloadable missions
Implement using Borland Delphi and C++Builder

Still we are collecting information and getting ready for the implementation, Source code implementations are planned to start at the mid of June 2008. For more information please checkout http://sourceforge.net/projects/stfgame

My PIC16F73 base Digital Alarm Clock

2008-06-06T20:42:00.006+05:30

In last two months I developed some electronic devices using Microchip microcontrollers. First device is an electronic alarm clock using PIC16F73 and 4060 timer chip. This clock has 2 programmable alarms and it is working successfully in last two months continually.

I design this alarm clock using CMOS chips; due to the fact that power consumption is very low and may be able to operate with 3 penlight batteries. At the moment this device is working with mains power (230V AC) and has battery backup facility.

Size of the entire device is 11x11x4 cm.

As shown by the photograph device have 3 push buttons and 1 SPDT slide switch. These push buttons are used for,

Alarm Mute / Mode Selection
Hour Set
Minutes Set

SPDT Slider is use to select “Clock Run” and “Alarm Setup” modes.

This system use following chips for its operation,

4060 – Act as an oscillator and divider
4027 – Toggle clock single and to control 1Hz clock pulse.
4017 – Divide by 10 counter
PIC16F73 – Main control system
7805 - +5V regulator

Microcontroller is programmed using MPASM and it is the most critical part of the implementation. (I spend 1 week for this)

I got seven segment display module from old satellite receiver and to build the entire system I spend Sri Lankan Rs. 500.00.

Welcome to My Web Log

2008-06-06T19:19:00.000+05:30

Hello, welcome to my web log, in this web log I mostly discusses about technical subjects related to computer programming, digital electronic circuits (specially related with microcontrollers and control systems) and some mechanical implementations.

This is my personal web log, so some non-technical stuff are possible to appear in this space.