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The electronic and computer related projects described below are 100% free. Copying, distributing and using them is fully permitted. Any references to pieces of work done by others are clearly stated. Comments and remarks may be sent to the author: jarek.paluszynski[at]e-ware.pl
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Computers & microprocessors
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Microprocessor LED clock with alarm
This article describes how to build a clock using a popular Atmel 89C2051 microcontroller and some simple HC-TTL chips. The current time is displayed in a pseudo-analog way, using 4 seven-segment LED displays (hours and minutes) and 120 LEDs on the clock dial's perimeter (seconds). The alarm and time is set by 2 push-buttons built into the power supply. A simple program in '51 assembler manages all the clocks functions. A stable +5V/1A power source is also described.
TRITON jukebox
This project is definitely the largest in terms of capacity. Triton is a jukebox integrating a PC-based MP3 player and a double subwoofer. A more detailed list of elements includes: a PC (P133, 16MB RAM, 17GB HDD), a twin subwoofer box (2 x 400W PMPO), an stereo amplifier (2 x TDA7294 - 2 x 180W) with a low-pass filter, a 450W power supply and several control systems (keyboard, keyboard control circuit, analog multiplexer, computer cooling system). A project of the subwoofer wooden chassis is also included. Not yet translated!
Thermometer with PIC16F84
The project described here is a digital thermometer built with the PIC16F84 microcontroller. Temperature measurement is achieved indirectly, by measuring the time a capacitor discharges through a thermistor. The current temperature, along with a graphical diagram of the temperatures in the past hours, is displayed on a 1x24 LCD panel.
LCD CPU-load meter
A system measuring CPU load and displaying it on an external LCD panel connected to the parallel port. To accomplish this project only one major electrical component is needed, an alphanumeric LCD display. All control logic is coded in a Windows application written in Delphi. Additionally, a graphical diagram of past CPU load is displayed on the LCD.
PC infrared modem
The project described here is an infrared modulator-demodulator (modem) meant to work with the PC parallel port. The original hardware is Zbigniew Raabe's project published in the 10/1999 issue of "Elektronika dla Wszystkich". The circuit allows 36kHz infrared transmission in both directions, to and from the computer. The only missing part is the software, and here the fun begins...
Wireless infrared PC keyboard
A simple wireless keyboard for the PC involving infrared tranmission from the keyboard to the computer. Microcontroller AT89C2051 as the transmitter and receiver. Not yet translated!
PIC programmer
A simple programmer for PIC microcontrollers (series 12CXXX, 16CXXX) and serial EEPROMs (series 24CXX). The electrical circuit and software is based on Jens Dyekjær Madsen's programmer (
http://www.jdm.homepage.dk).
Audio & RTV
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Car amplifier 4x22W
A inexpensive car amplfier with simple design, but very good parameters. Maximal output power can reach 4x22W. The heart of the amplfier are two Toshiba TA8210 chips, each driving two speakers. The TDA1524 integrated circuit from SGS-Thomsom is the preamplifier, allowing wide regulation of tone, gain, and balance. Additionally, an LM317 voltage regulator is included, sourcing stabilized 3V, 5V, 9V, and 12V power. This allows external sound sources (like CD-players, MP3-players etc.), to be powered directly from the amplifier.
The simplest amplifier
A very easy to build power amplifier based on the LM386 chip. This chip, along with a few resistors and capacitors, is all that is required. Insignificant input current and a wide range of power voltages makes this circuit ideal for battery-powered applications.
PC Preamplifier
A simple NE5532 stereo preamplifier assembled on a PC back flap. A simple and cheap circuit (~$2), which proved itself useful as a guitar preamp.
Laboratory devices
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Experimental 12V/6A power supply
This project involves building an experimental 12V stabilized power supply capable of giving quite high currents (6A). It is experimental because stabilization is achieved in an untypical way (six 7812 stabilizers in parallel) and because the device has an internal ammeter (with 3 digit LED reading) and an electronic switch.
Household electronics
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Battery tester
A simple tester for AA type 1.25V and 1.5V batteries based on an LM3914 chip and a LED line.
Software
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WWW counter statistics
The problem discussed here follows. We have a counter on our HTML page, which writes the number of hits to a file. We want to see how the number of visitors to this page evolved in time, generally to draw a diagram of hits in the time domain. This is the description of a simple system, which allows to run such statistics. CGI script + Shell script + Windows visualization application (C++ Builder).
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Last modification: 2004-03-31
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