Hardware random number generator on USB
This is one cool source of true randomness.
Device featuring a real sand timer, servo rotating mechanism, optical beam for detecting randomness of sand particles falling through (but not sand droppings) is a really cool device for generating random numbers. Anyway, I will not get into the discussion of how random results of this random generator are, just watch the video after the break and check out the results at the project page (the source) link below the video.
Source: A. Peter Allan
LCD tutorial with Atmel
This is a two-part tutorial on how to run character LCD display on Atmel ATmega8 microcontroller.
Display is HD44780 driver based and both methods of using it: 4-bit and 8-bit interface are covered in this tutorial. Any other microcontroller of mega series can be used and the firmware is based on alank2's C LCD library.
Source: Daniel F Garcia
Simplex Repeater for two-way radios
For longer range of two-way radios using an external antenna is in most cases just enough. In cases where it is not possible or simply not enough (or not allowed) a repeater is used. Repeater is nothing new to amateur radio (HAM) operators and they all know that it uses different transmitting and receiving frequencies. Setting up the radio to repeater-mode is no big deal but with FRS radios repeater-mode is not implemented at all.
Because of this, using FRS radios on classic repeaters is not possible (or very hard). Solution is to use a Simplex Repeater. Simplex Repeater is, again, not a big deal with amateur operators but for FRS users it might be. This repeater receives your signal on one channel, records it internally and re-emits it on the same channel once you stopped transmitting. These are also called "Parrot Repeaters".
Source: Petri Tarkiainen
Automatic coming/leaving home light published
Those days when I come home at night and strait into the darkness are finally over.
This is a very practical device and I built it so that it is a module to my Dual Channel IR Remote Control. Because of that I ended up with a definite overkill of what is supposed to be a simple switch with a timer when I open/close my door. Anyway, it is modular+wireless and that's what I like.
Firmware source-code included!
Additional domain name for elektronika.ba
No, domain name has not changed.
Happy surfing and for all those working people out there, have a Happy forthcoming International Workers' Day!
Dual channel IR remote control published
This project is very similar to previous one: IR light dimmer v1. The reason for building this device is primarily because incandescent light bulbs are being widely replaced with fluorescent power-saving ones.
So, the differences between dimmer and this device are that it has two channels, it can't be used for light dimming and it can control those power saving fluo-bulbs which have internal electronics/converters. The controlling element is solid state relay (SSR) which consists of opto-triac MOC3043 (MOC3042) and a triac (ie.: BTA16, BTA08, ...). This combination enables us to turn ON/OFF all kinds of appliances (motors, lights, heaters, boilers, PC...).
Geiger Counter with Arduino and LCD
If you ever needed a Geiger Counter but couldn't find one, why not build it yourself? Geiger Counter is a very simple device but having in mind that it requires very high voltages for operation it might get tricky to interface it to a microcontroller and even have it operating on batteries.
Here is a Geiger Counter project that is hand-held, operates on batteries, has LCD display for visual and piezo beeper for audible particle detection notification. It uses Arduino for digital processing and for the detecting part - SSBM-20 GM tube is used. Anyone trying to build this device should bare in mind that it uses high voltages (around 500V) that are generated with a simple boost converter with NE555.
I also found an interesting video introduction to a Geiger Counter device so make sure you don't miss it.
Police in every vehicle
If you get off at high speed pursuits involving a flashing police vehicle behind you, this one is for you. Or should I say: if you get in trouble very often for speeding...
Michael from Project Lab has built this smart device that mimics police car pulling you over whenever you are speeding. It features: EM-406a GPS receiver, ATmega328 microcontroller with Arduino bootloader and some red&blue LEDs. There are also two white LEDs which represent headlights of a police car for even more realistic feel. When everything is put together, a predefined "zones" with speed limits are compared every second with the actual speed of the vehicle. When the actual speed is over the limit a police lights engage to alert you to slow down. If the lights don't turn off after you slow down - you better stop because you are probably getting pulled over by the real police.
Source: Project Lab