Inductive Loop Detector - Project published
Inductive Loop Detector works by detecting an inductance change in wire loop (coil) that is buried in road. It does that by measuring the frequency of the internal oscillator which powers the mentioned coil. When a metallic object moves over the coil it changes its inductance and that in turn changes the oscillator frequency which is measured by the microcontroller.
It is used for vehicle access control at door and barrier controls, for monitoring the occupancy and for vehicle counting in parking garages, traffic light installations and traffic controllers, direction and speed detection of vehicle traffic (if dual channel version is used), in car-wash plants, etc.
Nixie Tube Clock - Amy Time!
When Reboots saw an old General Electric battery charger, he thought it would make a great Nixie Clock enclosure. It is made of aluminium and front panel is home-built and etched in acid.
Electronics are built around ATmega48 microcontroller, DS32kHz 32.768kHz TCXO whose output is connected to TOSC1 input pin of microcontroller. Nixie tubes (IN-12) are driven by high-voltage shift-register (serial-in parallel-out) HV5622. High voltage generator for this project is built using good old MC34063A in step-up configuration.
Source: Engram Enterprises
How to make a 4-layer PCB [video]
The process of creating the printed circuit boards is very time consuming and has a lot of steps.
We all know how to make single and double layered PCBs (many of us made a 2-layer PCB with success at home) but this video goes into detailed factory steps in making a four layer PCB. It is very interesting to see how it is all done in factory in large scale.
Current projects and news
Since I didn't post anything for almost a year, it would be good idea to introduce you with some of my previous and current projects that I am working on.
Project 1: Vehicle Inductive Loop Detector. This device is used to detect presence of vehicles above the wire-loop buried in road. It took me few months to perfect this project and current version of this device is v2.1 (third).
Project 2: Word Clock v2. Front panel is now looking much better because I used a car tinting foil to darken not-illuminated letters. You can see the effect of this foil in the photos later. Electronics are also replaced, new PCBs were designed and factory made.
Project 3: Vehicle-activated sign - a road sign that displays current vehicle's speed by using Doppler radar technology and 7-segment display. This project is currently on hold until Project 4 is done.
Project 4: This project doesn't have an official name yet, but it is used to control home appliances over the Internet.
Word Clock - published
I have been seeing these "Word Clocks" all over the internet for the past few years, but they never really impressed me much. Mostly because there is nothing special about them (from the electronics point of view) but after seeing QlockTwo made by Biegert&Funk I simply couldn't resist making one that looks that nice.
But of course, in my local language. Aside from different language, I wanted it to be able to display full time - every minute of an hour - so I ended up using 248 white LEDs. To keep that stealthy look I used two capacitive touch sensors under the glass (near left and right LED dots) as buttons for the user-input.
Electronic gear shifter for bicycle
To change gears on your bicycle via button would be an awesome feature, something like manumatic (triptronic) transmission in cars.
Nabil successfully hacked his bicycle and added a servo motor to rear derailleur which now allows him to shift gears via two buttons. Servo is controlled with Arduino board and two buttons that change gears are located in one of the bike handlebars.
Hack involved removing a spring from rear derailleur mechanism to make shifting easier for the small servo motor.
Speed measurement using webcam
If you ever wanted to know the speed of moving vehicles in your neighborhood, well, now there is a cheap and simple solution to find that out. It turns out that it is enough to point your webcam to the street and start the appropriate software!
In order to measure the speed we need two parameters: time and distance traveled. Here we have a solution that uses web camera and Python script to figure out both of those parameters by finding difference in pixels of consequent images and calculate the speed of moving object that is detected as moving.
Be sure to read the entire article on the next page and to take look at the Python script that does the job!
Source: John - More Fun Science
Sip and Puff iPod Dock Controller
By definition, Sip and Puff technology is a method used to send signals to devices using air pressure by sipping (inhaling) or puffing (exhaling) on a tube.
Detecting positive and negative air pressures in that tube can be done by using an air pressure sensor, the resulting pressure can be read from a sensor with ADC input pin of a microcontroller where in turn the microcontroller can control some device. In this case, that device is an iPod and the project name is Sip-n-Puff Arduino Shield.
Be sure to check the video where the author explains this method using Arduino in details.
Source: Bob Johnson