A very interesting project showing you how to turn on and off the power from your mains outlet through computer network. It is very well documented and very useful. Basically you could turn on or off any device from any location as long as you can connect to your network.
The on/off switching will be done by an Olimex AVR/IO board. This board is equipped with an ATmega16 microcontroller (with no initial software loaded), four low-voltage inputs, a serial interface and four 5A/250V SPDT relays. These relays can be controlled by serial, by the four inputs or both depending on the code you will write for the microcontroller. So it is a very versatile board and only your imagination is the boundary of it’s utility.
The four low-voltage inputs are optocoupler isolated so this input can accept signals with different ground. Also these inputs are very helpful if you want to use a wireless module like the XBee. A PNP transistor is used to drive these inputs without any trouble.
Each relay provides connections for both normally open and normally closed positions. The relay will be placed between the hot wire that comes from wall and the hot wire that goes into the outlet. This way it will open or close the circuit on your command. Be careful however of the power consumption of the device you plug in the outlet. The relays are rated at 5A but they can be changed if your requirements ask for it.
The network controller is the Atmel NGW100 and will allow you to control the Olimex board through the network. It has two ethernet ports, lots of GPIO ports and Linux with TCP/IP installed. Control of the GPIO ports can be a little tricky with the NGW100 but you will find the scripts in the project.
The next thing is to connect the NGW100 to the network. Once that is done you can access the NGW100 through the network and execute the scripts according to your desired action.
Controlling Mains Power Through Network: [Link] – [Via]
Interesting weekend project for those who still remember the awesome game or just to awake in your kids the knack for electronics here is the Space Invaders Button.
Fairly easy build, having the ATmega16P at the heart controlling an 8×8 bicolor LED matrix which will display animations of the gameâ€™s spaceships. Principle of operation is simple, the rows of the matrix are driven by a npn transistor in an emitter follower configuration.
This transistor provides the boost of current needed when two or more leds from the same row are on. The state of the ports driving these transistors is set on â€śhighâ€ť logic level. You can now command each LED to light the color you want by setting the assigned port to “0”.
The ATmega16P will draw a small amount of current and can be powered by a 3V cell battery. The PCB is of small dimensions since SMT components are used, it’s even smaller than the LED matrix and thus hides nicely behind it.
It’s an easy project with little chance of failing and offers a nice lesson on how to handle the ports of your microcontroller. If you are doing this just for fun and you donâ€™t care about dimension than the SMT can be avoided so that you can use the controller for other projects.
Space Invaders on a LED matrix: [Link]
The term POV is for Persistance of Vision, I don’t want to bore you with definitions or explications, just look at the next picture:
The project is very simple, first of all because this type of display is the easiest to build, and because the author made it only for three letters, this way everybody can understand the basic principles and extend the functionalities.
The source code should be optimized and added some position sensing to synchronize the image. The schematic isn’t available but form the source code is easy to reverse engineer, since each led is driven from one micro controller pin.
If you add an accelerometer then you can stabilize the image even when rotating by hand, off course the overall weight must be reduced. With some wireless link you could even refresh the image dynamically.
Simple handheld POV: [via] [link]
The goal was to design a home made LED Display that can be expanded to bigger sizes with minimal costs. Unlike other systems, on this one the image gets scanned mechanically and the image is created by using the POV effect (persistence of vision). There are 32 RGB LED used in the project but you can easily increase the number of LED’s. The author attached the system to a spinning fan, and the images started to appear.
ATmega16 RGB LED Display: [Download Project] – [View Project PDF]
A master-controller board and three stepper motor driver boards drive this well-designed PCB drill machine. There are four single-sided boards each featuring an ATmega16/32 microcontroller. The master controller initiates and controls all communication. The result ? you drill your PCB’s precisely at the right spot.
3 axis PCB Drill: [Download Project] – [View Project PDF]