Many times you need to remotely control a relay, electrovalve or some other electronic or electromechanical device, and many times wirelessly. With XBee modules things become very easy. Very versatile and having small dimensions it is easy to add it to your projects.
In this demonstration the modules are set to wirelessly control two types of relays, standard and latched. To achieve this you will need to configure the analog inputs of the Xbee to digital I/O. In the given schematics the standard relay is driven by a general purpose NPN transistor T1. Some relays already have the protection diode incorporated, if not you will need to use D1 as shown.
The latch relay is driven by a hex inverter IC connected as a buffer. Each inverter changes the logic level from high to low and from low to high so you must cascade two inverters to preserve the logic level. This type of relay is activated by pulses so it needs a small amount of current. Even so the output capability of a single inverter might not be enough so the remaining inverters are connected in parallel.
On the transmitter side you have two push buttons connected between ground and the digital I/O ports of the XBee. There is no need for pull-up resistors because this is done internally in the Xbee.
This demonstration has lots of practical applications. You can connect almost anything to those relays or use the digital output of the module with a buffer to control other devices or transmit information.
“Operator?! I need an exit!” I bet if iPhone existed when they shot The Matrix they would’ve used it. It’s a great device and can really get you on antidepressants when it gets damaged somehow. There are however some problems that you can fix yourself, for example a cracked front panel. The iPhone is a little more difficult than regular phones to open so you will need some tools but nothing very exotic.
Since you will be dealing with small and sensitive mechanical and electronic parts you must be very careful and meticulous. Specially when you are using metallic tools that can scratch or slip and damage some other component. If you tried to open the older iPhone you will be pleased to know the newer iPhone 3G is more friendly in that matter. The display can now be detached from the front panel with little care. The front panel glass is glued to the rest of the case, but the glue gets soft if you heat it.
It is very well suggested to put the screws and other parts that come off on some scotch tape so you don’t lose them. A magnet also works very well for screws.
With some care the results can be excellent and your iPhone will be back in shape. So get to work and enjoy.
The heart of each CNC machine, and many more automated systems for that matter, is the stepper motor. This motor allows for precise control over the spin of it’s rotor by applying pulses to the stepper’s coils. This project explains how to build a cheap and simple controller for such a motor, and it does that step by step, hehe.
The components used come from an old scanner. You need a stepper, a ULN2003 IC and the two steel rods on which the scanning lamp slides. The ULN2003 has seven high current darlington transistors and four of them will be used to drive the coils of the stepper motor. The control pulses will be given by a PC software through the parallel port. Nowadays PC’s don’t have the parallel port anymore so look for an old computer. Parallel port is also called printer port on some machines.
Pins 2 to 9 of the DB25 parallel port are assigned to Data bits, in our case the first four bits are of interest. The logic words that come out on the data bus of the parallel port are given by a pc software, Turbo CNC. Of course this can be taken into a much more developed project. As presented, if a bit is set to “1″ then the associated coil gets one pulse because the ULN2003′s darlingtons act as inverters.
The project provides a test program to see your controller in action. For this you will need to use those metal rods to form a testing rig. Fairly simple thing if you know your way with a screwdriver.
A PCB layout and information for a three axis controller is provided as well. With the three axis all output pins from the parallel port are used and three ULN2003 ICs but you could use only two because each one has seven darlingtons under the hood.
It is really a good project, educational as well as practical if you need a low cost controller, and steppers can be found anywhere today… look inside your cd-player for example. So go for it!
CNC Controller made from scanner components: [Link]
“Bilbo, look out for the Dragon!” cried Frodo. “Dragon? Nonsense! There hasn’t been a Dragon around here for a thousand years!” said Bilbo… but little did he know what some people are building in their dungeons. Presenting “Puff” the fire fighter Dragon. I bet Smokey the Bear will lose his job soon, as forest fire prevention mascot.
The Dragon, once it finds a fire, has it’s eyes fixed on it, closes in and puts the fire away with his breath. He he I know what your thinking but it’s napalm glands are only active in angry mode. If he fails to put down the fire after two sweeps, he backs away to save his skin.
This project is based on an Arduino processor and MotorShield. Two gear motors with 224:1 ratios and PolyMorph axle extensions are used for movement. Puff moves his head to left and right with the help of a servo and does that in a 60-120 degree range. His “eyes” are two light sensing resistors, each one placed at the end of a heat shrinking tube so that localization of the fire is more precise. Also you must isolate the back of the resistors as well, for the same reason.
Once his eyes are fixed on the fire his breath comes from a little fan and it’s motor. A Sharp IR sensor provides cliff and obstacle detection. You will have to angle it so that it’s focus point falls at 10cm away on the floor. The Dragon’s head is made of paper that you can print with your desired model.
A cool project for all those into the electro music. Here is something that even Jean Michel Jarre would want… an infrared Theremin-like musical instrument! Notes are vibrating from speakers just by moving your hands in thin air. One hand controls the note played and the other hand controls the octave. The difference is that the sensors are not antennas but two IR devices from Sharp, the GP2D120.
Notes are predefined, so unlike a Theremin, it’s pretty easy to play it. The instrument, named Squaremin, can only produce flat notes from the C major scale, so only C,D,E,F,G,A,B within 7 octaves. However you can change these notes to your desired scale, all you need to do is to define new notes by changing the period of the pulse in the source code. The microcontroller used is the ATmega168.
The operation of the instrument is given by the two IR sensors. These sensors can determine how close an object is to them by using triangulation. A pulse of IR light is emitted and if an object is in the way it reflects the light back to the sensor. A CCD array within the sensor receives the reflected light and determines the angle of this reflection. If the angle is wide it means the object is far and if the angle is narrow it means the object is close.
Therefore depending on the distance your hand is from the sensors, you change the notes and the octaves. The Squaremin has an internal audio amplifier with a small speaker but you can easily add a line out connector so you can hook the instrument to a mixer for example. Also it provides a little light show as it changes color with every note you play, again reminding of the awesome J.M. Jarre concerts.
All in all, although the spectral composition of each note is not that rich, this principle can be applied into a real instrument project that instead of microcontroller generated sounds plays real samples.
