Persistence of vision (POV) is a phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina.
Image Credit: Wikipedia
Recently, a Maker by the name of Vishalapr created an inexpensive POV display using an Atmel ATtiny85 microcontroller (MCU) paired with a DC motor.
Aside from the Atmel-based ATtiny85 and DC motor, additional key components include:
5 LEDs
3V coin cell
Coin cell holder
USB header (a normal USB cord would do)
A case/enclosure to keep the motor in
A piece of wood or cardboard for the LED bar
IC holder
Protoboard
Jumper cables
Vishalapr kicks off the project by making a simple LED board out of cardboard/wood. He then connects the ATtiny85 MCU and the motor/power supply, placing the various components in an enclosure.
Next up? Installing support for the ATtiny series and programming the ATtiny85.
“So now that you have built a 5 LED POV Display, why not try something bigger? How about a 10 LED POV Display with an Arduino instead of an ATTiny85 (supports only 5 outputs),” Vishalapr added.
“We can also make this wall mountable by adding a small hole through which you can hang it on a nail firmly. Using some tricolor LEDs and more pins, we can give out a multicolored display.”
A Maker by the name of Yu-Ning Lin has designed an Arduino-powered quilting platform that combines the mechanics of a sewing machine with CNC technology.
“[It] uses four stepper motors to control the x-axis, y-axis, the bobbin case and the threading. The bed moves in x and y direction, while the threading moves up and down.”
SparkFun theragrip thermal tape Linear motion shaft (2)
Linear bearing for 3D printer (4)
According to Yu-Ning, most of the parts were laser-cut, with various pieces first modeled in Rhino.
“Instead of fabricating all mechanical parts of the sewing machine, I took the existing parts of a mini sewing machine and reassembled them for my Arduino Quilting Machine,” Yu-Ning added.
“The only custom parts are the shuttle hook cover, shuttle race, bobbin case and the entire needle bar.”
As 3DPrint’s Monica Aderholt notes, one of the major ways Gelstronic was able to keep the price so low was by recycling old computer and printer parts.
“Tarkun obtained four stepper motors from old DVD and Blu-ray drives, a power supply from an old PC, a NEMA 17-like stepper motor from an old printer and a modified gear from an old Hewlett Packard printer, which was used for the bowden extruder,” Aderholt explains.
“Of course, he had to use a bunch of screws, washers, nuts, wires, etc., but these were things that he and a lot of people would have lying around in their garages. For the frame of the printer, he did cheat slightly, and used some aluminum sheet metal that he had lying around. However, he points out that this could be replaced with wood.”
All told, Tarken ended up spending only 49 Euros, or approximately $67 on all purchased items, which isn’t bad for a 3D printer that offers the following features:
Fused deposition modeling ABS/PLA
Heat bed
Use of open source firmware – a modified version of Tonokip
“I’ve always loved watches; not only are they aesthetic and beautiful, but they are functional, precise and useful. An elegant fusion between engineering and art; two normally opposed perspectives, now joined in harmonic unison,” N.fletch explained in a recent Instructables post.
“However, all technologies like the dial-up internet, the CVT monitor and the abacus, inevitably will become relics of our past with the advent of advancing technology and have since become less pragmatic for the typical person to own. Unlike these archaic technologies, the wrist watch still thrives on the wrists of many, standing forever as a testament to one of mankind’s greatest inventions: the measurement of time.”
Aside from Atmel’s ATmega328P, key ChronosMEGA specs include binary time encoding (via 10 Blue 1206 LEDs), a slew of buttons to control time, sleep mode and display, a 32.768kHz external crystal and an 8MHz internal clock source.
Additional key features?
Micro-USB and charge management controller (for 400mAh Li-ion battery)
Draws 4uA in its Deep Sleep mode to last up to 11 years on a single charge
Battery indicator 0603 LED
Boost TI switching regulator for power regulation
Low loss PowerPath controller IC for power source selection
Total form factor of 10mm x 40mm x 53mm
Custom 3D designed case cast in pure polished silver
Genuine crocodile leather watch band
As you can see in the videos above, the layout of the watch configured in a circular array of 10 LEDs. Four of the LEDs account for hours, while six of the LEDs account for minutes.
“The LEDs count in binary to display the time on the watch face. By utilizing a combination of the 10 LEDs, the watch can display any possible time accurate to the minute,” N.fletch continued.
“This is a very clean and elegant way to display time. I also really like this technique because of its esoteric and mysterious nature.”
In terms of the MCU, the ATmega328P is wired in a straight-forward manner, connected to power and ground, with a pull up resistor on the RESET pin. Essentially, the AVR is tasked with driving all the LEDs from its GPIO, although one of the MCU’s AVR’s ADC pin is connected to the battery to detect the voltage level. As such, the watch is equipped with a small red status LED to indicate when battery power is low.
“The AVR has a 32.768 kHz crystal wired to its XTAL pins. It uses the 32.768 kHz crystal to drive its Timer2 module asynchronously for counting the seconds, [while] its internal 1MHz RC clock drives the SW,” N.fletch added.
“32.768 kHz is a very common frequency to drive Real Time Clock (RTC) systems because 32,768 in decimal is equal to 8000 in hex. Therefore, 32,768 can be evenly divided by multiple powers of 2 including 1024. Dividing 32,768 by 1024 yields 32, so configuring the timer to count to 32 with a 1024 pre-scaler will equal an exact second.”
“[The] workout shirt utilizes the MP3 player and an accelerometer to detect whether or not the wearer is moving. If so, it plays his or her music. The goal of the system is to promote an active lifestyle for wearers,” BBrodsky wrote in a recent Instructables post.
“The price of our system ranges between $60 and $100 based on parts used, the cost of the shirt, etc. It is affordable, easy to understand and create and will help promote healthiness and physical activity in society.”
Aside from the LilyPad MP3 player, key project components include:
LilyPad accelerometer
RGB rotary encoder
3.7V Lipo (lithium ion) battery
Micro SD card
Headphones or speakers
Conductive thread and a sewing needle
Soldering iron
Solder coil
Alligator clips (for testing the circuitry before sewing)
Rainbow LEDs (optional)
Vibration board (optional)
Button (optional)
On/off switch (optional)
Extra fabric and card stock (optional)
BBrodsky kicks off his Instructables by providing a brief overview of the MP3-equipped workout shirt.
“[The] system uses the accelerometer to sense motion, communicating the detected motion (or lack thereof) to the MP3 player. The MP3 player then runs the corresponding functions based on the values it receives from the accelerometer. The RGB rotary encoder is used as a visual that displays different colors (blue or green) based on what function is being executed,” he explained.
“Once the system is completed and integrated with the shirt, the device should be ready to use. Keeping the device plugged in using via USB to a laptop is useful, as the serial monitor can be used to visualize the processes that the system is running. The headphone jack can also be used to plug in speakers so that the music can be played out loud.”
The platform, powered by either the ATmega168V (the low-power version of the ATmega168) or the ATmega328V, can be sewn to fabric and similarly mounted power supplies, sensors and actuators with conductive thread.
“I wanted a place where I could experiment with the different sensors, but also something that I could use to show examples of what can be done without constantly uploading code,” he explained.
Key project components?
1 x ProtoSnap – LilyPad Development Board (kit) which includes the following:
1 x LilyPad Simple Board
1 x LilyPad Button
1 x LilyPad Slide Switch
5 x LilyPad White LED
1 x LilyPad RGB tri-color LED
1 x LilyPad Light Sensor
1 x LilyPad Temp Sensor
1 x LilyPad Buzzer
1 x LilyPad Vibe board
1 x LilyPad FTDI Basic
2 x Conductive Thread Bobbin
1 x Needle Set
Duniken also used:
7 x sewable snaps
1 x Piece of fabric big enough to hold all of the sensors
1 x Fabric Marking pen
“Although I had the LilyPad Development Board, I decided to use the LilyPad Simple Board so I could use the extra pins as switches,” he clarified.
After drawing up a diagram using LucidChart, Duniken arranged the sensors and switches on the fabric, using the marking pen to indicate where each pin and component would be placed.
“I removed the sensors and used the marking pen to draw the circuit onto the fabric with a ruler to make sure all of my lines were straight. When I had the lines drawn, I again placed the sensors on the mat to make sure that everything lined up the way I wanted it to,” said Duniken.
“I ended up changing the position of the RGB light slightly so the lines were less likely to make contact with the other pins on the LilyPad. I wanted the lines to be part of the final piece so, once I was satisfied with the diagram, I traced the lines with a permanent marker. If I did it over, I would probably color code the lines so that it can be better used to explain how the circuit works.”
Next, Duniken cleaned off the marking pen, stitched on the sensors and other components, sewed the circuits and sketched the code.
“To ensure that the sensors stayed put while I sewed the circuits, I did a quick stitch with plain thread to hold the components in place. Using the conductive thread, I sewed along each of the circuit lines connecting the different components to the LilyPad,” he added.
“Be careful where the Positive lines (red) cross the Ground lines (black). I used a small piece of plastic cut from the LilyPad packaging to make sure that the lines didn’t short. I used hot glue to tack down the plastic so it wouldn’t snag on anything.”
Interested in learning more about designing your own Arduino Lilypad Sensor Demo Mat? You can check out the project’s Instructables page here.
Jan Henrik has designed a multi-functional police light for model cars using Atmel’s ATtiny tinyAVR (25/45/85) microcontroller (MCU).
The project – which recently surfaced on Instructables – features several “animations” or sequences that can be easily changed by simply pressing a button on the circuit board.
“It has two channels, which can be controlled with PWM,” Henrik explained.
“This allows us to add serval animations or police light flashing sequences. The maximum rated current per channel is 500mA, [enabling] us to control high power LEDs, LED stripes or old light bulbs.”
Aside from Atmel’s ATtiny MCU, key project components include:
Two buttons (off/on)
Two resistors (1kOHM)
Two resistors (220kOHM)
Two resistors (450OHM)
Two diodes (1N4007 or Equal)
Terminals with screws
One 8 pin IC holder
Two BC548 (or Equal)
Un-isolated wire
One circuit board
As you can see in the circuit board layout above, the two output channels are on pins 0 and 1 (PWM outputs), while pins 3 and 4 are designated as input pins for the buttons.
To program the ATtiny, Henrik used an Arduino Uno with a shield, although as he points out, a simple breadboard will suffice.
On the software side, Henrik wrote two separate programs for the police light. The first is easier to understand and alter, while the second features German and American police light sequences, along with a more responsive menu.
A holocron, short for holographic chronicle, is defined by Wookiepedia as an organic crystal-lattice device used to store large quantities of data guarded by the device’s gatekeeper. In the Star Wars Universe, holocrons typically stored information on Force techniques, beginning with the Sith and the Jedi approximately three thousand years later.
1/8th Acrylic sheet in pale blue and dark blue transparent
Primer
Rustoleum Hammered-Finish metallic
Thumb drive
USB cable
Super-bright LED
NoMuse kicks off the project by building a shell consisting of 6 pieces of laser-cut acrylic which, in the original kit, are identical in size.
“If you are making your own, you make them in three different sizes — which makes assembly much simpler. I chose to create the ‘overlap’ on this build by gluing little strips of 1/8″ acrylic rod to selected edges,” he explained.
“Since lasers don’t cut at pure right angles (the cut opens up towards the bottom), [this] meant I had to sand the pieces flat again after gluing. And then sand the whole assembly for quite some time after the box was built. Following gluing, and flat-sanding to as clean as possible, prime it, then address remaining seams and divots with Bondo Spot Putty. Sand again, prime again.”
Next, NoMuse painted the shell, fitted it with translucent plastic, laminated the diffused panels with cut-out patterns and engraved his creation. He then chopped up a USB cable, pried the housing off a thumb drive (the wires from the cut-off end of the USB cable were soldered directly to the exposed pins of the thumb drive), fitted the LED lights, inserted a LiPo battery, swapped in a tilt switch and installed Atmel’s ATtiny85 MCU in a specially designed 8-pin DIP socket.
“The AVR chips can do capacitance sensing natively. Atmel even has a free library. But you can also do it through the Arduino IDE, using the capsense library from the Arduino Playground,” said NoMuse.
“The way the library works, the ‘send’ pin is used to trickle a charge to the receive pin through a large resistor. The time it takes that pin to reach threshold is dependent on the RC value; hence, adding the capacitance of a human body changes it. With a resistor of 1 meg, actual touch is required. With ten meg ohms, you can trigger from a few inches away, and with more than that, you can push it out to a foot or more… This also increases the sense time, [so] to keep the rest of the circuit running smoothly I found it was better to stay with a mid-range value.”
It should be noted that the above-mentioned project builds on earlier work by Instructables members silverjimmy and Groover, who previously posted instructions for laser cutters on the site.
“My idea is to take an old printer and turn it into a vinyl cutter, as they are quite similar in there design and it would hopefully make the build just that little bit easier,” LiquidHandWash explained.
“As most people find the electronics an software the most intimidating part of a project like this, I’ve gone into a fair amount of detail on how to set it up. Turns out the mechanical part of this project is far more challenging, as it takes quite a bit of tweaking, adjusting and general head banging to get the vinyl to cut properly.”
Aside from an old printer with stepper motors, key project components include:
2X EasyDriver Shield stepping Stepper Motor Driver
Relay module shield board for Arduino Automotive relay
The first step? Determining where the the Arduino, relay and easy drivers will fit by removing all the old electronics and making a laser cut board to mount the components.
“Once that was done it was time to start using some of those Dupoint wires, they make every thing very easy to wire up,” said LiquidHandWash.
“Just pull a pin out of the headers and plug it in if you want to make the end of the wire male.”
Next up? Identifying the four wires on the stepper motor, wiring up the Arduino, installing and configuring the relevant software/sketches, modifying Inkscape, installing the blade and electromagnet, fitting the cutter and applying the sticker.
Serial monitors are typically used to help Makers and engineers more easily debug their projects.
However, as HackADay’s Will Sweatman notes, traditional serial monitors require a PC or laptop loaded with a terminal program.
“Most of the time this is not an issue, because the PC is used to compile the code and program the project at hand,” Sweatman explained.
“But what if you’re in the field, with a mission of fixing a headless system and in need a serial monitor? Why lug around your PC when you can make your own external serial monitor?”
Although the minimalistic platform lacks a keyboard port like some other external monitors, tact switches facilitate access to the user interface (UI) for start and stop commands. As expected, the tact switches can also be used to set the baud rate.
