Although [Serokoy] is not thrilled with the outcome of his Nipkow disk clock (translated), but we really enjoy it. It uses the Persistence of Vision concept to create a light display from a rotating disk.
We’ve come across a lot of rotating disk clocks. Several were based off of the platters of a hard drive, using a slit, or series of slits to make up the display. This Nipkow disk uses a similar technique but in a more general way. The series of holes arranged in a spiral pattern allows a grid of concentric rings to be used as pixels when the disk is spinning. The bottom portion of the disk is used as the display area. Each pixel is illuminated at just the right time by LEDs below in order to freeze that pixel in the viewer’s eye. The demo is a bit rough, and [Serokoy] mentions that the precision of the hole layout makes all the difference. He drilled these by hand in a CD which was spray painted matte black. Even though he used a computer to lay out and print a template, it took four tries to get a suitable disk.
The more we think about this one the more we like it. [Michael] built himself a wind-powered persistence-of-vision weather station. Okay, that sounds interesting, but he ups the ante when you find out what’s included in the system.
A stepper motor acts as the generator which powers the electronics. As we’ve seen before; if you spin the shaft of a stepper motor electricity is produced. [Michael] is actually spinning the housing of the motor, with the shaft mounted to the base that holds the weather station in place. This way, the electrical contacts are spinning along with the blades of the generator. By mounting all of the electronics on these blades he gets around the problem of transferring power onto a spinning platform.
A set of LEDs on the end of the blades display temperature and relative humidity readings. A hall effect sensor pulled form an old floppy drive syncs the display with the rotational speed. He’s even got a shunt system which keeps the input voltage at a safe level, and will act as a break in high winds to keep the rotors from spinning out of control. See what we mean? An interesting idea because a fantastic project when you build in features like these!
Flashing LEDs for a persistence of vision display are on bicycle wheels, alarm clocks, and even light painting sticks to draw images in the air. What if you wanted to plot an image in the air (translation) with a single LED? That’s what [acorv] did after taking a cue from a polar plotter.
Like the polar plotter and Drawbot, [acorv]’s build began with a pair of stepper motors and fishing line (translation). [acorv]’s brother upped the stakes a bit and suggested replacing the marker with an LED and taking long exposure photographs. Armed with a DSLR and a lot of patience, a few experimental pics were taken. To plot the image, the Lightbot flashes its LED as it goes across the plot area. The process of building an image pixel by pixel takes a while – eight minutes for this image – but the brothers were encouraged enough to take their rig outside.
After setting up the polar plotter between two tripods, [acorv] and his brother made this image in the dead of night. It’s an interesting spin on the POV LED builds we’ve seen before. Check out [acorv]’s Lightbot slowly drawing something after the break.
Continue reading “Plotting pictures with light”
This hard-drive based POV clock is a treasure trove of great design choices. Now, we’ve seen a bunch of spinning clock builds. Several of the hard drive versions use slits cut in the platters to create a display by illuminating an LED behind those slits at just the right moment. This is a similar idea but [Jason Hotchkiss] ditched the platters all together and replaced them with a light filter. The filter disc has digits 0-9 as well as a colon (not seen above because the colons blink each second). As this disc spins, the Arduino compatible controller lights up LEDs in the eight digital positions to illuminate the correct number.
The filter is made from an etched copper-clad disc. This is a great choice because the fiberglass substrate is strong, light weight, translucent, and available. The filter idea also means you don’t need to get power or data to a spinning platform. [Jason] has also designed a very impressive controller board that is the same size as the footprint of the laptop hard drive he’s using. Check out the video after the break to see his description of what went into the hardware choices he arrived upon. Continue reading “POV clock spins light filter instead of LEDs”
Confronted with the issue of finding a use for his mounting pile of junk electronics, [Rue] set out to build a persistence of vision device using a hardware state machine. We have a suspicion that his original link may go down if there’s too much traffic so here’s a cached link just in case.
Any board that is MSC-51 or MCS-48 based would have worked for his purposes. This is because the addressing scheme of the hardware makes it an easy hack. The image above shows him cutting off the processor from this board. It was chosen because of a 74HC373; it was a mistake at first but since it’s pin compatible with the 74HC374 that he needed a simple swap did the trick. From there a clock source was added, and the address information necessary to display the message was burned into an EEPROM.
Step twelve of his writeup shows a Morse Code message created by attaching the board to a broomstick and twirling it around in an arc. We took just a minute to decode the message and believe it’s a shout-out to Hackaday. Nice, thanks for reading [Rue]!
[Ryan]’s cylinder POV display is an amazing piece of work. Right now it’s impressive sitting on his workbench, but we’re sure it would be astonishing hanging above the middle of a dance floor. There are 64 RGB LEDs on this display and they’re certainly bright enough to liven up any space.
Power is provided through a slip ring. The ground is connected to the shaft of the motor [Ryan] picked up at an auto parts store. It’s an efficient way to do things, but the display can only be controlled by whatever image is stored in the ATMega1284’s flash memory. [Ryan] admits this isn’t an ideal setup so he’s working on a ZigBee or Bluetooth connection.
We’ve seen some amazing spinny POV cylinders, but [Ryan]’s build looks amazingly professional. All the board files, schematics and code are uploaded, as well as an image converter for BMPs and PNGs. Check out the demo after the break.
Continue reading “Tubular POV display”
[Ch00f] spent some serious time figuring out how the Icebreaker POV toy works. This is a pretty cool device about the size of a toothbrush holder. It’s in a clear plastic case, which lets the row of 32 surface mount LEDs shine through. But making light isn’t their only function. You can use the device to scan in a high-contrast design, then ‘play it back’ using the persistence of vision display properties of the LED strip.
Perhaps the biggest question on [Ch00f’s] mind was how the sensing is done. He made a series of observations, then started monkeying around with the LEDs to investigate them. It seems that one LED is lit up while the ones around it are used as light sensors. This becomes more confusing once he realized that the display was multiplexed.
His write-up includes a collection of schematics that can be pieced together to conceptualize the entire circuit. The image above was taken during this process, using an LED to check the connections on a part. This let him prove that it’s an N-channel MOSFET. He plans to take what learned and roll it into his own project.