A Surprisingly Simple Omnidirectional Display

November 22, 2024 by Danie Conradie 34 Comments

Old-school technology can spark surprising innovations. By combining the vintage zoetrope concept with digital displays, [Mike Ando] created the Andotrope, a surprisingly simple omnidirectional display.

Unlike other 3D displays, the Andotrope lets you view a normal 2D video or images that appear identical irrespective of your viewing angle. The prototype demonstrated in the video below consists of a single smart phone and a black cylinder spinning at 1,800 RPM. A narrow slit in front of each display creates a “scanning” view that our brain interprets as a complete image, thanks to persistence of vision. [Mike] has also created larger version with a higher frame rate, by mounting two tablets back-to-back.

Surprisingly, the Andotrope appears to be an original implementation, and neither [Mike] nor we can find any similar devices with a digital display. We did cover one that used a paper printout in a a similar fashion. [Mike] is currently patenting his design, seeing the potential for smaller displays that need multi-angle visibility. The high rotational speed creates significant centrifugal force, which might limit the size of installations. Critically, display selection matters — any screen flicker becomes glaringly obvious at speed.

This device might be the first of its kind, but we’ve seen plenty of zoetropes over the years, including ones with digital displays or ingenious time-stretching tricks. Continue reading “A Surprisingly Simple Omnidirectional Display” →

Tidy POV Display Using The ESP32

November 23, 2022 by Dave Rowntree 9 Comments

Chinese Youtuber [corebb] presents the second version of his POV display. The earlier version used 5050-sized SMT addressable LEDs, which didn’t give great resolution, so he rev’d the design to use a much higher number (160 to be exact) of APA102 LEDs. These are 2mm on the side, making them a little more difficult to handle, so after some initial solder paste wobbles, he decided to use a contract assembly house to do the tricky bit for him. This failed as they didn’t ‘understand’ the part and placed them the wrong way around! Not to be deterred, he had another go with a modified solder stencil, and eventually got the full strip to light up correctly.

Based on an ESP32 (using the Arduino stack) and SDCard for control, and a LiPo cell charged wirelessly, the build is rather tidy. A couple of hall effect switches are mounted at the start of each of the two arms, presumably lining

up with a magnet on the case somewhere, although this isn’t clear. The schematic and PCB appear to have been designed with JLCEDA, which is a repackaging of EasyEDA. We can see the attraction with the heavy integration of this with the JLC and LCSC services. It appears that he even managed to get streamed video working — showing a live video from a webcam — which is quite an undertaking to pull off when you think how much processing needs to happen in real-time. As he alludes to in the video, trying to increase the resolution beyond this point is not viable with the processing capability of the ESP32.

A resin-printed case finishes off the build, with a screw-thread mount added to the rear, to allow typical camera mounts to be used to hold the thing down. A smart move we think.

We love POV displays around here, this spherical POV display is especially fabulous, but you don’t need fancy hardware if you have a handy ceiling fan and a bit of protoboard spare.

Continue reading “Tidy POV Display Using The ESP32” →

The Basics Of Persistence Of Vision Projects

October 29, 2019 by Lewin Day 6 Comments

Persistence of Vision (POV) is a curious part of the human visual system. It’s the effect by which the perception of an image lingers after light has stopped entering the eye. It’s why a spinning propeller appears as a disc, and why a burning sparkler appears to leave a trail in the air. It’s also commonly used as a display technology, where a series of flashing LEDs can be used to create messages that appear to float in the air. POV displays are a popular microcontroller project, and today, we’ll explore the basic techniques and skills required in such builds.

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POV Tops Hobbyist Abilities

December 29, 2018 by Brian McEvoy 11 Comments

Sometimes a beautiful project is worth writing on that merit alone, but when it functions as designed,someone takes the time to create a thorough and beautiful landing page for their project, we get weak in the knees. We feel the need to grab the internet and point our finger for everyone to see. This is one of those projects that checks all our boxes. [Nathan Petersen] made a POV toy top called Razzler, jumping through every prototyping hoop along the way. The documentation he kept is what captured our hearts.

The project is a spinning top with an integrated persistence-of-vision (POV) display. That’s the line of LEDs that you see here. To sync up the patterns, the board includes an IMU, but detecting angular velocity with either gyroscope or accelerometer proved problematic. [Nathan’s] writeup of this is worth the read itself, but you’ll also enjoy the CNC workworking part of the project used to create the body of the spinning top.

This was [Nathan]’s first big solo project, and so many of the steps are explained by someone who just entered the deep-end very quickly. If you have experience, you may grin at the simplified reasonings, but for a novice, it makes for an approachable lesson. The way he selects hardware and firmware is pragmatic and perhaps even overkill, so you know he’s going into engineering. This overshot saved him when there were communication problems which needed a sacrifice of some processing power to run I2C on some GPIO.

We hope you enjoy reading about this combinations of POV, firmware (or is it?), and centrifugal force.

FPGA Persistently Rick Rolls You

June 11, 2018 by Al Williams 13 Comments

When [Im-pro] wants a display, he wants it to spin. So he built a persistence of vision (POV) display capable of showing a 12-bit color image of 131 x 131 pixels at 16 frames per second. You can see a video about the project below, but don’t worry, you can view it on your normal monitor.

The project starts with a Java-based screen capture on a PC. Data goes to the display wirelessly to an ESP8266. However, the actual display drive is done by an FPGA that drives the motor, reads a hall effect index sensor, and lights the LEDs.

Continue reading “FPGA Persistently Rick Rolls You” →

Building A POV Display On A PC Fan

April 21, 2018 by Richard Baguley 18 Comments

We’ve covered plenty of persistence of vision (POV) displays before, but this one from [Vadim] is rather fun: it’s built on top of a PC fan. He’s participating in a robot building competition soon and wanted to have a POV display. So, why not kill two birds with one stone and build the display onto a fan that could also be used for ventilation?

The display is a stand-alone module that includes a battery, Neopixels, Arduino and an NRF240L01 radio that receives the images to be displayed. That might seem like overkill, but putting the whole thing on a platform that rotates does get around the common issue of powering and sending signals to a rotating display: there is no need for slip connections.

[Vadim] goes into a good level of detail on how he built the display, including the problems he had diagnosing a faulty LED chip, and why it is important to test at each stage as it is easier to debug when the display isn’t whizzing around at high speed.

It’s a bit of a rough build that uses more protoboard than might be necessary, but we’re keeping our fingers crossed that it doesn’t fly off during the competition.

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Celebrating The Olympics With Flaming Windmills

February 9, 2018 by Tom Nardi 5 Comments

Like many of us, [Gustav Evertsson] was looking for an excuse to set stuff on fire and spin it around really fast to see what would happen. Luckily for him (and us) the Winter Olympics have started, which ended up being the perfect guise for this particular experiment. With some motors from eBay and some flaming steel wool, he created a particularly terrifying version of the Olympic’s iconic linked rings logo. Even if you won’t be tuning in for the ~~commercials~~ Winter Games, you should at least set aside 6 minutes to watch this build video.

The beginning of the build starts with some mounting brackets getting designed in Fusion 360, and you would be forgiven if you thought some 3D printed parts were coming up next. But [Gustav] actually loads the design up on a Carbide 3D CNC and cuts them out of wood.

A metal hub is attached to each bracket, and then the two pieces are screwed onto a length of thin wood. This assembly is then mounted up to the spindle of a geared motor rated for 300 RPM. The end result looks like a large flat airplane propeller. Five of these “propellers” are created, one for each ring of the Olympic’s logo.

Once the sun sets, [Gustav] takes his collection of spinners outside and lines them up like windmills. At the end of each arm is a small ball of fine-grade steel wool, which will emit sparks for a few seconds when lighted. All you’ve got to do is get the 10 pieces of steel wool alight at the same time, spin up the motors, and let persistence of vision do the rest. If you can manage the timing, you’ll be treated with a spinning and sparking version of the Olympic rings that wouldn’t look out of place in a new Mad Max movie.

Generally speaking, we don’t see much overlap between the hacker community and the Olympics. You’d have to go all the way back to 2012 to find another project celebrating this particular display of athleticism. We would strongly caution you not to combine both of these Olympic hacks at the same time, incidentally.

Continue reading “Celebrating The Olympics With Flaming Windmills” →