MRI stands for Magnetic Resonance Imaging. So, the SpokePOV uses a Magnet to measure wheel rotation, and derives the Resonant frame rate by timing Magnet readings, and then it makes the Image appear, as if by some kind of circular magic, on the bicycle wheel! Thank you Adafruit, for this super cool toy! I use it to make legit brain-scan on a bike! I made two images of brains and fine-tuned in the SpokePOV software.
We used a serial-to-USB converter to be able to upload images to the computers, each of which has enough space for four different images, allowing us to create animations or just to display a rotating set of images.
For my first go, I tried a portrait of Carl Sagan. Because we only have one color, I had to find a simple portrait that was easy to reduce to a single color. I found this one on Google Images, and turned it into this.
SpokePOV Kit – v1.1 – One single SpokePOV fits in one wheel, you can add as many SpokePOVs to a wheel as you’d like get a better image. With one spoke, persistence at a speedy 15mph. Two spokes for cruising at 10mph. Three for a leisurely 7mph! Read more about specifications, full instructions, usage, etc. at the SpokePOV webpage. (read more)
This project was made by 3 students of Télécom ParisTech as part of the Embedded Systems course (ELECINF344/ELECINF381 aka ROSE). At the beginning in February 2012 our initial goal was to create a display device using persistence of vision. The main interest of this type of device is that we obtain images carved in our retina but the device is moving so quickly that we cannot see it. Thus our images seem to float in the air.
Many POV devices already exist but they are often limited to simple display patterns, such as clocks or moving text. Some of them can display pictures or videos but these media often have to be preregistered in a memory on the device. We wanted to create a universal device able to display whatever you want whenever you want.
I’m working on several projects almost perpetually. Getting the time to complete one project before being distracted by another is the real trick. My most current project which is almost done is running my bicycle tire in a test rig using a scavenged AC motor. The test rig is so my daughter can work on her SpokePOV kit from Adafruit at the lab bench and the motor will make it easy to spin up the wheel to check the image and/or animation. It takes longer for these projects because I document it all and shoot video for my ToddFun blog. This build includes welding, repairing the scavenged motor and building a 120v AC to 15v DC power source to run a cooling fan to cool the AC motor. The cool part is I built the 15v DC source using only a light bulb, diode and capacitor and showed the viewers how to correctly calculate the required wattage light bulb and what is important to get it right without getting into too much engineering.
Each SpokePOV is drawing its power from a LiPo Battery.
These are 1/3 the weight of the standard AAs (based on using three of them).
Also, they are rechargable, and keep their juice for ages.
They plug into the board via a little connector soldered to the board at J1.
These are attached to the board with velcro pads and a cable tie through the holes for the AA battery clips.
I wanted to go with just velcro, so I could pop the batteries off for recharging, but it didn’t feel secure enough.
I applied several coats of Silicone Conformal coating to seal the board, and checked it with a UV lamp.
Hopefully this should be OK to protect my SpokePOVs from Vancouver’s not-so-dry climate.
I also covered the LiPo Batteries in heat-shrink tubing and closed-off the ends with silicone sealant (the stuff you’d use for a bathroom).
Where the LiPos plug into the board, I made a little jacket out of heat-shrink that slides over the connector (I can post more pictures if anyone is interested).
Finally, I bought connectors to cover the I/O ports and plugged any gaps in them with the sealant.
After all that work, I didn’t want my SpokePOVs nicked, so I tried my best to make it difficult for them to be removed.
At the top connector, where the spoke is a little fatter, I bolted the SpokePOV to the wheel with a nylon cable clamp.
Then, at two of the other connections I used metal wire and threaded it around the spoke using a technique similar to one I found via the Monkelectric website.
Now thieves will at least need a screwdriver, scissors, pliers and a lot more time to relieve me of my goods.
Let’s hope they don’t just decide to cut my spokes…
What did I spy at my hackerspace, Pumping Station: One, in Chicago at our weekly meeting last night? Nothing other than a blue SpokePOV kit mounted in a box fan lookin’ all awesome!
Our most excellent member, Crimson, decided to take the SpokePOV from one wheel of the our TRON lifecycle (made for the Scion Hackerspace Challenge). He removed the fan blades since it was 5 bladed instead of 3 blades. Then he cut out of plywood a new 3 legged propeller and attached the 3 SpokePOV boards with zip ties. The magnet is affixed to the fan grill and the hall effect sensors detect it well.
I feel much better about the viability of my project now that I’ve seen Crimson’s work! Just in time as I’ve got 12 blue SpokePOV boards arriving tomorrow
When my “hokey spokes” bike lights started to go out (due to age) and I couldnt get “Bike Party” to show up in the programable lettering I started looking into a new wheel mounted bicycle light. I found some unbeleivable wheel lights called “Spoke POV“. It took me many times looking at their website and pictures of the lights to figure out how they work.
Its a “kit” you have to assemble yourself with all the circuits, pcb board and led’s. You buy it in pieces and solder every one into the board. Then the lights can be programmed from your computer thru a USB cable and dongle. There are 4 “banks” that will hold the graphics or lettering or anything you want. You set the “revolution count” to whenever you want it to change to the graphic in the next bank.
I wanted to share my experience using the SpokePOVs in what would be considerd “harsh” conditions. They not only survived 12 days, 2 rain storms and masses of playa dust, but worked like champs- all 6 on my BurningMan bike. Photos that it actually happened are attached
This is a testing rig I constructed for my SpokePOV kit. I used an old bicycle, ceiling fan motor and wiring from an old lamp. It works great as a bench test rig when programming and testing my SpokePOV boards on the wheel. It could also work as a cheap display device.