Picture of Hard Drive Persistence of Vision (HDPOV)
Test Pattern 1 - Upclose.JPG
Test Pattern 2 - Upclose.JPG
System - Perspective.JPG
System - Above with Platter.JPG
System - Above without Platter.JPG
The platter of a hard drive spins well over sixty times a second. If a narrow slot was cut into the platter to allow LEDs to shine through, we can achieve flicker fusion and trick the eye into seeing a stable image. This phenomenon is known as persistence of vision (POV). There are many examples of LEDs being used for POV, building an image by moving the LEDs or having the observer move relative to them. The LEDs used in this project do not move, and the image is built using the interference of the slotted, spinning platter.

The system works by timing the slot in the platter. The Arduino uses an internal timer to clock each revolution. It achieves this using an infrared gate, which triggers a hardware interrupt on every full revolution of the platter. The Arduino uses the revolution time and phase to schedule a second internal timer. This second timer uses an interrupt to schedule the timing of the LEDs, firing tens of thousands times a second to build a stable, visible image.

This work is based on Ian Smith's version of the same. His work is excellent, and his website on this topic will help provide a complete picture for this instructable.

mad4hatter1 year ago
How do you power the motor on the hard drive to get it to spin? I don't see it in the circuit and I'm not sure which wires to use on the sata power cable.
XxRyan787xX2 years ago
Hi, I have finished building your version of the led hard drive clock, your work is remarkable.

One thing that i can not get working is if i press "r" to display the rpm and such, it will give me a reading of about 8000RPM, although if the key is pressed at the right time the rpm reads as something around 30000RPM - 45000RPM. I have tryed playing around with the sensor, the 'SPURIOUS_INT' Value and the gap in the platter, none however have given me a result. This ubove is causing lodes of visible glitches and the pattern is all messed up (Test Pattern 1).

Any help from Vishnubob or the community would be greatly appreciated.

Note: I have bypassed the start-up pattern because it does the red animation but stays red and does not cycle through the colors.
The python script is giving me a hard time, I am using windows 7 and have python 3.3.
I get this error, invalid syntax: no module named serial, this happens with time also.

Where can I download serial and time?
Do I have to tell the script where to look for these?

Any help would be greatly appreciated.
h4x0rZ2 years ago
Everytime I try to open the clock.py Script in Python it tells me that there's an Syntax error?

File "clock.py", line 41
print "send => %s % msg.strip()"
                                                           | this last symbol is wrong?!
SyntaxError: invalid syntax
muztard2 years ago
Here http://steyer-tec.steyer-art.de/?page_id=32
s my version of an HDD POV Clock with the help of the Articles from Vishnubob and David Hend ( http://www.instructables.com/id/Hard-Drive-POV-Clock/ )

THX to Vishnubob and David Hend! Great Work!
sonkaraman3 years ago
please can anyone tell me about the HD port like wat exactly it is and where do we
connect the HD port.
JXplicits3 years ago
This sketch is just the test pattern and not display the hours like the video, Right?

Sorry for my english if there is any mistake.
Umm, i think its for both, there is a file called clock.py that has to be open by some sort of program.

Go to step 14. Good luck!
Cobra_Phil3 years ago
There is a project at kickstarter about a POV hard drive clock...
jberwick13 years ago
anybody else having a hard time with python/serial/mac?

its giving me a bunch of trouble, and id hate to give up on such an awesome project, right at the end.
velaron5 years ago
Hello all I am wondering, can i use hall sensor ?
teknobudd6 years ago
The ANODE is the longer and the cathode is the shorter leg of just about any L.E.D. A phototransistor's shorter leg is the collector and the longer leg is the emitter. You can look at any LED from either top or bottom and you will notice its base has a flat side - that is the cathode side. In the case of a phototransistor, the flat side indicates the collector side. Your instructions should work, but the terminology is incorrect.
Bozza6 years ago
Hey, just wondering what brand and how old the hdd u used was. ive opened up two seagates, which at first seemed to spin without stopping, however once the reading arm is removed, they only spin for bout 30secs and then stop. Is there any way to mod the drive to prevent this?
DJNASHA Bozza6 years ago
remove the read arm!
Derin Bozza6 years ago
Try to gut the arm and keep the inner parts(coil,for example) plugged in.
zh111076 years ago
capslock makes you sound rude
vishnubob (author)  get to da parakeet6 years ago
I use ATX power supplies harvested from old machines.
Jimwright6 years ago
My friend Richard M and I finished one today, and it's great! I don't know if my one small problem was the result of using a LED / sensor gate from a floppy drive (see comment below), but it wouldn't sync until I widened the disk gap a little (less than 1/8" total). So, be forewarned.
vishnubob (author)  Jimwright6 years ago
Congratulations! That's awesome! If you can, please post pictures of your rig, I would love to see it. The sensor required the most tuning, I'm not surprised you had to make this adjustment. Did the code work well for you?
Well, mine looks mostly like yours. The wood blocker is one piece, due to the small size of the IR gate. (Pix #2 is the gate, before I removed it from the PCB of the junked floppy drive.) I cut the RGB tape very short and scraped the traces bare to solder on a compact 4-lead ribbon cable. The RGB tape stuck OK. I alcohol-wiped the surfaces and washed my hands. Oh, and 2 coats of varnish on the wood. Otherwise, I'm sure the tape wouldn't stick. I chopped a segment out of the spacer ring below the disk to counter-balance, but it's too much. (You can see the removed segment in the pix.) I wound up adding a lot of screws/washers to the hub to un-compensate. It runs smooth. I didn't get a pix of the completed unit with the IR detector installed. It clamps right in the shallow wood slot. The software runs just like your video. Mine has a very slight jitter. No big bother. I want to make an arduino-less version. I think it is feasible to trigger the RGBs with 3 disk-edge slots and adjustable delay RGB triggers. My electronics basics is Nike Hercules school, but I'm much encouraged by your pioneering. THANKS.
Almost Done.jpgDetector from FDD.JPG
Jimwright6 years ago
I ripped open a 3 1/2" floppy drive and found a LED / sensor. (Lots of them in printers too, as I recall.) It even had a diagram on the back of the pcb that matched the schematic here. I rigged it up with the 270 and 10K resistors, and it put out a great 4.7V when the gate is blocked. What's nice about it is that it's very compact (and free).
frollard6 years ago
Instead of using the slot as a thru-device could you mount the ir led AND photo-ransistor up-facing under the platter, with the platter painted ir-reflective 'white', then the slot would pass overhead, causing a flicker on the transistor... You might need to use an analogue line to read it, as it wouldn't be nearly as defined, especially for the slot size. If the slot could not be detected, simply paint an infrared-black dot on the underside :D AWESOME PROJECT! I'm just waiting for a drive to die now :D
I saw this on YouTube and I've been waiting for you to make an instructable of this! I'm stoked! Thanks for this instructable!
shmolky6 years ago
I'm in the process of building one of these myself... very cool. One thing I'd add that I had to learn is that older, smaller drives often use glass based platters that have the magnetic coating/film on top which can be sanded away. What's cool is you don't lose much in the way of balance, but on the negative side it's a little harder to sand away the magnetic coating on both sides (to make a clear slit) and I don't think you let quite as much light through as compared to: Newer, more higher capacity drives use aluminum based platters which you can cut through easily, but also would unbalance the spinning platter.
GBMorris6 years ago
This is really cool. What would you say is the total time and cost of this project?
vishnubob (author)  GBMorris6 years ago
Thanks for your comment. If you have a few drives on hand, you will spend less than $50 in parts. It took me twelve hours to fabricate, but that was an ad-hoc process. With parts and instructions, you could build this in four hours.
That's hella slick. I'm not so sure about cutting the slot all the way through the platter though(and I'm definitely not the most safety conscious one around). If it was to come apart, that thing could have an eye out, or, worse yet, bust up such a sweet project...
Guy.Fawkes6 years ago
Hard drives normally come in 4 speeds: 5400 RPM, 7200 RPM, 10,000 RPM, and 15,000 RPM. The latter two speeds are "expensive" and "insanely expensive," so you will most likely be using 5400 or 7200 RPM drives that equates to 90 or 120 revs/second (exactly 1.5 or 2 times the AC flicker rate in North America, 1.8 or 2.4 times the European flicker rate).
fwjs286 years ago
qwertyboy6 years ago
this is so cool! i'd make one if i had any old hard drives and an arduino, but i don't have either.
It creates some interesting effects in the video, if you play around with multiples of frame rates you'd get some interesting stuff, also if you can find a rough speed that's just about below POV effects then you could do the same effects in front of people, but it may case motion sickness...
now add a dvd capabilities and it would be the GREATEST gadget in the universe!
S1L3N7 SWAT6 years ago
This may have been helpful. http://www.sparkfun.com/commerce/product_info.php?products_id=247

It's a prebuilt version of the IR trip gate.

Very Cool though! 5 stars!
JakeTobak6 years ago
Wow, that's trippy. I want one.
jeff-o6 years ago
Nifty! Did you use 4800rpm or 7200rpm hard drives? Does it matter?
karossii jeff-o6 years ago
he said well over 60 times per second; there are 60 seconds in a minute (the 'm' in RPM); so 60x60=3600... I would assume that even 4800 RPM would be considered well over 3600... so it should work fine if you time it out as described.
jeff-o karossii6 years ago
It's more an issue of whether the microcontroller can keep up, but considering that the Atmel can do, at least 1 million ops per second, I guess it doesn't matter and my question was pointless. ;)
vishnubob (author)  jeff-o6 years ago
I used a 7200 RPM drive. As long as the drive spins well over 30 times a second, it should work fine.