Building a POV, Propeller Clock motor

Meanwhile the Propeller Clock of Bob Blick is known quiet well in the DIY communities http://www.bobblick.com/techref/projects/propclock/propclock.html .
Some people do crazy things http://www.ledcontrol.narod.ru/eng/index.htm .

One problem building such a clock is to find a motor. The motor has to be silent, it has to make more than 25 turns per second and the power for the clock circuit has to be transfered somehow to the pov pcb that is mounted on the turning spindle of the motor.

Bob used a motor from an old floppy disk drive in his project. He modified the motor to use an extra coil as a generator for powering of the circuit. The motor that bob used was a non regulated one from a very old floppy disc drive. These are hard to find nowadays and the speed is not very stable.
Daryl bender http://www3.sympatico.ca/surfin.dude/creative/clocks/propclk/blick.html also modified a motor. Other people transferred the power using brushes. Brushes make noise, give bad contact and are ugly ...
One can also mount a battery onto the moving part http://www.atomicfireballs.com/pivot/entry.php?id=53#body , but this battery need to be replaced now and then.
Phillip used a fan as a motor and build his own generator http://www.activevb.de/rubriken/kolumne/kol_27/propclock.html .
Here are many links to different solutions http://www.luberth.com/analog.htm and pictures of clocks that use brushes to transfer the power to the pcb.

I decided to solve most of the problems by using motors of old 5 1/4 inches floppy disc drives. These motors are brushless dc motors that are very silent while running. They are cheap. The build rather big mounting platforms. The speed of the motors is rather constant because it is regulated. The motors should be found rather easy in surplus stores for a small amount of money.

Step 1 What you need

Material
- two motors with working circuit boards
- one voltage regulator 7805
- one variable resistor (values depend on the circuit board. mine was 50k Ohms)
- one capacitor (value depends on the circuit board, mine was 10nF)
- glue, best use is epoxy based
- some material to fill "space! (I used broken experimental pcb boards)

Tools
- a soldering iron
- pliers
- solder
- screwdriver
- dremel tool
- ... the standard stuff ... ;-)

Comments

[dumfart]

Hmm, anybody tried this using cdrom drive motors?

[swimray5]

Hey, I know this may be a stupid question, but what are you grounding to here?

[frickelkram]

Ahhhhh, philosophic question ;-)
There is no ground in free air ... is it?

I use the sign that you see on the picture as a common signal. If I would have drawn a real ground, in terms of an "earth" connection, I would have used this symbol;
http://de.wikipedia.org/w/index.php?title=Datei:Symbol_Ground_%28common,_horizontal%29.svg&filetimestamp=20060626175918

Does a Wikipedia page for this, exist for the US also?
http://de.wikipedia.org/wiki/Liste_der_Schaltzeichen_%28Elektrik/Elektronik%29

[swimray5]

Ok, so let me get this straight, in the physical system there is no "ground" ? I'm just wondering what the actual wire connects to. After powering the LED, the negative end goes where?

[ls00181]

it connects just before the capacitor (ie to the common end of the coils)

[The ed]

must the motor have specific rpm or something like that? Can I just buy a motor from any electronic shop?

[Algag]

he said it must make at least 25 turns per second so you would need 
25*60= minimum RPMs or 1500 RPM

[The ed]

ok, thanks. So can I just buy a motor with 1500RPM and make it the motor to turn the clock?

[Algag]

 yes that should be fine

[The ed]

Great, thanks a lot

[Algag]

 anytime

[aqil]

gurandil2..

[emdarcher]

that looks like the inside of the motor I took out of a cd-rom drive that I cant get to work. how do you get those motors to work?

[killerjackalope]

Just had an idea of how to power a generator from the motor, has a mounted cog spinning around a toothed ring, the cog spin the motor, does that make sense?

[frickelkram]

Sorry, but I don't understand what you mean. Could post a small sketch of you idea?

[killerjackalope]

There's an overhead view, hope that helps explain...

[frickelkram]

OK, I see. Basically this setup generates some electrical energy. Having only one small magnet and one coil the setup will generate energy pulses and not a sinus curve of ac current. You can store this energy in a capacitor to store it while there are no pulses. Basically I believe that this setup is not very efficient. It would be ok for the detection of zero crossing but I am pretty sure that you don't get the energy out of it that you need for powering of the pov electronic. You could increase the energy pulses using very, very strong magnets and a coil with many, many windings. Also the airgap between the magnet and the coil should be very, very small. At least you can make the motor turn fast to have a high pulse rate. Also keep in mind that the motor should not turn too fast. If you have high rpm rate of the motor it will get louder, the microprocessor needs to be faster and the led's need to have high light emitting rates, because they will be lit only for a very short time. Things are easier if you let the motor turn rather slow, just over the 50 turns per second rate is ideal. This is the rate where the human eye does not realize a flickering of the display. Most pov displays turn slower than that ...

[gizmohigh69]

OK I have a question aim a lazy person but I love electricity and my license is suspended and I can't drive so aim trying to figure out a way to hook up my bike to a motor and run off the motor but the thing I want to do is charge it using a magnetic coil when I petal the bike that spins the coil and charges it so what I need to figure out is how to make a coil that will spin and charge and make enough power to pull me and the bike and I can add capacitors to it but I don't really have a good idea maybe you can help

[killerjackalope]

just an idea becasue people seem very reluctant to try and generate the power through fields... The main problem with this is noise however four small motors on counterbalancing eachother would just about make the power requirements.

[Derin]

i found 7805 in an ups woot

[mcdonn123]

I've got one just like that, only smaller. And I can't wire it very easily because it connects to one of those flexible copper colored things.

[heavy.metal.nguyen]

I've always wondered what those do. I found two of them in a VCR and I just like the look of them.

[TheMadScientist]

hell yeah, FINALLY a use for those damn old disk motors... they Looked useful, but I just hadn't found a use for em yet...

[codydean]

im 13 and ive been doin stuff like that

[ReKa]

Happy New Year! Looking on an old 3,5 inch disk drive I saw a little magnet and a sensor which are doing revolution detection there. Perhaps its a usable hint for you?

[Heliosphan]

That is ingenious! I myself tried building a POV device using a PIC chip and a long line of LEDs, but I used an onboard battery. As you can expect, the results weren't to my satisfaction. So I hit a brick wall because all the solutions I've seen, as you say, involve xferring power thru contacts in or around the motor. This solution is a great way of doing it, I'd imagine its quite efficient too, you end up losing a bit of efficiency by having to haul the generator round and round but it is truly a wireless power source - Electric fields do it instead! I'm amazed, thanks a lot for this but hacking motors is a bit out of my league really and I'd imagine out of a lot of peoples league. On a side note, how do you implement full revolution detection for the microcontroller? I'd imagine a hall effect sensor? I actually tried using a bike computer sensor myself. It worked well but the sensor housing was too big for my design. A hall effect sensor is surprisingly elusive here in Blighty so I packed the whole project in - too dejected with all the failures. Thanks, a great instructable - difficult to describe thoroughly.

[frickelkram]

Hi Heliosphan, thank's for the flowers ... One of the main points to do exactly this modification was that I think it is too difficult to open a motor and modify that motor like bob did. The design I used here is rather easy. Takinf the motors apart is no problem. The only thing that is a little difficult is the exact mounting of the generator. Just give it a try if you find some of those old 5 1/4 inch drives ... The full revolution detection is still in the design phase. It is not possible to take that signal from the coils that give the power because thsi information is not aboslute. It can only used to measure the revolutions per second. I counted 30 poles on my "generator". Taking one coil that means 10 impulses per full revolution. There more than one solution for the "zero crossing" detection. I experimented with a small photo electric sensor from an old ball mouse. It works well but it does not look nice ... ;-) Next try will be with the hall sensors I kept from the motor that I used as a generator. They are pretty small. On the picture you can see the three small chops with the four pins on the right edge of the picture, mounted in a curve. These hall sensors where used to measure the rotation speed. There are other possible solutions for sensors but I don't like to buy parts for that. I love to reuse old parts as much as possible ... :-)

[burningsuntech]

Nothing like a simple answer to a complex problem. Nice job! I'm building one. Keep up the good work.

[frickelkram]

Thank you for all the nice comments ... I'll keep on going ... I am trying to find a good solution to put the spinnig disct into balance. Does any one have a good idea about that? I am looking for a really simple and cheap method. At the moment I am thinking of construction where the complete part is mounted on a podest that allows it to swing. I try to make a video of that. While watching the video in slow motion, or even looking a single frames of it I try to find out where the maximum of the motion is. When I find this I try to find out what position the disc has by looking at the marker point. I already build this. I am using the led as a marker. I simply moved it from the center to the edge of the disc. As a cam I use a web-cam ... there is actually my problem. The cam can only handle about 15 fps. That is not fast enough to get clear pictures of the turning disc. Any ideas? Or is this idea much to complicated and one of you can give me a very simple one intead?

[Da_Fudge]

cool! I want one!

[frickelkram]

Just build one ... :-)

[alfonso]

That will be awesome with the POV clock!

[T3h_Muffinator]

Sweet! I can't wait for the POV/clock on it either!

[Bongmaster]

looks good so far :)

[zachninme]

Thats awesome! Can't wait to see the POV on it!

[GorillazMiko]

i agree with lebowski, nice job!

[lebowski]

Nice job!