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Propeller clock operation

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POV displays are very common projects. If you search POV display or Persistence Of Vision Display or Clock, you'll find a lot of projects like this. They are pretty simple. A 16f877a would work fine.
 
Dear Kubeek

Thanks for the reply,
I have enough experience with PIC to handle the project with your advice

Please advice

Thanks in advance
 
I advice you to read the project in the link under the video, then maybe google some more similar projects and ask what you don´t understand.
You know, this is not a lecture so I am not going to write a huge post about everything that comes to my mind.
 
Dear All,
Thanks for the reply

Can I have the theory behind the calculation of LED "ON" and Motor speed

Please advice
Thanks in advance
 
It's very simple, if you need to divide the full rotation by X "pixels" you time the period of one rotation using the sensor.

Then you divide that period by X and generate small periods, each period is one "pixel" or "pixel row".

It is easier if you don't need to fill one complete rotation, if you are happy with just some of the rotation being lit up you just start making "pixel rows" after each sensor pulse, and run the motor at a sufficient speed.
 
Dear Mr RB,
Thanks for the reply

It is bit hard to understand. can I have more simple step by step explanation with link

Your help would be highly appreciated

Thanks in advance
 
Dear All,

I decided to use PIC18f2550 for my first POV. Is it correct selection

please advice

Thanks in advance
 
Start with a clock...

Howdy, then go after something interesting... TEXT. I built my first ceiling fan text display in '03 (monochrome, color in '05). When blade sweep matches text sweep, fairly trivial. When opposite, Not Trivial. Next throw in real lower case descenders... if that doesn't stretch some gray matter, thou art a better man than I. See attached time-lapsed images. Video recorded sequences alias out as blades being static... too funny.

Software accounts for rotation direction & speed, including speed changes (direction chg req's power down {duh}). Changes message & colors on # rotations as programmed by a VisualBasic Windows app. Upload is by RF, 32 characters upper & lower, 16 messages, 24 colors, limited by ram in uCs available in '04.

A fun project, wish I had time to pursue/improve/market it. The "cab3" image is a portable/suitcase version that is its' own stand and folds up into a triangular case. The blade attached is the one with all the circuitry.

P.M. me if you are a valid & interested candidate for taking this over as a project, I simply don't have time. I can work with someone, but not lead. TNX <<<)))

P.S. this not intended to be a solicitation OR a thread hijack, but I've been sitting on it for 7+ years. It's stupid to not make it available to an interested, valid concern. <<<)))
 
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One of the difficult things with a pov clock is powering the display, the display needs power for the micro and the leds, but because it rotates you cant just connect wires to it.
The second vid uses a video head as the motor and I suspect power coupling, I've seen a couple of projects where the transformer coupling found inside a video head that is normally used to couple video signals back to the vcr repurposed and driven with something like 100kc squarewave and used as a rotary transformer to power the display.
If I can find the link in my favorites I'll post it.
Edit: found it, looks like your second vid https://us.cactii.net/~bb/propclock/index.html
 
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After reading all this I dug out my old hard drive and started looking for a simple motor controller for it I found a great link to one you may want to have a look **broken link removed**
There some good stuff on that page

Here a link to the circuit **broken link removed**
 
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Thats an interesting link burt, I've looked at driving a hdd motor before, using a micro is complicated, the only drawback with that circuit is that it only drives the one coil, I've seen a simple discreet component driver for a brushless motor using just mosfets and resistors but cant find it anymore.
Still might have to have a go with that circuit, I've plenty of scrap drives and a couple where I've robbed the servo for other projects.
 
be80, I'm working nites at the moment and I just tried the circuit you linked us to.
It works, and its good fun, I didnt have a 22nf cap so I've used a 100nf, I have half a drive (I sawed off the servo movement for another project) on the bench doing 18krpm with some serious gyroscopic effects, I'll try with the correct 22nf caps when I get home, I suspect it'll probably try to go much quicker.
Totally useless but its a laugh.
 
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I tried a 3 phase driver using a pic but realised it'd take a lot more than a few lines.
 
I tried it like this **broken link removed**

But never got the speed right.
 
Yes seen that sort of line before, but doesn that not have any feedback, the motor just runs synchronous, then its very easy to lose lock and everything goes pants.
It seems to me that the only way to get the speed and power a motor can deliver is to have some sort of feedback.
You can do it using the a to d and a load of algorithms, thats where I got fed up.
The simple version I just built though could be easily built into a pic, in fact you wouldnt need software to run it the chips comparator would do everything needed.
Maybe theres an inbetween, perhaps miss out every other phase drive to get feedback, still driving all phases.
Better not hijack this thread now.
 
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