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POV using LED matrix Answered


I am doing a project of making and LED analog clock. The clock contains almost 300 LEDss and they are arranged in a specific pattern that looks like and analog clock.

My question is how would you create a POV in this design of the clock. I have checked other projects of POV; in those projects the whole device moves along with the row of LEDs and then it created a POV effect. However, in my project, the LEDs are fixed on a plastic sheet. How would I create a POV effect on that???

Please HELP!!!

4 Replies

caitlinsdad (author)2013-01-26

I think the correct term is to put some animation to the LED display like have it resemble the hands of the clock sweeping around the dial by only lighting up the LEDs in your fixed matrix. That would not be POV. In general, the way to animate or computer control a matrix/grid of LEDs is to be able to turn on each and every pixel or LED individually. Look up charlieplexing and some of the arduino projects to control it. Good luck.

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Orngrimm (author)2013-01-24

I am unsure on what you made... Are your LEDs arranged like the rays of the sun? So every "ring" has the same ammount of LEDs but with increasing distance from the center the distance betwheen the LEDs increase?

If so, then you can make it relatively simple.
Just control them as 2 rings: Inner lets say 4 LEDs and the outer lets say 4 LEDs.
I will call those 2 groups rings in the future text.
For the rest of the text i suppose you have 12 rays (one for each 5 minutes).

With a microprocessor, you make a simple LED-matrix with 12X and 2Y.
The minute is always ring 1 & 2 in the Y and the corresponding ray in X.
The hour is only the ring 1 in Y and the corresponding ray in X.
So unless your minute-dial and hour-dial are over each other you will have 3 segments lit:
1 outer segment (ring 2) for the end of the minute-dial.
1 inner segment (ring 1) for the start of the minute-dial.
1 inner segment (ring 1) for the hour-dial.

However, your resolution is a lot less than if you do a moveable POV since you can control / time the moving part more precise than you can pack your LEDs.
If you can control / time the movement by 1° you would need 360 "LED-rays" consisting of lets say 8 LEDs each giving you a total of 2880 LEDs. And in the center the LEDs would be so densely packed the ring (with 5mm LEDs) cannot offer them enough space if you want a reasonable sice or your smallest ring would be 57.2cm in diameter to give 360 5mm-LEDs some space.

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Bam Boy (author)Orngrimm2013-01-26


yes the design is like a sun. The distance increases as the LEDs move further from the center. Also, I have separate rings for the minutes and hours.

--> The inner most circle is for hours. It consists of 12 rows of LEDs and each row has 5 LEDs inside it. They point towards the hours.
--> Then comes the minute circle. It doesnt go all the way to the center of the clock. It starts from the edge of hour circle till the boundary of the clock and it has 20 rows of LEDs and each row has 6 LEDs in side it.
--> and then the outer boundary consists of 60 LEDs for the seconds that are going to blink with each second.

The problem that we are facing is that the LED matrix is not in a compact form to create POV. Like in different other projects they have LEDs tightly compacted. But we got spaces between LEDs.

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Orngrimm (author)Bam Boy2013-01-26

Yes. Thats why a POV normally incorporates a moving part like a slit in a harddisc-platter or such stuff...

As i see it, you dont even need a microprozessor...
Just 3 shift-registers:
one with 12 places for the hour
two with 60 registers for the minutes and seconds.

The overflow of the seconds push one of the minutes; the overflow of the minutes pushes one of the hours...

Honestly: I dont understand your question. What exactly is the problem with the POV? With a fixed panel of LEDs you cannot make a POV in the classical sense... It is simply not possible and defies the idea of POV: a small moving thing which creates an illusion of fluid movement triggered to a certain position in time and space.

Are you asking how to pack LEDs tighter or what? I dont get the question...
Someone of the others can push me on the right track?

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