pov clock rpm selection

[Disha Karnataki]

hey people i want to do a pov clock so i am going to use 500rpm motor.Is it fine if i use 500rpm??

 

[jayanth.devarayanadurga]

You can use it.

 

[Disha Karnataki]

so i guess 200rpm is the minimum limit right??

 

[jayanth.devarayanadurga]

I don't know about the minimum. But if it is too slow then it is not good. You will not get proper display for slow speeds.

**broken link removed**

Use flexible PCB and SMD LEDs and a good motor which makes less noise.

 

[paulfjujo]

hello,

To define RPM, is not so easy because many other parameters enter in final results.
What is your mechanical design ?
How many leds ?
Size of matrice of characteres ?
Fixed message, or scrolling message ....
... clock of microcontroller
at least software treatment .


You want to use all circonference or only a view angle ?

Persistance of vision is linked to the duration of illumination .. an brain reaction.
supose you have a circle of 1m of diametrer and led situation at the border of circonference,
Necessary RPM will not be the same as if you have a diameter of 10 cm
because linear speed is important to define How long time you will see the leds
and memorize what you brain has record..

If you start from scratch, you will have a lot of work, but very interessting and instructive.

you can see on my webpage an example of POV clock ,not based on RPM, but on Oscillations.
Frequency of oscillation is not so high to obtain some results.

 

[Disha Karnataki]

yes i want to do it from scratch.
I actually intended to make a scrolling fixed message display as it is more good to start for a project on POV from scratch.
actually i don't know how to start with but i will tell u the specifications as below:
microcontroller-8051 with 11.0592Mhz frequency.
i am not sure about the motor rpm but as i have started writing the program i have written a part of the program in assembly considering rpm to be as 500rpm..
so please guide me here. i have still many more doubts like :
i read about the POV's on net and, it was told that we should know width of the pixel used how to find this out??? Do they mean we must know size of LED or what is it???

 

[paulfjujo]

hello,

Yes, you must first define some data:
-Alphabetique car or grafic car
- how many leds for the colum car (usually is 8 for alphabetic ) or ?
- what matrix of car (usually 7x5 for alphabetic ) or 8x8 for graphic or 16x16 ..or other !!
-how may car on the viewing angle ?
-what is the value of viewing angle (less 360°!!)
- led size ..dia 3mm , 5mm, 8mm or CMS ?
example:
"MY MSG IS 16 CAR"
view angle 120°
example if i use 600 rpm (more easy for calculations)
if 600rpM => 10 RpS => 0,1sec per tour 100mS for 360° 33mS for 120° or 16 cars

1 alphabetic car is defined in a matrix 6x8 only 6 pixel for the car +2 pixel inter-car
Pixel clock becomes : 33000µS / (16x8)=257µS
Another important item is Synchro Tour.. a sensor to define start of one tour
and software is synchronised from this top... + 275µS to center the view

What is your mechanical design ?

 

[ard]

500 rpm is too slow for a good flicker-free display. Your display at 500 rpm would get refreshed just 8.33 times per second, just not good enough for a nice flicker-free display.

Also, remember your rotating pcb is going to pose a weight that would reduce the actual rpm of the motor.

I would choose a motor that gives at least 1200 rpm, with the load.

Regards,

Anand

 

[Disha Karnataki]

hello,


-how may car on the viewing angle ?
-what is the value of viewing angle (less 360°!!)
view angle 120°
1 alphabetic car is defined in a matrix 6x8 only 6 pixel for the car +2 pixel inter-car
Pixel clock becomes : 33000µS / (16x8)=257µS
What is your mechanical design ?

i dinot get the concept of ""viewing angle"". can u explain a bit in detail.
mostly mechanical model i will be using is a single strip of LEDS may be 16 leds in a single column. so it's matrix of 16x1 am i correct??? ok i donot know the pixel of led nor does the electronic shop seller knows so can u tell me how did u find that??

 

[paulfjujo]

Viewing angle : you want to see all around 360° ? or only in front of the POV device ?

motor speed is only one element of the puzzle..
considere also diameter .. because VL=PI*D*N , linear speed of the strip of led, in front of your seeing .

I think you have to read more deeply, existing POV appliication on the web..
Show your mechanical POV device, after you can get some help..