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Magnet needed?

by flamingfun on Tue Feb 05, 2008 7:42 pm

I want to use these in a night club for a dancer to spin around. Can i use them for this? Will they work without the magnet? Any ideas? thanks!
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by adafruit on Wed Feb 06, 2008 12:50 am

as the firmware is currently programmed, yes a magnet is necessary.
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by kayrock66 on Fri Feb 15, 2008 2:06 am

It could be done, but not easily by an electronics novice.
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Any suggestions where to start?

by flamingfun on Sun Feb 24, 2008 6:10 pm

Any suggestions where to start?
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Poi

by kayrock66 on Tue Feb 26, 2008 12:18 am

You're talking about poi dancing right? The easiest thing would be to just run the lights at a fixed speed and make the spinner synchronize his/her spinning with the speed of the lights. If the pattern rotates one way he/she is going to fast, if the pattern rotates the other, too slow. They'd get the hang of it pretty fast.
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by cablemonkey on Sat Jul 26, 2008 2:35 am

replace the hall device with a basic 555 oscillator
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by kayrock66 on Sat Jul 26, 2008 5:38 pm

If you were familiar enough with the firmware it would be pretty easy to do.
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Re: Magnet needed?

by Thunderhunter on Sun Nov 09, 2008 9:29 am

[color=#FF8040][b] I would like to install the SpokePOV on the cars hubcaps , but I don't want to mess with the magnet, so how could I replace the hall effect sensor with an oscillator. I don't mind if the image on the wheel is going to be clear only at a certain speed let's say 40 miles/h.
I would really appreciate if someone would tell me if the image attached below is correct excluded the hall sensor and where can I mount the oscillator. Istvan[/b][size=150][/size][/color]
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Re: Magnet needed?

by Thunderhunter on Sun Nov 09, 2008 9:38 am

[b] I would like to install the SpokePOV on the cars hubcaps , but I don't want to mess with the magnet, so how could I replace the hall effect sensor with an oscillator. I don't mind if the image on the wheel is going to be clear only at a certain speed let's say 40 miles/h.
I would really appreciate if someone would tell me if the image attached below is correct excluded the hall sensor and where can I mount the oscillator. Istvan[/b]
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PCB10.png
I would really appreciate if someone would tell me if the image attached below is correct excluded the hall sensor and where can I mount the oscillator. Istvan[/b]
PCB10.png (255.31 KiB) Viewed 3804 times
some difficulties with the programming
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Re: Magnet needed?

by The_Don125 on Sun Nov 09, 2008 12:14 pm

Not so sure about the image.

Anyway, about using an oscillator, you could probably use a 555 timer, just set the 555 up in astable oscillator mode, and connect the output pin to the pin formerly used as the hall sensor's input. You may need to play with the 555 a bit to get the high time as short as you can for reliable detection, while not leaving it too long that you get false readings.

You'll need to adjust the 555's oscillation frequency to go along with the speed you want to travel. Assuming 24" diameter tires, 40 mph comes out to about 9rpm

As for where to mount it, you'll probably be best off making the 555 circuit on a separate board, and then gluing it to the backside of the spokepov board.

This is all assuming the SpokePOV is structurally strong enough to withstand travel at 40 mph. It was designed for a bicycle after all, so 40mph might involve the thing flying to peices on the road (and a few angry drivers as a result, those chip legs are sharp, wouldn't want one of them in my tire)
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Re: Magnet needed?

by Thunderhunter on Sun Nov 09, 2008 2:16 pm

thanks for your quick reply "The_Don125",
don't worry because of the shattering of the pcb, I live in the freezing transylvania so probably we not gone meet on the road, we have no highways here so speed is slow and I will mount the whole thing under the hubcap so even if it falls a part it's gone be in the rim. I work like an industrial designer I don't know much about electronics, could you please inform me exactly which parts do I need for this 555 oscillator or send any pictures how does this thing look like ? Istvan
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Re: Magnet needed?

by kayrock66 on Sun Nov 09, 2008 3:25 pm

You have 2 approaches
1) Add to circuit to fake hall sensor signal, leave software as is
2) Add to software, leave hardware as is.

So depends on which one you're more comfortable with. The SW approach is cleaner.

I think the limited speed range thing is going to be awkward. But come to thick of it there are probably are some patterns that will make neat designs at any speed. Not pictures or words but, by Spirograph style designs. Start with putting in a sinusoid or triangle wave.
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Re: Magnet needed?

by Thunderhunter on Tue Nov 11, 2008 11:17 am

Thanks kayrock66 for your answer,
I rather leave the software as is, so I prefer changing the circuit if it is not so difficult because I will probably redesign the whole pcb to make it lighter and more balanced . Could you please explain me how do I change the hall effect sensors wiring on the attached image above , Istvan
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Re: Magnet needed?

by kayrock66 on Wed Nov 12, 2008 12:13 am

Look up some example circuits using a 555 timer. If you pick the CMOS version of that chip, you could probably power it from pin jsut like the current hall sensor is.

They'll have a formula to pick the component values to set the frequency. Pick your frequency based on the revolutions per second of the wheel for the speed you want to target.

I think what you really want is a design that doesn't need a hall sensor yet will still synchronize with the wheel rotation.
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Re: Magnet needed?

by The_Don125 on Wed Nov 12, 2008 12:43 am

kayrock66 wrote:I think what you really want is a design that doesn't need a hall sensor yet will still synchronize with the wheel rotation.


What about using IR detection? You could put an IR detector in the place of the hall sensor, and an IR light source under the wheel well. Every time the spokePOV passes under the IR source, the detector will trigger, and the spokePOV will work as normal, you might not even have to modify the code!
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