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Making better and more precise...

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Sourcegeek

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Hi!
I'm working with a cheap homemade laser projector that uses 2 hard disks actuators, works with sine waves and I am trying to make it so better and precise as I can.. I know i can't do much to make it precise because they are very open loop motors, but i'm trying to get the better results.

For the start, i want to know.. What i need to do for make a circle? I mean, between which frequencies should I get a circle? I think i need to play these frequencies and then adjust the rubber bands to get the circle...

Thanks for all!
 





2 sine waves at the same frequency from function generators one leading by 90 degrees in theory should produce a circle.
 
carmangary said:
Why not just spend the $80 and get a cheap pair of galvos?
Click to expand...

Because i don't have $80 :)

NetGod3Com: I tried to get the circle with same frequencies but is a little hard to get it adjusting
the rubber bands, so I will adjust a little the wave generator. Thanks!
 
Sourcegeek said:
Hi!
I'm working with a cheap homemade laser projector that uses 2 hard disks actuators, works with sine waves and I am trying to make it so better and precise as I can.. I know i can't do much to make it precise because they are very open loop motors, but i'm trying to get the better results.

For the start, i want to know.. What i need to do for make a circle? I mean, between which frequencies should I get a circle? I think i need to play these frequencies and then adjust the rubber bands to get the circle...

Thanks for all!
Click to expand...

All you need to make a circle is one small motor... with a mirror that is
not 100% perpendicular with the motor shaft. Then shine a laser
on the mirror while the motor is running and you will get a refected
circle on a wall...
The effect is also known as the time tunnel if you have some smoke
or fog in the room..


Jerry
 
Last edited:
lasersbee said:
All you need to make a circle is one small motor... with a mirror that is
not 100% perpendicular with the motor shaft. Then shine a laser
on the mirror while the motor is running and you will get a refected
circle on a wall...
The effect is also known as the time tunnel if you have some smoke
or fog in the room..


Jerry
Click to expand...

Well, the question was how to use the HDD actuators to scan a circle, not how to make a circle.

Open loop motors aren't exactly known for their precision; you can't get much out of one. Then again, it's a good start. Consider moving up to a set of 20kpps galvos soon. :P

In any case, the circle drawing signal is two sine waves, 90 degrees out of phase in relation to each other (or was it in phase with each other)? Either way, it's one of those two.
 
^^^ that is true. but in my experience people some times dont think of the easiese solution to a problem first. that is a lot of work to do a circle. if you notice in the op that scanning isn't what he is trying to achieve. and if you read the OP's 2nd post he says he doesnt have the money for galvos.

michael.
 
chipdouglas said:
^^^ that is true. but in my experience people some times dont think of the easiese solution to a problem first. that is a lot of work to do a circle. if you notice in the op that scanning isn't what he is trying to achieve. and if you read the OP's 2nd post he says he doesnt have the money for galvos.

michael.
Click to expand...

Well, I didn't say he had to move up. I was just suggesting it as an easier solution, simply because they have feedback.

In any case the OP wants to do more than just draw a circle. If he wanted to just draw a circle then the tunnelgun would be fine.

In this case he's actually wanting to scan a pattern using the HDD actuators (in this case, a mere circle). Of course, that could be done with a tunnelgun, but you really can't do more than just a circle beyond that.
 
in his case i would recommend a 3 or 4 motor spiro with a pot for each motor


michael.
 
goninanbl00d said:
Well, the question was how to use the HDD actuators to scan a circle, not how to make a circle.

Open loop motors aren't exactly known for their precision; you can't get much out of one. Then again, it's a good start. Consider moving up to a set of 20kpps galvos soon. :P

In any case, the circle drawing signal is two sine waves, 90 degrees out of phase in relation to each other (or was it in phase with each other)? Either way, it's one of those two.
Click to expand...

The 1st post actually reads....
For the start, i want to know.. What i need to do for make a circle?
Click to expand...

So I gave a simple inexpensive way to make a circle...:beer:


Jerry
 
Yeah but he has been at this hard disk galvo experiment for some time (and threads, too) now,
I think the circle on the wall is not his ultimate objective, I think he just wants to calibrate
his DIY galvos with a circle....

A tunnel gun is useless to him.
 
i think before we all start arguing and assuming what the op wants, we should wait for him to reply.

michael.
 
Thanks for all your replies, but, anselm found my real problem :)
I think the circle on the wall is not his ultimate objective, I think he just wants to calibrate
his DIY galvos with a circle....

A tunnel gun is useless to him.
Click to expand...
 
The topic is solved, but not my problem :)
That's not solution for my problem, its a little hard because i'm using different voltages for each amp, so.. It is not a perfect circle haha..
I'm planing to do a simple lasershow with help of Adobe Audition or any other, so, i need to calibrate the channels to get a more precise shapes =/

Do you know any other software for generating sounds or frequencies? Thanks :)
 
I think LFI works with audio. Look at the first topic in this forum for how to rig up something with a sound card.
 
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