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laser display build prob.

 
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gelo
HG Junior


Joined: 01 Feb 2007
Posts: 20

PostPosted: Sat Mar 31, 2007 5:11 am    Post subject: laser display build prob. Reply with quote

hello all,

im currently in the mkaing of a cheap laser display to try and prove the concept that you can get quality drawings and only needs to cost about 15 to build it, which i need some advice on.

i got to the stage where i have an op amp, two motors (they are suitable i think) and a signal input and power input. I got me a laser aswell but that dont matter now). i would like to know what is the best way to get accurate movement from the motors as i'm using the audio signal from my pc as a reference source, but at the moment all the motors do is move when the voltage changes from the signal. So how do I go about converting the analog signal to a variated DC signal? I saw an article on the net and it used an op amp. Is this the best choice or have i wasted 50 pence on a dual channel op amp?

website i found the article on

http://www.allaboutcircuits.com/vol_3/chpt_8/7.html

if oyu would like more technical info i would be glad to help...
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Alan
Site Admin


Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB

PostPosted: Sat Mar 31, 2007 2:11 pm    Post subject: Reply with quote

I would have a look at this article, I am not sure is a normal DC motor would be able to driven with a strong enough AC signal to constantly reverse direction fast enough to draw an image without burning out.
http://hackedgadgets.com/2006/07/10/home-built-laser-projector/

Do you have some physical mechanism that restricts the revolution of the motor past 180 degrees or is it free spinning? If it is free spinning you would be able to generate cool looking swirls but since you have no idea where the beam would be positioned there would be no way to draw an image.

Keep up informed on the progress. Smile
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gelo
HG Junior


Joined: 01 Feb 2007
Posts: 20

PostPosted: Sun Apr 01, 2007 3:04 am    Post subject: Reply with quote

Alan wrote:

Do you have some physical mechanism that restricts the revolution of the motor past 180 degrees or is it free spinning?
Keep up informed on the progress. Smile


ive done a little research into the movement and the real galvos only move at a range wich is about 10 degrees either way, so only the strongest of current will make its over run but seeing as im converting a 400 mV AC average to a 0 to 5v Variating Direct Current source the should only move slightly on a small amount of current. even tho my motors are:

RF-300C-11440

hmm with the link i see that guys galvos are inverted, i.e. the windings are on the outside, might need to find some dynamos...

Alan wrote:
I would have a look at this article, I am not sure is a normal DC motor would be able to driven with a strong enough AC signal to constantly reverse direction fast enough to draw an image without burning out.


me has a heat sync lol but as they dont move too much they dont get incredibly hot, i thought first of all they had to have some voltage going through but they dont. I tried that and almost burnt my hand lol. Proper ones yes they had atleast 25v ptp but im designing these so its possible for a small audio signal from a wav file to be used or somthin lol.
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