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LAN_403

lpfthings

Sun Jul 05 2009, 09:29AM

Registered Member #1361 Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305

After playing with the simple mirror on motor setups, I decided I needed something a little more powerful.

I started with this set of Galvo's (Galvanometers)

and a bodgy little 40mw green module from an old laser scanner I had.

Well I had the basis of my scanner together, but now I needed something to control it with. The galvo's came with a DMX board which had a few preset patterns, and I used that for quite a while. Eventually I got bored with it, so decided get a DAC. The cheapest DAC I could find was about $500, which was out of my reach at the time, so I went for a DIY solution.

I bought a 5:1 channe sound card off eBay for $12, and a opamp board from a member on another forum. The sound card is essentially a DAC itself, but to make it suitable for laser use, the AC coupling capacitors needed to be bypassed, and the signals corrected a bit. The correction board consists of a few opamps and trimpots, so you can adjust the offset and the max signal voltage.

100 6904

The galvo's require a +/-5V differential signal, but the sound card was only single ended. No worries, it just means I wouldn't be able to scan as wide. So I put together my sound card DAC:

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So I mounted the laser and galvo's into my old scanner case, connected the DAC and off it went! I was amazed and was up all night watching it. I decided to try display some graphics on it, and they looked really, really bad!

So I ran some test patterns up:

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I compared it to other peoples, and found out just how terribly tuned these scanners were.

I decided to just ignore it, since I could not afford anything else, and it was cool!

I decided to grab the fog machine out one day, fired it up and went to watch a show. Started the laser show, I heard noise, but no light!
I quickly turned the scanner off and pulled it apart, and sure enough, the laser was dead. Damn!

I contacted another laser enthusiast, and he sold me a 2nd hand laser module for a nice price. I installed it and off I went again. It worked for a few weeks, but I had noticed it getting duller and duller. This laser was supposedly rated at 150mw, so I tried focussing it down and burning something. Nothing, not even a puff of smoke!

I couldnt send the laser back, since it was already second hand and wayyyyyyy out of warranty, so went looking for another laser module.
The previous guy contacted me again and told me he had a nice small unit in storage he'd sell to me cheap, and he measured it in at around 190mW! After hearing that, I sent the money, and 2 days later it was here!

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The power supply for this laser was HUGE, and would no longer fit into my previous case, so I bought one of these

Meanwhile, I found a sale on some better galvo's, and after seeing the test pattern on these things I was really wanting something a little better. I scraped up some cash, and bought them. They are rated at 25Kpps @ 8 degree's. I got a piece of aluminium, milled it to fit in my case and started mounting stuff to it.

I cut the holes in the case, and mounted the laser and board inside:

And a bit of paint on here would do just nicely:

I went to connect my sound card DAC and noticed the laser wasn't modulating. So I did a check over the sound card, and the output was floating at -2V, and the little chip on the sound card was toasty. Well, there goes that sound card! :(

By then I was annoyed I couldn't test out my new scanners, and decided to start saving for a better DAC.

A few weeks later, I placed my order, and it arrived ...

This thing is the size of a credit card!!! It has DMX and USB input, in that teeny package.

I decided that $500 sitting out like that was a little unsecure, so after 4 hours with a needle file, I finally got it boxed up:

Well it was time to fire it up!

I connected everything, installed the software and proceeded to make some test patterns:

AWESOME!

I had to turn the laser down for the picture, since it over exposed the camera too much, thus the dotty lines.

I couldn't leave it there, so I ran up some random logo's, which can be found here to save posting them all on the board:

(They were done with the Moncha program, which was lent to me, not the little red DAC you see above.)

I was pretty impressed, so I put a few shows on YouTube aswell:

And a show I made myself:

A while ago when I still had m soundcard DAC, I bought a mini ITX board (1Ghz) so I could run it remotely. I finally got a chance to hook it up and try it out, and it works flawlessly via wifi and remote desktop.

It has a 2GB CF SSD, so it can't store much, but still works. There's a outline of it here

with my really bad camera skills :P

Not really a current project, although I am continually working on it, and thought I'd might as well share :) If some members want, I have been offering to write out names etc for them with it, I'd be happy to do that for anyone here as well :)

Cheers,
Dan ;)

...

Sun Jul 05 2009, 05:27PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

That looks like quite a nice project! But it definitely needs more color

I am not sure if you have seen it, but you might check out my projector

and

you think your galvos are bad, look at the ones I am working with

They are good for about 5pps, anything higher than that the edges start to get rounded off. Which on that note, I would love to trade your old set of galvos for some red or blue modules or dichros for combining them in with your green.

Cheers!

lpfthings

Mon Jul 06 2009, 12:10PM

Registered Member #1361 Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305

I was looking over your project before I posted this, it's what gave me the inspiration to post :)

I would consider selling the galvo's, although the humidity here has got to them. They have a small amount of surface rust on the back, and one of them twists from the base, I would feel kind of bad trading them in that condition.

They are still fully functional, just a bit dodgy is all.

teslaguy

Tue Jul 07 2009, 06:27AM

Registered Member #617 Joined: Fri Mar 30 2007, 07:29PM
Location: Buffalo NY
Posts: 49

I dont mean to spam but I must say that you did a most excellent job.

Conundrum

Thu Aug 06 2009, 08:13PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

hmm. if it helps I can probably spare a slightly toasty (works, output window cracked but still lases in the aixis module) 15mW HD-DVD laser, PM me if you are interested.

$20 gets it sent as is, no warranty whatsoever either suggested or implied, to get the diode to fit was a a first class kludge of epic proportions and breaking the window was caused by sideways pressure on the diode. I removed the damaged casing and the diode still works.

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