# The Challenge: Home-Made Laser Show for Under $700



## ambassador (Mar 16, 2007)

Using a typical laser pointer as the light source, a cheap notebook PC, some off-the-shelf components, and some free software; it is possible to assemble the equipment capable of displaying via a laser beam any text-based message on a wall at a distance of 14 feet - all for less than $700. 

That is the theory. That is also the design challange to the members of the Candle Power Forums. 

Just to get things going, here are a couple of possible parts to initiate the parts list. 

1. Red Laser Pointer - $24 
http://www.atlasnova.com/RedLaserPointer635nm.htm 

2. Cheap Notebook PC from Pawn Shop - $100 

3. ... 


Of course, I am interested in making this thing too! Further, the theory indicates that this equipment will be capable of projecting some simple vector-based graphics in addition to any text message.

Ambassador 
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## allthatwhichis (Mar 16, 2007)

The key will be your scanners and DAC. You can get a DAC on eBay for fairly cheap, <$100, that will work for popelscan which is free. It's ghetto, but free.  I'm using it at the moment. You then need a set of scanners. I think there is a 20k set for <$300... These prices are off the top of my head, I may be off a little. I'll post some links a little later when I can look for them. That red laser pointer isn't going to blank so you will have lines connecting each letter in your text. You could always build a driver for it though...


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## ambassador (Mar 17, 2007)

If 'blanking' is what eliminates the lines that would otherwise connect the text, then we must have blanking for this challenge. So, if the referenced laser pointer cannot 'blank' then we must use a laser that can blank. Thank you allthatwhichis for setting this challenge on the right course with regard to the light source. 

Also, your forthcoming links to parts will be most appreciated! 

Ambassador 
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## abeland1 (Mar 17, 2007)

I doubt that you will find any laser pointer with a built in ability to blank. Both my 650's and 635's are undoubtedly using a current mirror circuit to regulate the current to the laser diodes to compensate for varying battery voltages. See the following. http://www.allaboutcircuits.com/vol_3/chpt_4/12.html
The modules on the red pointers should come out with much less trouble than the greenies. I am sure there is a plethora of electronic technical ability on the forum to find a way into this circuit to cut off the supply of current to the diode with a standard TTL input. Remember that the case of the module is positive. Let's have a little fun with this. Here's the deal. The first three members of the forum to volunteer for the project will receive two 650nm pointers, one to blow up, and another to end up with a working unit. Publish your results on the forum and allow the members to vote for the best solution. The winner will receive two 635nm pointers and 1 5mW atlasnova green with a nice big MCA. Let the game begin.


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## stevetexas (Mar 17, 2007)

Abe - that is a generous and tempting offer. I'd love to take you up on it but am afraid I don't have the technical skill to make it worthwhile. 

I think we should leave this up to the members who know a little more and have more technical skill


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## Aseras (Mar 17, 2007)

abeland1 said:


> I doubt that you will find any laser pointer with a built in ability to blank. Both my 650's and 635's are undoubtedly using a current mirror circuit to regulate the current to the laser diodes to compensate for varying battery voltages. See the following. http://www.allaboutcircuits.com/vol_3/chpt_4/12.html
> The modules on the red pointers should come out with much less trouble than the greenies. I am sure there is a plethora of electronic technical ability on the forum to find a way into this circuit to cut off the supply of current to the diode with a standard TTL input. Remember that the case of the module is positive. Let's have a little fun with this. Here's the deal. The first three members of the forum to volunteer for the project will receive two 650nm pointers, one to blow up, and another to end up with a working unit. Publish your results on the forum and allow the members to vote for the best solution. The winner will receive two 635nm pointers and 1 5mW atlasnova green with a nice big MCA. Let the game begin.



afaik you just need to add the ttl to a pointer. you simply interrupt the circuit with a transistor when voltage is applied.

http://www.siliconfareast.com/ttl.htm

edit:

you might even be able to incorporate this to be added to a pointer using a circuit say inside of a disc you place in before the batteries. you might be able to do with with the ttl input voltage and a magnetic switch to basically open the circut before the batteries without modifing the pointer wiring at all.


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## dr_lava (Mar 17, 2007)

Hey, this is a great thread! I do hope we are successful even at a lower price, especially if it's only 1 color, but this is a good start. 

It's possible that an aixiz laser module http://mfgcn.com/_wsn/page2.html (although still without blanking) could be modified more easily than a pointer laser. In fact, I have an opened 635nm module sitting in front of me now that they sent me a bit ago as a sample.

Still, it's hard to turn down a free laser offer, I'm up for the abeland atlasnova challenge!


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## abeland1 (Mar 17, 2007)

dr_lava said:


> Hey, this is a great thread! I do hope we are successful even at a lower price, especially if it's only 1 color, but this is a good start.
> 
> It's possible that an aixiz laser module http://mfgcn.com/_wsn/page2.html (although still without blanking) could be modified more easily than a pointer laser. In fact, I have an opened 635nm module sitting in front of me now that they sent me a bit ago as a sample.
> 
> Still, it's hard to turn down a free laser offer, I'm up for the abeland atlasnova challenge!


PM me your address and they will be on the way.


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## sysadmn (Mar 17, 2007)

Dang, wish I had the time...
I suspect the 14 feet would be the hard part. It can be hard to paint the surface often enough to get a good solid line. Here's one that used an AVR microcontroller and 16 mirrors, but seems to have a throw of about 2 feet:
http://heim.ifi.uio.no/haakoh/avr/







Some links from when I researched this last year, courtesy De.licio.us:

If you think it's hard today, image what it was like in 2002:
http://web.media.mit.edu/~stefanm/TinyProjector/index.html

DIY Laser Show, including homemade scanners
http://elm-chan.org/works/vlp/report_e.html


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## stevetexas (Mar 17, 2007)

Abe -- you rock -- this is what is great about the forums.  

Please PM me about a laser. I haven't bought from you before but WILL buy now since you're such a great supporter. Looking for a reasonably hi-power green or red.


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## ambassador (Mar 17, 2007)

Here are a couple of links which are very relevant to this challenge. 

http://spt06.chez-alice.fr/00/scan1.htm 

http://www.skyfirelasers.com/boomdog/byoshow2.php 

Ambassador 
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## allthatwhichis (Mar 18, 2007)

Well, I'm at work and can't access eBay, but I will toss out the other place I type a lot at that has TONS of information about this... You may even call it a cheat. Photonlexicon.com has only a few members but we ususaly only talk about laser shows, mainly ILDA compatable projectors but DMX and generic ones also. There's also a link to the 20K scanners I was speaking, but those are DMX controlled and may need a thing or two to work with a ILDA DAC. I don't "THINK" so but am not totally sure.



I'd have to ask the seller who is a member at PL. I'll do a thourough search when I get home around 5am EST tomorrow. :candle:


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## ambassador (Mar 18, 2007)

As another CPF member suggested earlier in this topic, the $700 limit may be significantly greater than needed for this challenge. Look what $650 gets you - already made and delivered to your door.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110101895837&ru=http://search.ebay.com:80/110101895837_W0QQfromZR40QQfviZ1

Ambassador 
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## allthatwhichis (Mar 19, 2007)

Well... that's a piece IMO... AND it's gonna cost $120 to ship it here. That's splittin hairs I know but it IS a challenge right?  Gimme a few and I might be able to make it off eBay... 

O and you need software, and probably a DAC, that ILDA port is probably only the connector for AFTER the DAC.


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## allthatwhichis (Mar 19, 2007)

8 bit DAC kit $33
10mW TTL Greeny=$80
20k scanners/galvos w/dmx board=360.00
New link for popelscan download=Freeware

We'll need that 15v power supply for the DAC, but who knows how much that'll cost. I've ran around town for a damn 12volt and had to spend $15 at a radio shack 30 miles away... so we'll be generous and way $20 All that above is shipped... $493.00 If you can find a cheap 30 to 60mW red you can take this optic=$22.50 and get RGY text...



possibly for less than $700.  I bet you could get a 40 to 50mW out of a CD burner... :lolsign:


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## abeland1 (Mar 19, 2007)

allthatwhichis said:


> 8 bit DAC kit $33
> 10mW TTL Greeny=$80
> 20k scanners/galvos w/dmx board=360.00
> New link for popelscan download=Freeware
> ...


For a power source for experimenters this could be interesting:
http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply


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## ambassador (Mar 19, 2007)

allthatwhichis - The $650 roughly included shipping (the eBay device cost $550). 

The point is that this challenge can most likely produce the goal for significantly less that $700. This assertion is especially likely given that generous folks like abeland1 are offering incentives to encourage those with the technical expertise to pursue the challenge. 

Ambassador 
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## allthatwhichis (Mar 19, 2007)

Sorry, I'm just a good eBayer...



Well, beyond missing the price there, I just thought your figure was without shipping. 

Although I've got at least $2000 in my projector. I would call mine a "budget" model too or as I like to refer to it as ghettofabulous.



I don't have any electrical skills. I can build ya a computer, program a video game, but could get you one good solder out of a dozen tries.




I actually thought you had $700 and needed to get a projector for a party or something.



I guess the above that I made up could be a rough ceiling for everyone to try and beat. The one thing I didn't include was any type of table or box. At first I used a piece of wood, actually a shelf I took off my desk. I just recently got a piece of aluminum to mount it all on, but the wood worked.


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## allthatwhichis (Mar 19, 2007)

abeland1 said:


> For a power source for experimenters this could be interesting:
> http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply


 
:bow: You're the man... I can't beleive I've never searched this. I have several of them lying around with no purpose for existing. Now they can be re... purposed..? abeland1, I have been wondering, why don't you sell plug in lasers? Meaning not handheld. We need a good, honest distributor in the US. I'm just curious.


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## Aseras (Mar 19, 2007)

abeland1 i was checking out your site and noticed this http://www.atlasnova.com/RemoteSwitch.htm

something like this seems to be the easiest and least damaging way of adding a ttl circuit to a pointer... easy to undo to just replace the endcap.

Do your reds have a real driver in them or are they just simple current limiting, or nothing at all?

I'm up for the challenge too.


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## abeland1 (Mar 19, 2007)

Aseras said:


> abeland1 i was checking out your site and noticed this http://www.atlasnova.com/RemoteSwitch.htm
> 
> something like this seems to be the easiest and least damaging way of adding a ttl circuit to a pointer... easy to undo to just replace the endcap.
> 
> ...


Keep in mind that it has to be turned on and off rapidly, as in well under a microsecond. I doubt that this approach will accomplish this, as the driver circuit will probably interfere.
The remote switches only fit the greens. Check post #4 for the rest.

----- Original Message -----


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## liveforphysics (Mar 20, 2007)

Ok, I'm in for this deal.

My plan is inspired by the link showing the guy that used speakers for galvos. Take a set of powerful loudspeakers and cut the cone material away the voicecoil, leaving just the spider/coil tension to coil centering and control. This will leave me with a very lightweight efficeint liniar electromagnetic driver. I will mount the liniar motor by the basket that used to support the suround of the cone upsidedown, and bond a thin carbonfiber tube with cynoacrolate gel through the flux gap vent hole in the bottom of the magnet, so it has a couple of inches pokeing out. This will connect to a little arm sticking off the back of a small mirror mounted on a piviot point.

One for the X, one for the Y.

Blanking will required studding the circut in the laser driver board to see how we can interupt the signal to the little NPN transistor that switches current to the diode. I'm hopeing that I can just use a PNP controled by TTL signal to control the line switching the gate on the current switching NPN that feeds the diode.

Things rarely are that easy though... Perticularly when it comes to lasers... 


Best Wishes,
-Luke


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## liveforphysics (Mar 20, 2007)

Atlasnova- I think your offer to send lasers out for blanking design research is awsome, and I would be very pleased to receive them. 

I've always loved your CPF special lasers, and I have one in my pocket as I type this. Your shipping and service has always been amazingly fast, and you and your wife are even friendly to talk with on the phone 

Best Wishes,
-Luke


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## abeland1 (Mar 20, 2007)

Aseras said:


> abeland1 i was checking out your site and noticed this http://www.atlasnova.com/RemoteSwitch.htm
> 
> something like this seems to be the easiest and least damaging way of adding a ttl circuit to a pointer... easy to undo to just replace the endcap.
> 
> ...



PM me your name and address and they will be on the way.


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## abeland1 (Mar 20, 2007)

liveforphysics said:


> Atlasnova- I think your offer to send lasers out for blanking design research is awsome, and I would be very pleased to receive them.
> 
> I've always loved your CPF special lasers, and I have one in my pocket as I type this. Your shipping and service has always been amazingly fast, and you and your wife are even friendly to talk with on the phone
> 
> ...


PM me your name and address and they will be on the way.

Anyone else up for this?


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## ambassador (Mar 20, 2007)

> Anyone else up for this?


 
Yes, please. However, if you have the complete schematic of these 'R&D' laser pointers that you have so generously offered, then just the schematic would be appreciated at this time. There is no need to send the laser pointer at this time. 

Ambassador 
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## abeland1 (Mar 20, 2007)

ambassador said:


> Yes, please. However, if you have the complete schematic of these 'R&D' laser pointers that you have so generously offered, then just the schematic would be appreciated at this time. There is no need to send the laser pointer at this time.
> 
> Ambassador
> -------


http://img.inkfrog.com/pix/abeland1/1(1)_001.jpg
If you follow the link to current mirror circuits you should have plenty to go on. In fact, a schematic published will be a condition of becoming the winner. This is supposed to be a challenge, after all.


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## dave-lvp (Mar 21, 2007)

allthatwhichis said:


> 8 bit DAC kit $33
> 10mW TTL Greeny=$80
> 20k scanners/galvos w/dmx board=360.00
> New link for popelscan download=Freeware
> ...



That is $360AUD, which works out to $290USD btw 

I should mention we are offering free shipping on these scanners if they are purchased via 'but it now' till mid april

Dave


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## allthatwhichis (Mar 21, 2007)

Thanks dave...


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## dave-lvp (Mar 21, 2007)

:rock:

Man, the smilies rock here


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## ambassador (Mar 21, 2007)

Regarding 



> If you follow the link to current mirror circuits you should have plenty to go on.


 
Relying upon references to generic "base" circuits is an unwise practice when the goal entails designing an extension to a specific manufacturer's circuit. Design factors involving impedance matching, transient response, resonant frequency, and other circuit characteristics are typically unique to a specific manufacturer's circuit. Thus, when a matter involves circuit design/alteration, it is the norm to begin with the actual "base" circuit (in the case of my request for the schematic, the actual "base" circuit's schematic). Designing from the actual "base" circuit's schematic in no way detracts from the contest principle. In fact, your generous offer of the actual laser pointers as a "base" from which to experimentally produce the additional switching circuitry enacts the exact same principle. 

If the actual circuit schematic is not available to you then; of course, you need not provide it. 

In either case, I am delighted that you have encouraged participation in this contest by generously offering the laser pointers to those who are pursuing the challenge. Thank you again abeland1! 

Ambassador 
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## dr_lava (Mar 21, 2007)

dave-lvp said:


> That is $360AUD, which works out to $290USD btw
> 
> I should mention we are offering free shipping on these scanners if they are purchased via 'but it now' till mid april
> 
> Dave




aww. I was actually going to bid on one.


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## dr_lava (Mar 21, 2007)

ambassador said:


> Relying upon references to generic "base" circuits is an unwise practice when the goal entails designing an extension to a specific manufacturer's circuit. Design factors involving impedance matching, transient response, resonant frequency, and other circuit characteristics are typically unique to a specific manufacturer's circuit. Thus, when a matter involves circuit design/alteration, it is the norm to begin with the actual "base" circuit (in the case of my request for the schematic, the actual "base" circuit's schematic). Designing from the actual "base" circuit's schematic in no way detracts from the contest principle. In fact, your generous offer of the actual laser pointers as a "base" from which to experimentally produce the additional switching circuitry enacts the exact same principle.
> 
> If the actual circuit schematic is not available to you then; of course, you need not provide it.




Although it would help, these driver circuits are simple enough that the schematic is reverse-engineerable by looking and probing at the circuit.
See the luckyduck thread I did a while back for an example.


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## abeland1 (Mar 21, 2007)

dr_lava said:


> Although it would help, these driver circuits are simple enough that the schematic is reverse-engineerable by looking and probing at the circuit.
> See the luckyduck thread I did a while back for an example.


Exactly


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## SenKat (Mar 21, 2007)

Abeland - I know I cannot compete with the big dogs - so I will stay on the porch and bark with the rest of us pups ! :naughty: 


I greatly look forward to the inventive genious that you have sparked with this competition ! In the infamous words of the UFC, " Let's get it on !"


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## ambassador (Mar 21, 2007)

Regarding: 



> these driver circuits are simple enough that the schematic is reverse-engineerable by looking and probing at the circuit.


 
That would; of course, require that one have the device in order to look at it and probe it. My request for the schematic alone was motivated by the desire to refrain from further taxing a generous offer of free R&D laser pointers. 

Ambassador 
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## dr_lava (Mar 22, 2007)

gotcha, well, I'll post it when I get it. I guarantee it's no current mirror like was posted, though. Too wasteful of power.


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## ambassador (Mar 22, 2007)

Thank you! 

Ambassador 
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## dr_lava (Apr 5, 2007)

Has anyone gotten their test lasers yet? I must say I haven't.


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## abeland1 (Apr 5, 2007)

dr_lava said:


> Has anyone gotten their test lasers yet? I must say I haven't.


Whoops, my fault, I relied on a verbal communication with Alvine to have your items sent. She is way to busy to pay attention to what comes out of my mouth. They are on the way now.

Who else is still waiting?


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## Aseras (Apr 5, 2007)

I got mine.. have yet to do much with them. it's grant crunch time.

I have torn 1 apart. very simple. gonna bea real pita to make it fit into the original pointer body. these guys are tiny. i though a leadlight was small.


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## Aseras (Apr 5, 2007)

ambassador said:


> Regarding:
> 
> 
> 
> ...



if i go ahead with doing a custom pcb, I'll send you the original one.

I'll post a HQ scan of the pcb now.


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## abeland1 (Apr 6, 2007)

Aseras said:


> I got mine.. have yet to do much with them. it's grant crunch time.
> 
> I have torn 1 apart. very simple. gonna bea real pita to make it fit into the original pointer body. these guys are tiny. i though a leadlight was small.


What will be very interesting will be how to get the pushbutton back in. LOL


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## abeland1 (Apr 6, 2007)

Aseras said:


> I got mine.. have yet to do much with them. it's grant crunch time.
> 
> I have torn 1 apart. very simple. gonna bea real pita to make it fit into the original pointer body. these guys are tiny. i though a leadlight was small.


What will be very interesting will be how to get the pushbutton back in. LOL


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## Aseras (Apr 6, 2007)

i was actually thinking i'd run a phono jack out where the pushbutton originally was and just wire it as always on.. at least that would make sense for a laser with ttl i guess.


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## dr_lava (Apr 6, 2007)

Aseras said:


> I'll post a HQ scan of the pcb now.




...


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## Aseras (Apr 6, 2007)

crap forgot to post that..












I already started to dismantle that one so R3 (the one on the back that is missing ) is a 104 100K ohm smd resistor

all the crud on everyhting is the crummy glue that holds it together... after you taker the pointer apart it'll never stay together anymore.. you push the button and the whole assembly pops apart and the head flys across the room


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## dr_lava (Apr 7, 2007)

Hmm from those pics, the circuit appears to be this:





but I'll know for sure when it shows up!


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## ambassador (Apr 8, 2007)

Thank you for posting the scanned images. 

Ambassador 
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