Advice on a chinese POS

[LEDpaint]

Hi Everyone,

First off, I want to introduce myself. I do lighting in NJ, been doing it since around '97. Saw a Mobolazer Lil G in a shop, salivated, and bought it, which kept me eating beans and ramen for months. Upgraded the thing to 35mw (never measured, but it looks brighter; I'm guessing I'm overdriving it a bit or it's simply putting out more power than it's rated for, mfg unknown) around 2001, and it's pretty much sat and collected dust for years after. Pulled it out about a year ago and hung it in my bedroom after watching the Sensation dvd's and seeing the kick-ass lasers they used. The laser bug bit me hard, so now I find myself really drooling for an RGB after lurking for months on this forum.

So, cutting to the meat and potatoes of my post, my plan is buy a chinese POS RGB for about $600-800 to familiarize myself with the internals and operation before buying myself the parts to build a premium projector.

So, my question is, for the money, which sucks the least? I found this on ebay, but any advice is appreciated:
http://cgi.ebay.com/500mW-RGB-violet...item45efec37a7

[Doc]

Hi Everyone,

First off, I want to introduce myself. I do lighting in NJ, been doing it since around '97. Saw a Mobolazer Lil G in a shop, salivated, and bought it, which kept me eating beans and ramen for months. Upgraded the thing to 35mw (never measured, but it looks brighter; I'm guessing I'm overdriving it a bit) around 2001, and it's pretty much sat and collected dust for years after. Pulled it out about a year ago and hung it in my bedroom after watching the Sensation dvd's and seeing the kick-ass lasers they used. The laser bug bit me hard, so now I find myself really drooling for an RGB after lurking for months on this forum.

So, cutting to the meat and potatoes of my post, my plan is buy a chinese POS RGB for about $600-800 to familiarize myself with the internals and operation before buying myself the parts to build a premium projector.

So, my question is, for the money, which sucks the least? I found this on ebay, but any advice is appreciated:
http://cgi.ebay.com/500mW-RGB-violet...item45efec37a7

It may be tempting, but you will end up going DIY and junking the POS, effectively flushing the $800 down poop shute. So spend your money on a case, a set of budget but useable scanners and a budget quality green laser (think Laserwave).

The inexpensive green Laserwave will without doubt be outputting more than it says on the label, it will have analogue modulation and it will have a warranty that you probably won't have to use, but will be honoured if you do. Speak to Marc (gottaluvlasers) on this site for your hardware requirements.

Build a sound card DAC, download one of the free or cheap useable software packages and you're good to go and much happier.

So long as you buy a case with some room in it you can add colours as the funds allow, and there will be endless help right here to help you build.

You should be able to do all of this for $800 and will have a projector that will blow the RGB POS right out of the water, plus you will have made it yourself.

Ian

[LEDpaint]

I did think the same a few minutes after I posted and this was the answer I was expecting as my first reply.

I happen to live within driving distance of Marc and have spoken to him on the phone. Part of my plan was to use the case from the POS and ditch the internals or just recycle them for for a set up in the garage, becaue DIY ultimately is the way I want to go, anyway. The memories of beans and ramen haunt me, however, but I guess I have to do what I have to do. As long as I repeat "prime rib" to myself, maybe it won't be so bad...

Some advice I have received from working laserists is go at least a watt, but I see a lot of guys here working with less than a watt combined power. Is that really going to limit me as to the types of shows I can do as everything I do is warehouses and relatively dimly lit nightclubsof about 1500-3000 sqft? Is working at 1/2 watt RGB a decent way to go until the rig earns me enough to bump to a watt? I can always keep the 1/2 watt heads for a new projector or sell them later. Is their advice sort of like the Porsche purists telling me stick with Porsche when my budget is Nissan 350z (certainly no supercar, but still plenty sporty for most people). I'd like to maintain a nice white balance, but could probably afford to put a more powerful green and red in and simply dial them down to more properly balance with the blue. Although perfect balance is nice, does that even matter considering my audience isn't likely to be picky with an aerial show?

It may be tempting, but you will end up going DIY and junking the POS, effectively flushing the $800 down poop shute. So spend your money on a case, a set of budget but useable scanners and a budget quality green laser (think Laserwave).

The inexpensive green Laserwave will without doubt be outputting more than it says on the label, it will have analogue modulation and it will have a warranty that you probably won't have to use, but will be honoured if you do. Speak to Marc (gottaluvlasers) on this site for your hardware requirements.

Build a sound card DAC, download one of the free or cheap useable software packages and you're good to go and much happier.

So long as you buy a case with some room in it you can add colours as the funds allow, and there will be endless help right here to help you build.

You should be able to do all of this for $800 and will have a projector that will blow the RGB POS right out of the water, plus you will have made it yourself.

Ian

[Doc]

If you start with 250mW of green you have the first building block for a 1.2W RGB

250mW green + 600mW 640nm red + 400mW 473nm blue,= 1.25W of nice white.

Note: the figures above are the theoretical best match, but the human eye is very adaptable and a good apparent white can be made with less blue, less red, more red etc.

But of course by building it yourself you have the option of first adding the red and having a very nice RGY. Then when funds allow, add the blue.

And don't forget; we are talking actual real life James Watt Watts, not ebay P.O.S. Watts (which seem to differ somewhat)

[LEDpaint]

My wallet protests, but you've convinced me.

Thanks for the advice!

[Dr Laser]

The first question for RGB is now much blue can you afford!

For 400mw 473 you're looking @ 3200$
But you can get away with over specing 300mw which is about 2200$

I would recommend not to waist your time with low power if you planing to continue. Get as much green as you can afford. Green is the cheapest and you can always tune it down. 400mw is about 700$ now. and 500$ is 900$. Start with this. 400-500mw is a very good power for semi-mid indoor. Then you save more money and get 800mw 642nm. Then save some much more and get 500mw @ 457nm which is about 3K. The reason is that you will never have to trow old lasers away.

If you still want to start low. There is this http://www.photonlexicon.com/forums/...ojector-399.00

[buffo]

Greetings, LEDpaint! Welcome to PhotonLexicon. From your background, you sound like you'll fit in just fine with the rest of us laser freaks!

I happen to live within driving distance of Marc and have spoken to him on the phone.

Then you are fortunate, indeed. Marc is a highly respected member of the forums, and an accomplished laserist. He can offer you all sorts of advice (and assistance). He's also a great guy! Get together with him over a beer or two and a good steak dinner when you get the chance.

everything I do is warehouses and relatively dimly lit nightclubsof about 1500-3000 sqft... Is working at 1/2 watt RGB a decent way to go until the rig earns me enough to bump to a watt?

This depends on the type of show you're trying to do. if you want to to graphics shows, then a half watt RGB projector is perfect. But if you're talking about doing a beam show, then a half watt is going to be a little on the low side. You *might* be OK in a 1500 square foot club with dim lighting and a good fog machine (or better yet, a hazer), but you're going to have to make sure you use a bright red (either 642 nm red or 635 nm red). Those e-bay units usually use 650 nm or 660 nm reds, which won't be bright enough in a 500 mw projector.

Truthfully though, if I were planning to do commercial shows, I'd try to bump up to a slightly more powerful projector. A 1 watt RGB rig is definitely the sweet spot, but maybe you can compromise and go with something in the 700-800 mw range.

As far as buying one of the cheap projectors on e-bay, I would not recommend that. As Doc already mentioned, that money will be essentially wasted. Better to spend it on a better controller than on a cheap projector that you're going to have trouble with in the future. (And which will not be bright enough to use for a commercial show anyway.)

Is their advice sort of like the Porsche purists telling me stick with Porsche when my budget is Nissan 350z (certainly no supercar, but still plenty sporty for most people).?

No, not at all. Sticking with the car analogy - it's like this: You just bought a new boat, and you're trying to decide if you should buy a pick-up truck to haul it, or if you should just put a bumper hitch on your old Ford Taurus and tow it that way. Your friends that are telling you to buy the truck (the 1 watt RGB) are concerned that your 4 cylinder Taurus (the 500 mw rgb) might not have enough grunt to haul the boat up the boat ramp.

Now, if someone was telling you to go purchase a 4WD Cadillac Escalade (3-5 watt RGB) to haul your boat, you might start to question their advice. But there's no doubt that the pick-up truck is far more preferable to the Taurus with a bumper hitch.

Although perfect balance is nice, does that even matter considering my audience isn't likely to be picky with an aerial show?

Yeah, adding extra green is one way you can cheat... You buy the most expensive blue that you can afford, try to add enough red to balance it fairly close, and then you add extra green to get more total power. Sure, your color balance isn't perfect, but as you said, the audience will never know.

I've seen projectors with 200 mw of blue, 500 mw of red (at 635 nm), and a full WATT of green, and it still looked impressive. Now, I'm not recommending you go that far, but you could certainly try 200 mw blue, 500 mw red, and 300 mw green... That would give you a full watt of output power, and even if you balanced everything, you'd still be in the 750 mw range. (And if you can't swing that, then drop down to 150 mw of blue and 400 mw of red and you're still in the ballpark.)

Ask Marc to show you some pictures of some of the projectors he's built for other people. Then look at the power levels of the lasers, and you'll see that often times what "looks good", "is good". You can play around with Tocket's Chroma software to get something that is close, but don't be afraid to add an extra hundred mw or two of green, just to get some extra punch for your beams.

Adam

[LEDpaint]

That's a great idea, and turning the power down on higher power reds & greens to match a lower power blue until I can afford a higher blue did cross my mind as well. (I'd like to go full rgb off the bat, if I can).

as a rule of thumb, how far can I push a 300mw (or any power laser, for that matter) before I'm significantly hurting the life of the laser? Is upping the amperage(?) about 10% going to get me 10% more wattage, and what effect will this have on the life of the laser? I'd rather be cautious and save for better in the future than blow this thing doing something it isn't designed to do.

The first question for RGB is now much blue can you afford!

For 400mw 473 you're looking @ 3200$
But you can get away with over specing 300mw which is about 2200$

I would recommend not to waist your time with low power if you planing to continue. Get as much green as you can afford. Green is the cheapest and you can always tune it down. 400mw is about 700$ now. and 500$ is 900$. Start with this. 400-500mw is a very good power for semi-mid indoor. Then you save more money and get 800mw 642nm. Then save some much more and get 500mw @ 457nm which is about 3K. The reason is that you will never have to trow old lasers away.

If you still want to start low. There is this http://www.photonlexicon.com/forums/...ojector-399.00

[buffo]

as a rule of thumb, how far can I push a 300mw (or any power laser, for that matter) before I'm significantly hurting the life of the laser?

With a DPSS blue, I wouldn't try it. If you blow the pump diode, you'll have to re-align the cavity after you replace it. This is not an easy task, and you will probably end up with less total power after the work is complete. Even a DPSS green is tricky to align after swapping the pump diode... More to the point, most commercial drivers do not easily allow you to adjust the drive current.

However, there are a few manufacturers (LaserWave is one) who will sell you a 300 mw blue that will actually be making closer to 350 mw right out of the box. So you can cheat a bit if you go that route, and be safe in the knowledge that you're not over-driving anything. (They simply de-rate the laser up front, knowing that eventually the output will drop off slightly after a few thousand hours of operation. So you get some extra grunt up front for free! )

Is upping the amperage(?) about 10% going to get me 10% more wattage, and what effect will this have on the life of the laser?

As a general rule, more current = more output. However, the relationship between drive current and laser output is not always linear, even for a simple red diode (which is a direct injection laser). When you start talking about a DPSS design (where you have a pump diode, a lasing cavity, and a frequency doubling crystal), you can throw linearity out the window. There are just too many variables to predict exactly what the output power will be.

Often you will hit a "sweet spot" in the lasing medium or the doubling stage that will drastically increase efficiency. Then too, it's possible to saturate either the lasing medium or the KTP, in which case extra pump does not mean more output power. This is one reason why the modulation response curves for DPSS lasers are notoriously non-linear.

Typically, you'd rather over-spec the diode and run it below it's maximum current. However, some folks have built their own red modules using cheap long open-can red diodes, and they've had very good luck driving those diodes right to their theoretical current limit so long as they're protected against static (with Lasorbs) and excessive heat (with a large peltier cooler). But this is not recommended for a DPSS design, because of the problems involved in re-aligning everything if the pump diode blows.

In short, it's probably not something you'll want to attempt with the projector you're thinking about building.

I'd rather be cautious and save for better in the future than blow this thing doing something it isn't designed to do.

Smart thinking. I completely agree.

Adam

[Weiland]

Hey there LEDpaint, nice to see another noob on here that was in the same boat i was in. I just recently bought one of those 1/2 watt RGBv EBAY lasers from the ''Chinese Garden''.......and a fiasco it was.

They first sent me an RGY that only the green modual worked in. Then they argued with me for a week that they sent the right one. I finally had to file a ''CASE' to ebay about them and send in a video of what the laser actually did. so ~FIRST OFF be CAREFUL on who you are dealing with on ebay~ ! ! ! !

The one good thing out of it all was they let me keep the first laser projector and sent me a second one (that was an 1/2 watt RGBv like i paid for in the first place) at no extra charge....

Second thing is being new to the construction of a laser projector, i wanted something that was already built that was not to expensive and that i could possibly rebuild with the existing parts.

It always easier to learn something if you have it in front of you to look at. This has been a big help for me in actually seeing how it all fits together and taking it apart.

There are some down falls that i have seen so far with them.

1-being that he glavos are not what they advertise ....more like 5k -10 k instead of the 20,000-30,000
2 -the dichros are usualy GLUED in place permanently and are not adjustable.
3- no safty keys for nonusers messing with them.
4 -there is no ILDA out on them..only an in .so if you want o hook up another laser you will need a splitter or another software usb interface.
5- no connection for a Quick safety shut off.
6- glavos could be out of whack....the first one they sent , the animation was all sorts of crazy and misshaped .


BUT ! the on the lighter side of it all ... to ME it was a good first start to learn and to play with. if you look on my personal profile page there are some pics of the laser's beams. I have played with it in the back yard and its not to bad at all. you do have to have a smoke machine or a hazer to see the beams tho. The animation is fine and very clear.


once i get the software for mine, i am sure ill be able to pull more colors and definition out of the laser.

This is the company that most of the EBAY Chinese lasers are being bought from and resold.
http://www.szshinp.com/en/show.asp?xid=51

Here is a pic of the gutz of mine. one of the things i liked about this is that they enclosed the RGBv moduals in another box to protect them from dust. Dont know if they will do that with that one you are looking at.

I hope this helps you a bit in your decision. Good luck