Laser Projector (Red, Green, Purple) "Laser 3D Party Light" from Spencer's

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With all the screws tightened on the blue laser heatsink, it still moves around?

Well, I have one not-so-good screw on the bottom that connects the heatsink to the plastic base, so the heatsink tends to want to rotate w.r.t. the plastic base. I didn't tighten all of the screws on the plastic base all the way once I saw it was pretty well aligned. Then I put the back on the case and the wires pushed the heatsink forward enough to misalign it. I guess I will have to glue the heatsink to the base, then tighten the base with shims to get things close, and then go back and work with the tube. I don't recall there being much play between the heatsink and the diode mount; DTRs mount is a pretty good fit at 11.91mm.

I agree with Steve... I don't think the sag is that bad. If you're seeing it on your DMM, those caps probably wouldn't make much difference anyway (though it could fix higher frequency sags that you don't see). A better power supply would be nice, though probably not worth it IMO.

OK. Saves me $15 in caps. :-) I looked for better power supplies, but the ones I found were all in the $60-$80 range, which is ridiculous. I'd build my own linear before I spent that on a PS for this unit. :-)

Anyway, hopefully I'll get a chance to play around with this stuff again soon... just been busy lately.

Hope so; curious to see how your soundcard DAC project goes. I feel kinda bad 'cuz I've hijacked your thread a little... looking forward to seeing your machinations again. But, let me say again how thankful I am that this thread exists; after years of pining for a laser projector of any sort but not having the dough to buy one outright, this little puppy comes along and gives me something to cut my teeth on. :-)

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That sag at the psu is not so bad. Its the drop across the traces on the board that are lowering the led current. That is where you need your caps, just ahead of the led current source.

Given the input voltage sags described by the DMM, how big a cap do you think I need at the led current source? 1000uF? More? Less?

[DogP]

I looked for better power supplies, but the ones I found were all in the $60-$80 range, which is ridiculous. I'd build my own linear before I spent that on a PS for this unit. :-)

Yep... I'll bet this would run at +/-12V as well, so you could use a standard PC power supply, though you'd probably get less deflection and possibly poorer performance (and double the size of the system :-P ). With some component changes, you may be able to get better performance by going to +/-18V or +/-24V.

Hope so; curious to see how your soundcard DAC project goes. I feel kinda bad 'cuz I've hijacked your thread a little... looking forward to seeing your machinations again. But, let me say again how thankful I am that this thread exists; after years of pining for a laser projector of any sort but not having the dough to buy one outright, this little puppy comes along and gives me something to cut my teeth on. :-)

I'm glad people like you are in this thread... you're adding lots of good stuff, and sometimes I start a thread like this and I feel like I'm talking to myself. But yeah, I've also been wanting something like this for years, but couldn't justify the cost for an RGB system. This is great for what I'm looking for.

BTW, someone on the arcade forum pointed out that Spencer's has a 20% off coupon online with code "save20". I dunno how long it's good for, but at ~$140 shipped, I'm tempted to buy another!

DogP

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BTW, someone on the arcade forum pointed out that Spencer's has a 20% off coupon online with code "save20". I dunno how long it's good for, but at ~$140 shipped, I'm tempted to buy another!

I had a coupon in December too, but it wasn't good for items already on sale... but I successfully added it to an online cart and applied the coupon, so maybe it's good!

I think if I were going to spend $140 though I would buy a 'better' set of chinese galvos and see how much better they performed.

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OK, I think I've got this as good as I can get it. These are at Spencer Speed 20.

ILDA12K:


LaserMedia:


Quadrature:


The Quadrature shows the overshoot and undershoot, but the other two tests look better with these settings.

And here's a hypcycloid I generated with LaserBoy. The centers are much rounder now, though I don't think I posted a 'before' pic here:


That's it. I'm done tuning. :-)

I spent an hour re-aligning the blue this morning... until it was perfect at 30'... tightened everything down good and snug. Two hours later, it had drifted off again. &%^&%%$#! Next time, glue. :-)

[mixedgas]

Put 100 uF to 1000 uF near each led By this I mean find the LED's current limiting resistor. Put the cap's + lead on the hot side of the resistor and the other end to the ground where the ground lead comes in from the galvo. Dont put the larger cap across the led itself.

You could then put a .1 uf ceramic from Radio Shack across the led itself, lead to lead. I would not place anything larger directly across the led.

The Laser Media pattern looks much better now that you dont have the fiber stuck in the position sensor.

You tuned at 8 degress of angle, right?

Steve

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Put 100 uF to 1000 uF near each led

I'll try that next time I have it open... what effect will I be looking for as improvement?

You tuned at 8 degress of angle, right?

If I read the pangolin scan angles table correctly, it was more like 16 degrees. 85" throw for 24" image. That was just the table space I had clean near a wall. :-)

I tested the scanner speed via the low-fi way; with an .ild with 250,000 points and a stopwatch. Mine turns out to be about 15Kpps at Spencer Speed 20. So, does that mean the test images are about 15Kpps at 16 degrees?

[DogP]

OK, I think I've got this as good as I can get it. These are at Spencer Speed 20.

Those look pretty good for speed 20... nice job!

I spent an hour re-aligning the blue this morning... until it was perfect at 30'... tightened everything down good and snug. Two hours later, it had drifted off again. &%^&%%$#! Next time, glue. :-)

Did you put the back on? I found that when reassembling, you need to be careful of the wire routing, or the wires will press against the blue heatsink (since it's the farthest back) and cause just enough force to push it a little bit out of alignment.

I tested the scanner speed via the low-fi way; with an .ild with 250,000 points and a stopwatch. Mine turns out to be about 15Kpps at Spencer Speed 20. So, does that mean the test images are about 15Kpps at 16 degrees?

The problem with the stopwatch method is that there are small gaps throughout the animation, probably where the MCU is buffering from the SD card. So, most likely you're slewing faster than 15Kpps, but pausing for split seconds here and there, for an average of 15Kpps (that's what I noticed from looking at the DAC output on the scope).

DogP

[james]

I'm interested to see how much you can improve the image quality using the modified sound card DAC and tweaking the LaserBoy optimization settings.

James.

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So, after poking at this thing for quite a while, I think there is a bug in the show card's interpretation of the ILDA format 0 data.

James will attest that I'd been trying to get to the bottom of why my laserboy-generated figures were missing vectors, sometimes quite a few. I suspected an off-by-one error somewhere in the chain, and I think it's in the Spencer projector showcard.

The bug is this: The color and blanking status of a vector is taken from a LATER vector instead of the vector it belongs to. This means lines change color before they should, or blank before they should, and in general make messes of some portions of some graphics. In some graphics, the effect is not noticeable, I think because it occurs within a dwell time period.

Here is one example that comes from a frameset that ships with the projector and is otherwise available on the 'net, abst-new.ild. This is frame 498 as rendered in LaserBoy, but zILDA shows the same coloration:


The 'walls' of the tunnel are cyan (blue+ green) up until the green ring, and then green outside of it.

Now look at how this image is rendered by my copy of the Spencer projector:


If you consider the order of the vertices as described by laserboy, the cyan line stops 'early.' This line is drawn from top-right to bottom-left of the image. I verified that the Spencer projector draws the points in the same order by creating a very large circle and scanning it very slowly to see which way the circle was drawn. The projector does draw the points in ascending order as indicated by laserboy.

I have other samples as well; some are posted over at the LB forum, some are just lying around on my camera. In my mind, there's no question that the showcard is prematurely adjusting the lasers when reading vertex information and sending it to the DAC. I haven't determined if it's a fixed offet error than can be corrected simply by shifting all of the color information one vertex forward in the ILDA file or if it's more a complicated timing issue that will vary based on the scan speed.

I have noticed that the magnitude of the error is larger for higher scan speeds, but I think this is just due to the fact that at high scan speeds the scanners are just more physically 'behind' the current command than at low scan speeds. I have to say at scan speeds of 5 and below, you can really see the 8-bit-ness of the DAC come through in the art.

Anyhow, I just wanted to get the group's opinion on what they have seen and how easy they think this may be to correct with a "SpencerProjector" filter we could pass ILD files through.

Best,
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