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

[james]

Try the modified sound card first.

[DogP]

BTW, as we've talked about earlier... I think there's definitely some room for improvement on the power supply end of things. I looked at the +/- 15V at the amp board, and both rails dip several volts (negative voltage is much worse). I upgraded the caps from 470uF to 1000uF (the largest that'd fit there), and there was a TINY, but noticeable improvement. It did reduce the dips a little bit, but there are deep long dips... I don't see fixing it with just caps. I wasn't sure if the load regulation was terrible on the power supply, or if the wires were undersized and having a large voltage drop on the way from the supply. So, I popped open the power supply, checked the voltage directly out of the switcher, and got the same poor performance. I added larger caps at the power supply with little improvement. With no load, the power supply output looks good, but the load regulation is worse than -10% over the range that this projector puts it through.

For fun, I decided to run the amp board off +/- 12V, since I could regulate that much better at the board. While overall performance suffered from the lower voltage (circle in the square was smaller), it was definitely a better image. Unfortunately, the switcher still dips below the dropout voltage of the 7812 and 7912 (what I had laying around), so even the +/- 12V isn't perfect (but way better). I figured the right thing is to just get a better power supply. I came across this: https://www.jameco.com/webapp/wcs/st...001_2100857_-1 , so I went ahead and ordered it (right price, too bad it's not enclosed... I'll probably just throw it in a Radio Shack project box). Specs say +/- 3% load regulation for both +/- 15V (with much better results in the test report). I'll post how it works out when I get it.

DogP

[mixedgas]

We usually put in 2-4 amps or more per rail per channel.
1A is kinda small for any large deflections/fast scanning.

Take a look at "Marlin P. Jones" or "Alltronics" or "All Electronics" for psu deals.

Steve

[DogP]

We usually put in 2-4 amps or more per rail per channel.
1A is kinda small for any large deflections/fast scanning.

Take a look at "Marlin P. Jones" or "Alltronics" or "All Electronics" for psu deals.

Steve

I looked for more powerful supplies at All Electronics and Alltronics, but all I found were these: http://www.allelectronics.com/make-a...-SUPPLY/1.html and http://www.alltronics.com/cgi-bin/it...utput-15VDC-2A . The first doesn't have a spec sheet, and I'd need two of them... and from past searches, the enclosed supplies seem to have worse specs than the open supplies (+/- 10% regulation is common)... don't know specifically on that one though. The Alltronics one has two 15V outputs... I wasn't sure whether that was 2x +15V outputs (common ground), or whether I could hook that up as +15V/-15V. It's more expensive, and no spec on load regulation either. I didn't check Marlin P. Jones, but I just looked, and don't see anything that's ideal.

I figured the original supply was +15V @ 1A / -15V @ 0.5A, and the 20K galvo set w/ two amp boards on ebay claims: "Input voltage requirements: +15V/1.0A，-15V/0.6A"... so hopefully a decent +/- 15V supply would be a worthwhile upgrade for this. I was also thinking of getting a +/- 18V supply, and using a 7815 and 7915 at the galvo board, but 18V isn't very common. A couple 20V laptop power packs might work though.

DogP

[tribble]

I figured the right thing is to just get a better power supply. I came across this: https://www.jameco.com/webapp/wcs/st...001_2100857_-1 , so I went ahead and ordered it (right price, too bad it's not enclosed... I'll probably just throw it in a Radio Shack project box). Specs say +/- 3% load regulation for both +/- 15V (with much better results in the test report). I'll post how it works out when I get it.

Recognizing that it's twice the cost, but did you consider two of the single-output 15V supplies? The 35-watters are 0.5% load regulation and the 65-watters are 2% (for the same price!).

I called another local spencer's, and they too are still at the $170 price point. Well, we'll see...

Steve, photodiode arrived today... shall I mail it up to you?

I have a long list of things to do with this projector! I want to try re-tuning at 8 degrees, but I think I will wait until DogP's power supply test results are in. I want to try tuning with the 'scope to get the linearity right, and I want to add that cap near the LED current source. All in time... work has begun again in earnest and I'm fighting off the crud that's going around. Get lots of sleep, guys... flu vaccine is only 62% effective this year, they say.

[DogP]

Recognizing that it's twice the cost, but did you consider two of the single-output 15V supplies?

Yep... I'm really trying to keep this as small as possible, and the dual output one is almost bigger than I'd like (I'd really prefer a quality wall wart)... but two single ones that are each about the size of the dual is really just too much for me. I'm certainly open to the idea though if this dual output doesn't cut it for me... but I figured I'd try for a simple good (cheap) solution that'll hopefully work, rather than jumping straight to an overkill solution.

FYI, here's what we're dealing with:

Original +15V (~1.4Vpp)


Original -15V (~2.0Vpp)


470uF replaced with 1000uF on +15V (~0.9Vpp)


470uF replaced with 1000uF on -15V (~1.3Vpp)


+12V linear regulator (cleaner, and only ~300mVpp)


-12V linear regulator (cleaner, and only ~500mVpp)


Also, there's a slight improvement to be had by connecting directly to the extra power header on the amp board, and powering the logic with the interconnect cable (rather than power->logic->amp). BUT!!! THE CONNECTOR IS PHYSICALLY THE SAME, BUT THE PINOUT IS DIFFERENT!!! YOU NEED TO SWAP +/- TO DO THIS. Doing this bumped both rails' peak-to-peak voltages down by ~0.1V at the amp board. Disconnecting the fan also helped a tiny bit.

The switcher IC in the stock wall wart is the FSDM0365RN... maybe I can mod it to output a higher voltage and just regulate it with a couple linears. :P

BTW, question about tuning... I always hear about tuning at 8 degrees, but is that because it's the standard, or is there something magic about it? Let's say I'm always gonna run the projector at 20 degrees... shouldn't I tune at 20 degrees, or should I still tune at 8?

DogP

[tribble]

FYI, here's what we're dealing with

Yeah, that's a bit uglier than the DMM revealed.

Are there higher-power DC-DC modules for +/- 15V that could be driven by, say, a 100W laptop supply? Then you could remote at least part of the power solution.

Disconnecting the fan also helped a tiny bit.

The fan was so noisy I disconnected it long ago. It doesn't seem to bother things for the relatively short durations I run it (less than the two hours stated in the manual, typically) and it's cold right now to boot. Maybe I will need it in the summer.

BTW, question about tuning... I always hear about tuning at 8 degrees, but is that because it's the standard, or is there something magic about it? Let's say I'm always gonna run the projector at 20 degrees... shouldn't I tune at 20 degrees, or should I still tune at 8?

I'm sure Steve or someone will give a better answer to that, but doing the 8 degree tests provides some data to more easily compare these scanners with others, since 'speed at 8 degrees' appears to be one popular metric, and it's the convention for the ILDA pattern. "Degrees at 30K" is another common metric, but I don't know that these things will ever hit 30K at a size large enough to tune to without walking to the other end of a warehouse.

[adventurevision]

I called another local spencer's, and they too are still at the $170 price point. Well, we'll see...

Ok, I went to the store that my wife returned our non-working projector to and they are not $129. I think the guy helping her saw the price for the R&B laser and thought it was for this one.

Sorry for getting anyone's hopes up.

[tribble]

DogP, what do you make of this critter? 2" square, 15V, 4A, 0.5%:

http://www.meanwell.com/search/ska60/default.htm

No idea on availability or price, though.

[DogP]

The fan was so noisy I disconnected it long ago. It doesn't seem to bother things for the relatively short durations I run it (less than the two hours stated in the manual, typically) and it's cold right now to boot. Maybe I will need it in the summer.

Yeah, they weren't messing around with heat on this thing. I couldn't believe the huge heatsinks for essentially laser pointers (since it's class IIIa, right? ), and that high speed noisy fan.

I'm sure Steve or someone will give a better answer to that, but doing the 8 degree tests provides some data to more easily compare these scanners with others, since 'speed at 8 degrees' appears to be one popular metric, and it's the convention for the ILDA pattern. "Degrees at 30K" is another common metric, but I don't know that these things will ever hit 30K at a size large enough to tune to without walking to the other end of a warehouse.

Yeah... that's what I mean. Is 8 degrees just so I can say "my scanner is better than your scanner", or is there something special there? Mine gets used at ~20 degrees, so I want it to look good there... but maybe tuning at 8 degrees will give me a good image at 20 degrees. I dunno.

DogP, what do you make of this critter? 2" square, 15V, 4A, 0.5%:

http://www.meanwell.com/search/ska60/default.htm

No idea on availability or price, though.

Those could work... but they're pretty expensive. Jameco sells the 40W (SKA40) for $43 each w/ a long lead time. And I don't think they're plug and play (I believe they still need large caps and adjustment resistors). And at 2"x2" each, I don't think they'll fit inside the case (ideally, I'd like everything enclosed in the case, or have a wall wart... I don't want exposed circuits, and I'd rather not have a homemade box looking thing). I guess a couple of these could work: https://www.jameco.com/webapp/wcs/st...001_1940521_-1 , or maybe a laptop supply and one of these (with caps and things inside): http://www.jameco.com/webapp/wcs/sto...001_1954130_-1 . It's only 1A per rail, but has good specs. I guess I should check what the actual peak instantaneous current draw is on these. I can't see spending a ton of money, just to get a little bit better power to this thing though (I imagine it'll help considerably, but not fix all it's problems).

On another note, I've drawn up my circuit for the sound card DAC. I'll probably just make it with through-hole parts, since it should still be small, and I don't have all the parts I want to use on hand in SMD (and don't feel like waiting)... hopefully I'll get around to putting it together this weekend. I also have the HFD board mostly drawn up... just need to print it out (maybe tonight). It's just one quad op amp, a few resistors, a few caps, and a couple pots.

And another note... I've drawn up the circuits for the laser drive and DAC->signal output. I'll post them when I get a chance.

DogP