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

[DogP]

BTW, could someone try the music function on theirs? I decided to play around with it for a few minutes, bumping up the gain so it actually hears music, rather than just hearing when you hit the case. But it seems that it locks up after a few minutes... I tried turning the gain back down, but it's still the same. By locking up, I mean it stops responding to music, and won't even switch back to auto mode (you have to cycle power to get anything back).

Not that I really care about that functionality... just curious if that's another bug. I didn't really mess with it too much... it could be the frames I'm using or something too I guess.

DogP

[DogP]

I had some fun last night... I spent a couple hours drawing up the schematic for the galvo amp board. I'm gonna redraw it now that I know where everything goes, then I'll post it up tonight. Hopefully someone with more experience looking at galvo amp circuits can comment/annotate (Steve, I'm looking at you )... but overall it looks pretty simple.

DogP

[adventurevision]

Has anyone labelled all the internal pots for this projector? I've read through this thread and I don't think I've seen this mentioned? Just curious what they all do and since I'm still such a noob I don't want to go messing with them and screw anything up.

-Jeff

[DogP]

Has anyone labelled all the internal pots for this projector?

In post 181 and 195, tribble labeled the galvo amp board (minus the one unknown pot, which may be LIN?) and the galvo wiring. They're labeled consistent with the labels from this seller (since the boards are nearly identical): http://www.ebay.com/itm/15Kpps-laser...item45fd1ad76b . There's also a pot in the upper left corner of the controller PCB, which is the microphone sensitivity, and the three at the bottom are for adjusting laser power.

DogP

[adventurevision]

In post 181 and 195, tribble labeled the galvo amp board (minus the one unknown pot, which may be LIN?) and the galvo wiring. They're labeled consistent with the labels from this seller (since the boards are nearly identical): http://www.ebay.com/itm/15Kpps-laser...item45fd1ad76b . There's also a pot in the upper left corner of the controller PCB, which is the microphone sensitivity, and the three at the bottom are for adjusting laser power.

DogP

Geeze... thanks! Somehow I skipped all of page 8(posts 176-200). Great read! This thread is full of very useful info for noobs like me.

Thanks goes out to everyone posting here!

[tribble]

BTW, could someone try the music function on theirs?

I used it for a while... but I did notice as well that at one point it stopped responding. It was pretty cool while it was working, because I had created lines with dots, used the move_l2r frame effect to get a bunch of frames with dots in different positions, randomized the colors, and then randomized the frame order. When it was pulsing with the beat it looked pretty cool... until it stopped. Finding the right volume balance for a nice effect was really tricky. I suspect this is something better done with a more capable audio interface. I have an arduino and a 7-band graphic equalizer driver that is kind of fun because you can decide to modulate your visuals based on different portions of the spectrum. I have it hooked up to an RGB LED but I suspect it would be pretty simple to hook it up to the mic input of this critter.

[DogP]

When it was pulsing with the beat it looked pretty cool... until it stopped. Finding the right volume balance for a nice effect was really tricky. I suspect this is something better done with a more capable audio interface. I have an arduino and a 7-band graphic equalizer driver that is kind of fun because you can decide to modulate your visuals based on different portions of the spectrum. I have it hooked up to an RGB LED but I suspect it would be pretty simple to hook it up to the mic input of this critter.

Yep... external triggering is kinda why I was looking into it. But if it locks up, I'm guessing it's an MCU problem, not an audio trigger problem (since it won't even switch back to auto mode). :/ Probably some stupid error like needing to buffer from the SD, but stopping because there's no audio, and then never triggering on audio because it's still waiting on SD data.

DogP

[DogP]

Below is the schematic of the galvo amp board... I think it's correct, but it's certainly possible that I missed something, or made a mistake. Let me know if you think something doesn't look right... I can double check. I tried to make it neat, but I'm an engineer, not an artist... so that's what you get. For the most part, the cap values aren't labeled, since they're unmarked ceramics... if there are any critical cap values that you'd like to know, I can pull them and test... I just didn't feel like pulling out the SMD tweezers and de/resoldering all of them.

Also, I attached a couple pics... one is a picture of the board with labels (following the ebay auction's and tribble's labels... which is also how I labeled the schematics), with the LM324s removed from the X side. The other is a picture of the board backlit, so if you want to double-check anything, you can see most of the traces (there aren't many traces on the other side that aren't power and GND).



I don't know for sure, but I think that previously unconfirmed pot is LIN (so I've labeled that, though it can change if you disagree). The auction says: "LIN Zero offset (electrical offset of the driver, adjusted only in factory)", and looking at the schematic, it looks like it adjusts the offset between the two photodiodes. And although the layout is slightly different, I'm guessing it's electrically identical, so it seems unlikely that we'd have different controls.





To consolidate things, and for the future, when the ebay auction is gone... here's the list of pots:
IS Input scale (adjusted only in factory)
SG Servo gain (power of the feedback signal for internal PID controller
LFD Low frequency damping (correct overshoot)
HFD High frequency damping (correct undershoot) <---------not present on this board
LIN Zero offset (electrical offset of the driver, adjusted only in factory)
PS Position scale (increases or decrease input sensitivity of the computer, DO NOT change it)

So, if anyone would like to comment on the design, and especially suggest upgrades (maybe adjusting HFD?), I'd love to hear it.

DogP

[DogP]

I looked at the schematic more closely today... it definitely looks like a ripoff of the schematic Steve linked to earlier: http://www.skywise711.com/lasers/scanner/DSC_2073.gif . I can identify pretty much everything in the Spencer's amp from the Cambridge amp, except I think I made a minor error in the upper left section. I drew the 2K resistors tied together, both to the amp of Photo 1, instead of one to Photo 1 and one to Photo 2. I'll check it later tonight, but I'm pretty sure it's the other way.

There are also a couple pads for caps that are NOPOPs in the photodiode section that are present in the Cambridge one, and the HFD feedback loop is missing. It looks like by just adding one quad opamp and a few components, that I can add HFD to both X and Y. I might print a small board for that and try it out.

And the LIN pot matches R60 on the Cambridge, which is described in 7.1.5: http://www.skywise711.com/lasers/scanner/DSC_2051.gif .

DogP

[tribble]

Nice work, DogP! I wonder why I didn't see any changes when I messed with the LIN pot. It may have been something as simple as I was twiddling the wrong one, but I'm pretty sure I twiddled both. Ah, well, If I every get my scope probes replaced, maybe I will take a shot at re-aligning the amp with a 'scope.

Anyone know where I can get a a set of probes compatible with Tektronix 2245? The ones I have are TEK P6121, but I'd like something I could clip test leads to because I don't have four hands. Actually, I think the probes themselves may be OK; there is a resistor in the ground lead that plugs in to the probes; that is what fried. Ask me how... it involves a switching power supply and lack of an isolation transformer. Doh!