im not sure...probably the lasers messing with the cmos sensor inside the camera.
Senior Member
im not sure...probably the lasers messing with the cmos sensor inside the camera.
Senior Member
Yeah I know... CMOS or CCD.. doesn't matter... it's dead pixels all around now!
Senior Member
if anyone can make more sense of what is being displayed in the video,id appreciate it...i cant tell if hes measuring a single diode or the entire array..and dont know what in the world the 0.859 reading would be attributed judging from his lead positions i dont think hes doing current (the red lead would be on the far left ports for current wouldn't it?) and i think (but im not sure) that the LCD is showing neg polarity.
Senior Member
he's measuring voltage, so it just doesn't matter.... the voltage should stay the same for an LD, the current must be modulated....
Senior Member
someone said on youtube something about 600mw..here is a cut and paste
lol, it did not burn the ceiling i think because it was white. and it powers it at 600mw to increase the lifespan of the laser diodes. the laser array is already focused like that, they cross because i put a magnifying lens over it.
iminyourbasement 2 days ago
i think the guy meant to say 600 millivolt cause i dont see where miliwat factor in..ok so each laser is getting less than a volt but something of a high current (say barely a few hundred miliamps around 250 or so?)..and to decrease or increase brightness that current is being modulated?....or pulsed?
when i do the math of 32v per string divded by 6 diodes in each string i get
32 divided by 6 =5.3.....and the other way around 6 divided by 32v =0.1875v.......now something is telling me we have to factor in the forward voltage drop into this number correct?....anyone know what that may be?
and when i do the math for the current....using the safe assumption that each string gets 1.5amps
1.5a divided by 6 equals 0.25a (or 250miliamps) 1/4 amp?.....and the other way around 6 divided by 1.5=4 (ok now im official lost)....again does the forward voltage drop affect current?..is that why my numbers are off from whats in the video?
these projectors...are starting to suck!
Senior Member
Check the datasheet for the diode you will find how may amps it can handle and the forward voltage!
Senior Member
does anyone happen to have the data sheet?...me and a freind of mine have been scouring the net and cant find hide nor hair of it...closest thing we got to was this.
http://www.nichia.co.jp/specificatio.../NDB7875-E.pdf
it seems any and all documentation to this projector or its internal parts is strictly controlled and not readily available.
Member
I just stumbled on this thread. I didn't know other people were working on this too. Very cool.Originally Posted by LesioQ
Just a hot update:
20W 445nm LED: 3.3W@445nm, 1A@11V, effeciency=30%
collimation: PITA ...
Piotr.K
Attachment 26060Attachment 26061
I've successfully been able to replace the LDs with an array of 4 high powered LED plates, on the heatsink, and run them from the KasEO cable.
The challenge? Collimation. The LED plates on their own do NOTHING to produce Blue/Green without optics, and even a very short focal length glass lens on each emitter plate is not enough.
Last edited by rhd; 10-17-2011 at 04:50.
Senior Member
dude you are my new best freind!!..do you have any pictures?..how large were the led plats and what voltage,current,lumens output?...did you use white leds or colored blue leds?..also did you dummy resistor any spares out? and last queston...did you happen to get the red led to turn on?
any and all info is appreciated.
finally someone whos got some results!!
Keith.
pc sorry for the deluge of questions..i just got excited
Member
I used 13V Blue (there's no reason that I can think of to go with white) LED plates, designed for ~800mA current. One on each channel, plus basic diodes to drop the remaining voltage into the range that the projector expected to see.
Yes to the RED. I've been able to run the projectors on just the RED channel successfully, get an output image, browse through the built-in menus based on the RED output, etc.
I used a KasEO cable that was entirely intact (including the two side temperature sensors), so I didn't need to deal with bypassing overheating circuitry. That said, I'm certain that the side thermistors could be replaced with a 10k resistor in situations where the ribbon is trimmed and loses those two in the process.
I fabbed a PCB to take care of the excess voltage dropping (photo attached) and the connection points:
It's sort of a "catch all" for tinkering with this project. It has the connection points to use one big resistor to bypass a channel entirely (as discussed earlier in this thread / the OP). Or you can bridge the resistor connection point, and instead run the channel through a circuit of 6 diodes + the LED emitter. 6 diodes with a high voltage drop (of around 1.5V) plus the LED emitter is generally in the right range to trick the projector into thinking it still has its LDs attached.
There are also solder pads for adding the two side 10k resistors.
I'm somewhat unclear on what the components (more thermistors?) that parallel each diode channel are. I included a spot for them on my PCB, but I'm not entirely sure I understand whether those are just additional 10k thermistors, or are something else. It seems odd to me that they could be used as thermistors to monitor heat, when they're literally parallel with a diode channel (or at least appear to be from the ribbon cable). However, those solder pads are there.
For connection to the actual projector, I have been taking the approach of just stripping a bit of the solder resist / plastic coating off the top of the cable, and soldering a short flexible wire between my PCB solder points, and the KasEO cable.
But yes, anyway, getting the projector to run without error, and even project a purely RED image, is no problem. The sole remaining hurdle at this stage, is figuring out how to collimate the blue light enough that it actually projects. That said, it's actually pretty fun just to have a working RED-only projector. At least better than throwing them away
Last edited by rhd; 10-17-2011 at 12:34.
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