Ilda dac help please...

[cliveharper]

Hi Everyone
I have this DMX display board but i want to link a DB25 cable to it so i can use laser display software as my old projector does not have a ILDA input, is it possible to connect a cable to this board so i can turn it into a ILDA type..?
Sorry the picture is a little blurry...


Please can anyone help me...
Thank you
Clive

[KGB]

this picture sucks.... if you want help you need to take a picture where we can actually see the board. ...and what kind of scanners does this use?

[cliveharper]

My camera is abit rubbish... Ok, the white plugs from left to right are :- (-15/G/+15) (-15Y/G/X+15) (MIC)(VR) (+5B-/A+/G/+15) and the right side from top to bottom are (G Revs) (GB)(GG)(GR).. The white plug under the main IC is for DIP switches... The scanner kit is a 15k twin board...
I cant get the picture any better because of my rubbish camera...

[colouredmirrorball]

I think it's a Spacelas board. It only generates signals for the several projector components controlled by DMX, it does not accept ILDA input. You need to connect it to the components directly, or somehow connect them to the wires of a ILDA cable, and plug that into the projector. Just using a "sugar" (what's the English name again?) would work
(http://www.tibo-elektro.be/Images/OB...78/3955117.jpg).

Or do you want to send ILDA signals from the DAC to the Spacelas board? That is not possible. You need a breakout board for that, but they're not that expensive. I think DZ, Stanwax and Dave sell those.

[cliveharper]

The sort of DAC i would like is something i can plug the scanner and laser into like the DMX board but with a db25 input..
I know of the soundcard DAC which i am building but i would like to find a schematic where i can build a DAC to put into my projector and scrap this DMX board but the only schematic i have found is a blida but that has no input plugs for the parts.. I have spoken to Rob from Stanwax and he said that what he has is not what i need sadly..
I didnt think finding a DAC system would turn out to be so difficult..

[colouredmirrorball]

Well a soundcard DAC has several outputs: R, G, B, X, Y and maybe some others. That is the "ILDA" output. Each component in your projector has an input. So just connect the output from the soundcard to the inputs from the components. This means you need to put the soundcard inside your projector, and this can cause problems with cable length. If you want the option to have longer cables, you must attach the outputs from the soundcard to a ILDA cable (by the "sugar" mentioned above for example), and use a breakout board inside your projector: (Stanwax' board). This board gets input from an ILDA cable and provides easy output for the several components. This isn't necessary but it makes things easier. You could just attach the ILDA cable to another "sugar" and get done with it, it works as well.

[cliveharper]

I will do that, thank you ..
Ive built a bigger wooden box for the parts to go into ready for when i have everything i need to turn this basic projector into a unit i can use software with... I cant wait to show it off once its up and running..

[james]

If you are starting out with the basic elements of a laser projector, like a pair of scanner amps and scanners and the lasers themselves with their own modulation inputs (either TTL or analog) and you want to tie all of these inputs together into a DB25 connector, you should make sure you pay attention to they way you deal with the negative side of differential signals and the common ground.

It is very likely that your scanner amps have differential inputs. That is, there are three pins; a positive signal in, a ground and a negative signal in, for both X and Y. It is probably best to take all three pins of each amp input to the appropriate places on the DB25. In the ILDA spec there are designated pins for +X, -X, +Y, -Y and system ground.

If you make a modified sound card, aka LaserBoy DAC, it will be single ended. There will be no negative signals, only positive signals and one-and-only-one common ground. The pins on the DB25 that correspond to -X and -Y will simply be the common system ground. That's fine. It will work. As soon as you connect the LaserBoy DAC's DB25 to your projector's DB25, you will ground the negative inputs to your scanner amps.

The point is that you can use some other laser DAC that might be truly differential and you will not have to worry about shorting out the negative signal lines from that DAC.

James.

[colouredmirrorball]

It is very likely that your scanner amps have differential inputs. That is, there are three pins; a positive signal in, a ground and a negative signal in, for both X and Y. It is probably best to take all three pins of each amp input to the appropriate places on the DB25. In the ILDA spec there are designated pins for +X, -X, +Y, -Y and system ground.

No. The Spacelas board (if that is what it is) has a plug labeled 'X G Y' which suggests single ended scanner amps. Also I think it is common for 15k scanners to be single ended. So there isn't really an issue. Good that you thought of it though, but fortunately there isn't a problem.

So just connect the X and Y outputs from the DAC to the X/Y input on the scan amp, and G to the common ground (that is also used by the laser modules).

[james]

Well, in general, this is something to be aware of when wiring the individual parts of a laser projector into a DB25.