Topic: How to wire the ILDA connector?

[Things]

Heya's, i've got the sound card DAC and my DT25's. Now one thing I havent been able to get my head around, is the galvo's have a differential input, but  the sound card only has a single ended output.

How do you guys wire your DB25 connectors to the DAC? I have a Moncha DAC here that Dave has loaned to me, but as you can guess, it's not mine to keep, so i need to get my sound card DAC working. I connected DAC1 + output to + input on the galvo's, DAC1GND to the galvo ground, and not connect anything to the -. It works, but it makes it look like my scanner tuning is off, and I know it's not, because it works fine with Moncha.

Help please 

[Fanny Pack]

When connecting single ended outputs to differential inputs on scanner amps what you typically do is connect the + and - from the DAC to + and gnd on the scanner amp and then put a jumper across gnd and - on the scanner amp.  If you need to invert the signal you can connect to the + from the dac to - on the scanner amp.  - from the DAC still goes to gnd on the DAC.  You'd also change the jumper to +/gnd.

You'll be about 5v short when connecting single to differential so you'll have to either increase DAC output to +-10v or increase the Input Scale gain on the scanner amp.  If you don't do this then your image size will only be about 1/2 what it should be.

[Things]

Makes sense, thanks Gary 

Would anyone also be able to explain the weird output from the DAC? For example, with the Moncha device, the lasermedia test pattern looks pretty much perfect, but with the sound card, it looks like they need tuning. Any idea's?

-Dan 

[Fanny Pack]

I'll just be blunt and say that sound cards are a pain in the butt as far as DACs go.  I tried it and it took me a couple days worth of fooling around with the Windows settings to get the output right.  So, if your image looks funny you probably need to fiddle with some settings.  DrLava also posted some registry hack you can do to help, I think. 

[James]

Consider the fact that a lot of people come here to read about the use of a sound device as a laser DAC.

I wouldn't do it any other way, because that's my thing.

There is an art to it. You do need to learn about how it works.

But I can assure you, it works very well.

James.

[James]

Check it out:

The first one is for differential signals.

The second one is for single ended signals, including The LaserBoy Correction Amp.

When you connect the signals to the scanner inputs, if you only use two conductors from the db-25 (+signal & GND), make sure you ground the unused phase of the signal input pins.

[drlava]

Would anyone also be able to explain the weird output from the DAC? For example, with the Moncha device, the lasermedia test pattern looks pretty much perfect, but with the sound card, it looks like they need tuning. Any idea's?

'my car makes a funny noise, any ideas?'

you can't make a statement like that and not back it up with photos and more details to help us diagnose!

[BlinkenLights]

actually you can and he did but pics would help....

[Things]

I did try the idea of hooking DAC + to input + and DAC gnd to scanner ground, but didnt ground the - input. I'll try that and see if I get better results.

For some reason, I just updated the EzAudDac.dll and .ini in the Spaghetti drivers folder, but I can't seem to get my laser to output anymore. Hmmmm ...

[James]

The way it lays out on the connector itself makes it look a lot less confusing...... (I hope)


This is the top side of the board. The double row of pins is for the motherboard end of a parallel port ribbon. The other end has a DB-25-F.



This is the other side of the board. You can see that one entire row of pins (to the left) *EXCEPT PIN 17* are all grounded.

Pin 4 and pin 17 are aligned and this is your safety interlock switch (the red pair of wires).

On the other side of the double row of pins are the signals (the blue wires)

1 = X
2 = Y
3 = Z (not used)
4 = half of the safety interlock switch
5 = red
6 = green
7 = blue
8 = violet or any other signal usually associated with controlling the brightness of a laser
9 = another control signal
10 = another control signal
.
.
13 +5VDC shutter actuator voltage

Pin 13 is plain old USB voltage, right out of your computer, so do not expect to be able to draw any current from it!

James.  

[Things]

OK, here's my lasermedia test, same speed, same scan angle.

Sound card:


Moncha:

[James]

What software are you using with the sound card DAC?

James. 

[Things]

Spaghetti. So it could be that Spaghetti uses a weird version of the lasermedia pattern, but I dunno.

EDIT: I just tried making a .ild file with some simple text in it, and played it on Spaghetti thru Moncha, then the sound card, and the text looked the same on both, so I am guessing Spaghetti uses a different test pattern to the one I was comparing it to

[James]

Have you made any waves in LaserBoy?

James. 

[Things]

I would, but I have somehow managed to kill like 2 channels on my sound card, so I have moved my green laser to channel 5 on the correction amp output.