USB Audio DAC mod + LaserBoy Correction Amp

[seanharrison]

first off what is the scan angle?

in spaghetti you can set it at an exact angle but in the box on the top left of the more menu there is a box you can adjust size. adjust that down to a smaller size

I have the red box set to about 5-10% in size.

From the first photo it looks like you'll be able to get at least 20k ilda tuned in well. make sure optimization is off in spaghetti as you tune.

I have been trying it tune it at 20k for hours and that is the best image i can get from it

In LaserBoy, there are settings in the [Tab] menu that get used when the vector art gets optimized and written to wave.

If you decrease the value of setting '3' longest optimized vector in points, you will be asking your scanners to move a shorter distance between clock samples.

You can also increase the dwell time, setting '4' maximum dwell in microseconds. The idea here is that the sharpest angle you can expect your scanners to draw is 180 degrees, in other words, while moving in one direction, they stop and go completely backwards. Angles less than 180 will get less dwell time. Dwell time comes down to a number of points (samples) sitting on the same spot in a corner of your drawing.

Another thing you can try is to change the sample rate of the wave. Although I do not recommend this approach. Your sound card DAC really only does 48KHz, no matter what you stream to it. The driver will resample everything to clock out at 48KHz. However, if you chose sample rates that are integer divisions of 48000, you should get decent results. That is to say, if you choose a sample rate of 16000, then each point will be clocked out three times in a row at 48KHz. That should be fine.

If you decrease the longest optimized vector in points and / or increase the maximum dwell in microseconds, you will be adding more points to each optimized frame, so each frame will take longer to render on your scanners and it will flicker more.

Obviously, after you make these settings changes you will have to regenerate you waves.

James.

I will give it a go, Is this a limitation of my Scanners or something that just needs to be done normally?

[James Lehman]

I don't know about your scanners. These settings are just there to help you get better results from whatever you have.

LaserGuy216 had some issues when he first started working with the sound card and LaserBoy. He got them worked out though.

I wonder if he might chime in here and tell us what he discovered.

James.

[buffo]

Sean;

Your tuning is off, but you may have difficulty tuning your scanners until you're *sure* you have your sound card dialed in correctly.

I have a sound card DAC with a correction amp that I saw working perfectly at SELEM 2008. However, when I connected it to a different computer, all the gain settings on the correction amp were wrong and I had to re-adjust them. If I had tried to tune a set of scanners with the amp in that condition, I never would have been able to get them dialed in right.

First, forget about the ILDA2 pattern. The main ILDA pattern is the one you need. Second, a pic of the LaserMedia test pattern would help. However, from the pictures you posted, it looks like you've got some overshoot (evident on the quadrature square wave picture). You also appear to have some timing issues with your blanking signal (thus the tails you see).

Do you have another controller you can tune with? Or, barring that, do you have another set of scanners that are already tuned so you can check the settings on your sound card dac?

Those scanpro 20's can be dialed in to give you a perfect ILDA pattern at 20K (Don't try to run them at 30K though - they're not designed for it and will only give you fits, even at small scan angles.)

See this picture for details: (The bowed side is not an artifact of the scanners. The sheet I was projecting onto when I took the picture was moving from the wind of the ceiling fan.)

Adam

[Things]

wow, was that done with the scanpro 20's?? I am having a **VERY** hard time tuning mine, they are never perfect. Once i get a new galvo PSU from dave (I somehow let the smoke out of the original one ) I may try readjusting my sound card. Mind explaining how the sound card can screw up the tuning? Something to do with the output voltages?

[seanharrison]

wow, was that done with the scanpro 20's?? I am having a **VERY** hard time tuning mine, they are never perfect. Once i get a new galvo PSU from dave (I somehow let the smoke out of the original one ) I may try readjusting my sound card. Mind explaining how the sound card can screw up the tuning? Something to do with the output voltages?

I have noticed, Either plugging the Soundcard into another computer or even a different USB port on the same computer, causes the outputs to fluctuate. Meaning you have to reconfigure the op-amp board outputs back to 5 volts. Its very anoying.

The drivers seem to default everything out. also i think it depends on what other devices are plugged into that USB Bus. For example the other day i plugged an xbox360 game pad in my pc in the next socket along from the Scanner to play Laseroids..........Scanner went off.... So i messured the outputs from the OP-Amp. They has gone from 5volts to 1.3volts. I guess the game pad just drew that much power.

I imagine this could be solved by not using DC-DC Convertor. But a seperate 12volt supply to the OP-Amp

[keeperx]

DrLava... is there a way to make an amp board (rev2 maybe) that autocorected to 5v?
im thinking about adding something like this
http://www.electronics-lab.com/blog/?p=2335
to my hobby box so i can test very easily..
i would incorporate it in to the amp with a 12 position switch/knob
like this
http://www.web-tronics.com/10wa364.html
or this
http://shop.willyselectronics.com/br...fm/4,4795.html

[seanharrison]

DrLava... is there a way to make an amp board (rev2 maybe) that autocorected to 5v?
im thinking about adding something like this
http://www.electronics-lab.com/blog/?p=2335
to my hobby box so i can test very easily..

Nice idea keeperx

[thesk8nmidget]

that would be quite a nice little addition!

[keeperx]

yeah.. im an idea man. unfortunately i have a hard time turning my ideas into a reality...

[drlava]

If you plug another device in that draws so much current that your USB port supply sags below 5V, the computer should warn you about it and not allow it from happening. Unfortunately, many computers weren't designed this way. The 5V supply to the correction amp can be 'stiffened' by adding a regulated 5.0V wall wart supply in parallel with the existing connections. If the 5V supply stays at 5V, re-adjustment should not be necessary from computer to computer, as long as the sound card driver gain settings in the control panel are the same.