USB Audio DAC mod + LaserBoy Correction Amp

[Things]

I reckon the problem is purely that the DAC output is only single ended. I also had distortion problems with my Scanpro's, but I did at one stage managed to get their tuning pretty good, but I still had to live with the small scan angle. I believe it would be possible to convert the soundcard DAC's single ended output to differential with an opamp and a few simple components ...

[DPSS]

one final idea before scope.. you should double check your usb sound card control panel volume levels to make sure the proper adjustments are still at the same level (max) that they were when you set the gains using max.wav.

I've triple checked and they're ok.

It might be a bit of a drive (or ride the train), but you might want to try to get together with some of our other European members and connect them to a different controller. I don't know of anyone else in Spain, but I know we've got members in Belgium, Germany, and Italy... Maybe one of them would be willing to lend a hand.

As for one amp having slightly more gain than the other, that's not uncommon at all. But if you can't get more than 10-15 degrees out of the scanners, then that is a problem. As Dave said though - there are too many potential variables right now.

Adam

Belgium, Germany, and Italy? Man, that would be one hell of a long drive to just test the scanners.
I think for the moment I'll try and figure it out here at home. Thanks for mentioning it though.

I reckon the problem is purely that the DAC output is only single ended. I also had distortion problems with my Scanpro's, but I did at one stage managed to get their tuning pretty good, but I still had to live with the small scan angle. I believe it would be possible to convert the soundcard DAC's single ended output to differential with an opamp and a few simple components ...

Hmm, but it doesn't seem to happen to everyone. So why?

Still searching for an o-scope.

Domingo.

[mixedgas]

Still searching for an o-scope.

Domingo.[/QUOTE]

Drag your system to a local university electrical engineering or physics department. Odds are you'll get a free checkout on their scope as research can be very tedious and they wont mind a small distraction. Call Ahead, they live on a tight schedule, tell them you need 5 minutes of low speed scope time and your setup is small and portable.

Professors used to paying 800 Euros for a DA card will like the 24$ solution and possibly copy it for lab work.

Steve

[DPSS]

Thanks Steve.
I'll give it a try.

Do you know if one of >these< or something similar would be any good?

Domingo.

[drlava]

it would be able to help you in this case but that's no substitute for a real scpe

[keeperx]

do an ebay search for "oscilloscope 20mhz" that way your more likely to see listing for solid state scopes..

buy the cheapest one that has 2 inputs and xy mode..

if your unsure just post us a link

[keeperx]

also FYI
http://scopeonpc.googlepages.com/scopeonpc
"ScopeOnPC is a free software that uses the PC parallel port and an ADC (Analog To Digital converter) circuit to turn your PC into a full featured ocliloscope."

http://scopeonpc.googlepages.com/scopeonpc4

that SHOULD work just fine but i have no experience.

[mixedgas]

par port dacs are nasty in a windows enviromment due to windows timing issues

known good performer:

http://www.parallax.com/Store/Microc...me,ProductName

You need dc coupling, and the par port scope does do that.

Steve

[mixedgas]

also FYI
http://scopeonpc.googlepages.com/scopeonpc
"ScopeOnPC is a free software that uses the PC parallel port and an ADC (Analog To Digital converter) circuit to turn your PC into a full featured ocliloscope."

http://scopeonpc.googlepages.com/scopeonpc4

that SHOULD work just fine but i have no experience.

The 10k/100K pulldown bias is iffy for DC coupling with a negitive going signal. But its cheap and far better then nothing. try to run it on a differnent machine then the laser software, to avoid windows timing issues, but if it works, it may solve a probelm for a lot of people. there are sound card scope programs, but you'd need to remove the caps on the sound card input and bias it to the middle, the same problem you have now with the sending card.

Do you do any circuitry at all? A simple ramp generator turns your galvos into your scope.

BINGO, I must now post a good cheap linear ramp circuit to help others.

Steve

Steve

[DPSS]

Hi guys,

Sorry about my absence for the last week, but I've been really busy at work and I haven't had much time to do anything else.
I've finally found someone willing to let me use there oscilloscope so, for the moment, I won't be buying or building one.
Now all I need is a little help from you guys to know what I have to measure and how to do it correctly.

Domingo.