LFI Player + DAC problem

[mixedgas]

Where are you located? Perhaps another PL user is close and has the gear to help you?

John, make him a frame that is a ramp in the X axis and a pulse centered on the middle of the ramp in the RGB channels. Then he could feed the RGB one at a time into the Y axis and it acts as a crude scope. See attached PDF.

Steve

[dchammonds]

No matter how I adjust pots I cannot achieve 5V when playing max.wav and 0V when file is paused.

What range of output can you get? I don't have the right software to see your print...
Any way you could scan it as an image?

[ReNNo]

Galvos work within the entire +-5V range. Lasers only work within the 0+5V range. The output from these color channels on the sound card DAC is still +-5V but the software only sends values that keep it in the positive range. If the output is inverted, the software will essentially be driving the lasers only with negative signals. I don't know if this is your problem or not. But, since all of the channels are identical electronically, you should be able to easily compare and test. As a quick test, route your XY channels to your RG channels and display a test pattern. You should have laser output. If not, you have other issues that you need to resolve.

Ok, I'll try tomorrow...

Where are you located? Perhaps another PL user is close and has the gear to help you?

I'm from Bosnia, don't know any laser enthusiast near me.

What range of output can you get? I don't have the right software to see your print...
Any way you could scan it as an image?

For example.... When I adjust opamps to give me 5V when playing max.wav then when I pause file I get 9.5V.

There is no way that I can adjust it to 5V when playing max.wav and still have voltage under 5V when pause it.

Yes, here is in PDF format...
http://www.speedyshare.com/files/24601242/Zavrsen.pdf

[drlava]

The problem is you're basically using a laser driver schematic instead of a correction amp for the color channels. If you use a correction amp (as posted here) THEN a laser driver circuit, you will have the adjustment range required.

[ReNNo]

And what is problem in my schematic?

Can I just modify it?

[drlava]

You should be looking for 5V and 0V from the output of the second op-amp in your schem. for each color channel. The rest after that in your schem. on the color channels is intended to be connected directly to a diode, unless you meant to build a diode driver as well, that part is unnecessary and should be removed.

[ReNNo]

I built everything...



I only need to connect lasers, sound card and power supply and that is it.
It should work, but as you can see I cannot make it work.

[drlava]

It appears we are having a language barrier here. Do you understand what I said?

[ReNNo]

Yes, it's probably language barrier.

You say that I need to get 0-5V at output of second opamp.
Yes, I can get these values. But cannot get 5V when paying max.wav, everything is backwards.

I also need cheap way to make analog driver, that is why I integrated everything on PCB.

[dchammonds]

Yes, it's probably language barrier.

You say that I need to get 0-5V at output of second opamp.
Yes, I can get these values. But cannot get 5V when paying max.wav, everything is backwards.

I also need cheap way to make analog driver, that is why I integrated everything on PCB.

Digital signals can range from negative to positive and max.wav is full negative, this was done because many correction amps invert the signal, and you need 0 to +5v to drive the colors.

Your first stage inverts, but the second stage inverts again (at a gain of one) so max.wav will cause the output to drop when it is played.

From looking at your schematic and the results you are getting, I think I understand why the X-Y circuit is working (its output is differential), it might be usable as is. For the color circuits, I agree with drlava that you need to have the correction amp stage he mentioned to drive them.

Dean