first laser project - soundcard DAC trouble?

[daderaide]

I removed the 47uf caps between the output channels of the chip and the jack :-P whatever their proper name, I'm certain that that step of the process is correct.

[james]

How are you playing the waves? What app?

James.

[daderaide]

I'm using spider player

[james]

I'm using spider player

Whooo Hooooo!

Now get Audacity so you can open the waves and actually see what is in them! You will note that the information in the waves is inverted. So negative values in the color signals will result in positive voltages coming from your LaserBoy Correction Amp.

Since you are using Spider Player, are you measuring the correct voltages on the color signals when you play the big white circle?

Did you make a wave of the big white circle using LaserBoy and frame 10?

James.

[NobleGas]

I have modified countless sound cards of different makes and I have no idea of what you are writing about.

There are DC DE-coupling caps that block the positive DC voltages found on direct from DAC signals before the output jacks.

James.

Decoupling caps are used to decouple supply lines, typically located near each chip and connected between +ve supply and 0V.
Coupling capacitors are used to couple AC signals between the stages of a circuit, also known as DC blocking capacitors.

[james]

Maybe we're just using different terminology.

I would call the output caps de-coupling because they de-couple the direct voltage from the DAC output and convert absolute voltage to change in voltage over time.

I would call caps from supply voltage to ground filter caps to smooth out any noise on the power supply voltage.

[NobleGas]

Maybe we're just using different terminology.

I would call the output caps de-coupling because they de-couple the direct voltage from the DAC output and convert absolute voltage to change in voltage over time.

I would call caps from supply voltage to ground filter caps to smooth out any noise on the power supply voltage.

Perhaps, but when you're discussing these things with an electronics engineer, best to use the correct terms
Anyway, it would appear that daderaide has probably done the right thing and picked up his signals ahead of the coupling caps, so he should be DC coupled into his scanner amps.

[daderaide]

I didn't make the wav using laserboy. I just used the one that was included in the zip file from the other forum post. I've now uninstalled and reinstalled several different usb audio drivers. The one that I'm on now seems to be working very well with the wav file. all of the different files show a big circle that uses the entire scan area. when i try the ilda file in spaghetti i get this now:



with the wav file played through spider player it looks like this:




If I play a show that has music in it, you can actually hear the music vibrations in the galvo :-( and then image turns all wiggly with the waveform of the music.

[james]

Try making some waves of other frames in LaserBoy that are recognizable images and make sure your X and Y are in the right place. If you have them reversed, the image will be sideways.

You can't tell if a circle is sideways!

Post some more pics!

James.

[daderaide]

I'm starting to feel like it's time to scrap this and just buy another commercial dac