Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Buy Site Supporter Role (remove some ads) | LPF Donations

Links below open in new window

FrozenGate by Avery

Sound card DAC tutorial

arcaneinsomniac said:
So there's no way to get fast analog current control without bleeding off extra power as heat? I guess standard methods to do it (buck circuit?) has inductances and properties which make it too slow to keep up?

So I got an email saying my order from Nautilus Integration has been cancelled. I guess DrLava doesn't have any more laserboy PCB's. I think my digikey order is in, though. I guess it's breadboard time.
Click to expand...

The dimming circuits for many bucking topology circuits simply have a bypass transistor in parallel with the laser for PWM. It ends up using the same amount of power no matter what.

PWM is ultimately what you'd have to use to reduce the brightness without (much) heating. The problem is, of course, that you need a PWM base period that is far smaller than what you intend to have projected or you'll see those nasty dashes. At even a lowly 20kpps, you're looking at a very fast PWM.

Another thing to try would be using an acousto-optic modulator or something of that nature. It still may not be fast enough.
 





Okay I got a breadboard X-Y correction amp built:

correction_amp_breadboard.jpg


There is a pin header on the driver boards labeled +15 0V -15, it seems to be a +/- 15V supply but I have no need for them. What is this for?

Also, what exactly do I connect the input to the scanner? It takes 3 pins for input for each galvo. The SpaceLas PDF labels them +X -X 0V and +Y -Y 0V.

My correction amp has a ground and a single voltage output for X. Do I hook that up to +X? What goes to -X? is 0V the correction amp GND? Or is it -X?

I'm looking at ILDA spec now:

X: Controls the horizontal beam position. This is a bipolar analogue signal whose voltage range is 10V peak-to-peak differential.
A differential voltage level of -10V shall deflect the laser beam to the left side of the projection area. A differential voltage level of +10V shall deflect the signal to the right side.
A differential voltage of +10V occurs if the normal signal line has a voltage level of +10V with respect to the voltage level of the inverted signal line. When compared to the ground level of the differential driver, the voltage level of the normal signal line shall be +5V and the voltage level of the inverted signal shall be -5V.
Click to expand...

It seems to specify that the signal value is transmitted using a symmetrical differential signal where the voltage difference between the two opposite signals is between -10V and 10V and they are equally and oppositely changing from the 0V GND value.

This is not the signal being provided by the tuned correction amp, which (please please correct me if I am wrong) produces -10V for all the way to the left, and +10V for all the way to the right.

To satisfy ILDA I need a voltage that is in the middle to connect to the 0V pin...

My guess at this point is I skip the 0V pin and simply connect my correction amp's GND to -X, and the TL072 output for X to +X. Then I have a differential value which is the correct value.

Also I can't seem to find a link to download circle.wav.

Also, I cannot seem to get LFI to put out a waveform. I havent set up a sound card or anything yet but I should be able to hear something coming out of my headphones while playing an ILDA show but I'm getting nothing.

Edit: gonna start a new thread about LFI
 
Last edited:
hey guys i downloaded the cmedia driver i see a folder for vista and xp anything for windows 7? thanks guys
 
Hey guys, I'm using the audiolase dac and soundcard. Wired everything up, connected the SC to my laptop, did what it's been suggested in this thread and in the other one for win7 users, but didn't get an output. I want to get this going on LFI. Any other tips that might help on getting output ? When I plug in the dac, there are 2 devices recognized. One is digital and the other says Speakers. I have really no idea what to do lol. All new to this.
 
Last edited:
Silvershot said:
Hey guys, I'm using the audiolase dac and soundcard. Wired everything up, connected the SC to my laptop, did what it's been suggested in this thread and in the other one for win7 users, but didn't get an output. I want to get this going on LFI. Any other tips that might help on getting output ?
Click to expand...

The primary issue I had with LFI is you have to open the settings and check the "Laser On" checkbox and then it outputs sound. I believe ElektroFreak (OP) has updated the tutorial with this bit of info.

I was able to get my scanner running, though LFI does like to crash a bit. One of these days, once I get a setup to mount my scanner and optics and lasers I'll probably start working on a superior open-source software solution for quick&easy beamshows. Stay tuned.
 
arcaneinsomniac said:
The primary issue I had with LFI is you have to open the settings and check the "Laser On" checkbox and then it outputs sound. I believe ElektroFreak (OP) has updated the tutorial with this bit of info.

I was able to get my scanner running, though LFI does like to crash a bit. One of these days, once I get a setup to mount my scanner and optics and lasers I'll probably start working on a superior open-source software solution for quick&easy beamshows. Stay tuned.
Click to expand...

I did check the laser On option. Not sure what I'm missing. Do you remember chaning anything else? Are you on win7?
 
Last edited:
Use the "Speakers" output; the digital version will output PCM which is not what you want. Also make sure that the speakers are set up for 7.1 surround sound with full-range as per the tutorial or else you'll get weird mixing.
 
Bionic-Badger said:
Use the "Speakers" output; the digital version will output PCM which is not what you want. Also make sure that the speakers are set up for 7.1 surround sound with full-range as per the tutorial or else you'll get weird mixing.
Click to expand...

Hello,

I am also working on a soundcard dac. I have set the soundcard up correctly but I still get some channel mixing. I can hear a weak signal from the left channel onto the right channel (It's the same on all channels) Could it be a bad soundcard or is there something else wrong?
 
laser15 said:
Hello,

I am also working on a soundcard dac. I have set the soundcard up correctly but I still get some channel mixing. I can hear a weak signal from the left channel onto the right channel (It's the same on all channels) Could it be a bad soundcard or is there something else wrong?
Click to expand...

Are you able to post or PM me pics of your DAC setup and screenshots of your audio card settings? Hardly anyone ever does that, but I'll ask anyway since they would be absolutely golden in terms of helping to diagnose problems.
 
Last edited:
You must log in or register to reply here.





Back
Top