USB Audio DAC mod + LaserBoy Correction Amp

[keeperx]

well the best person to answer that stuff is DrLava and James.

basically i like to start by measuring one channel at a time and tuning the bias to 0v and the gain to a 5v swing on each

if there is clipping in X and Y you will see flat spots at the top or bottom of your wave form


the top wave in this pic is not clipping the bottom one is clipping VERY BADLY.




this is what digital clipping looks like.


Once thats all looking good, throw the scope in XY mode and play some test patterns.

for X and Y make sure scope is set to DC or else it will try to center everything

[DPSS]

Thanks Keeperx, It seems It's finally not going to be possible for me to use the oscope I was promised so I've decided to keep trying to get a cheap one from ebay a little longer, maybe I'll get lucky.

What do you think about >THIS< one, or >THIS< one, or >THIS< one.

Domingo.

[keeperx]

if this
http://cgi.ebay.es/PHILIPS-PM3217-OS...0|293:1|294:50
is in good condition, then thats all you need.

it does 50Mhz and you are only measuring in Khz so its PLENTY

[DPSS]

Great, Thanks.
I'll let you know when I get somewhere.

Domingo.

[DPSS]

Hi,

Just droped by to let all of you that have been helping me with my scan angle problem know that I ended up buying a second hand scope from ebay, and just yesyerday I had time to measure the correction amps outputs with it. After setting the trim pots on the correction amp correctly using the scope I'm getting about double the scan angle than before, so it's looking good. Turns out my meter was malfunctioning and the readings I was getting were all wrong .
Anyway, I'm waiting to receive another probe for using together with the one I allready have to play some patterns with the scope in XY mode. I'll post some pics as soon as I get it.
Thak you all very much for your help.

Domingo.

[drlava]

Glad you got it sorted out. for your next meter, buy a fluke 87 or similar! indispensible

[keeperx]

dont be surprised if when you put the scope in xy mode, the y channel looks a little wider than the x channel, or vise versa... thats normal..

make sure the range is correct when the scope is in wave form mode... the xy mode is not always 100% accurate.. but you should still see pretty patterns

[DPSS]

Glad you got it sorted out. for your next meter, buy a fluke 83 or similar! indispensible

Thanks, I'll check it out.

dont be surprised if when you put the scope in xy mode, the y channel looks a little wider than the x channel, or vise versa... thats normal..

make sure the range is correct when the scope is in wave form mode... the xy mode is not always 100% accurate.. but you should still see pretty patterns

Thank you for pointing it out, I can't wait to receive the probe and give it a try.

Domingo.

[ElektroFreak]

Allright, so I've been lurking here for some time and I just finished incorporating this sound card DAC solution into a scanner of mine. I'm using spaghetti, and the setup works perfectly 90% of the time. By 90% I mean that when I view the ILDA test pattern it is almost perfect axcept for the circle in the middle. Try as I might I can't seem to find a speed that will render it correctly. It stays inside the square, and it isn't a circle so much as a horseshoe-shaped curve. All animations look perfect, except occasionally I'll find one that won't render curves properly.

What I'd like to know is if this is because of detuned amps/galvos, or if it's due to the fact that the DrLava correction amp doesn't drive the galvos hard enough. I know that they usually get a +-10V swing, and with the correction amp they're only getting +- 5V swing. I'd rather not retune my galvos to run at +-5V, so if that's the reason I'll just deal with it and only use frames that look good (which is most of them). The galvos are SP20s that are brand new. All frames from my cheepie DMX board look perfect, so I assume they were properly tuned from the factory (or at least very close to it).

Any help from the experts would be very much appreciated. Thanks in advance..

[drlava]

As the output speed can go down to 2kpps or less, you should be able to find a speed where the circle looks circular. What lasers are you using?