USB Audio DAC mod + LaserBoy Correction Amp

[James Lehman]

Take a look at the first picture of the first post in this thread!

http://www.photonlexicon.com/forums/...ead.php?t=4920

GRIBYX, dude!

James.

[dar303]

I have my Laserboy-Spaghetti --> USB DAC setup working but when I compared it to the output from the DMX/Auto-card that came with my 30k scanners the output angle looked very small.
When I checked with my scope i measured +/-5V from the USB DAC and +/-10V from the DMX-board! No wonder it was small a scan angle!

The signals are both singel ended so it hasen't anything to do with the DMX-board using balanced lines. I tried to invert the signal from the DAc and feed it to the - input on the scanner driver but that didn't work either.

[carmangary]

Yes, most scanners need +-10v but the LaserBoy dac mod won't go that high. You might squeeze out +-6 or 7 but that's it. You can adjust your scanners input gain to work with +-5v but that isnt the best solution because if you hook to a normal DAC you might hurt something.

[James Lehman]

Yes, most scanners need +-10v but the LaserBoy dac mod won't go that high. You might squeeze out +-6 or 7 but that's it. You can adjust your scanners input gain to work with +-5v but that isnt the best solution because if you hook to a normal DAC you might hurt something.

Hmmmm. It could! Interesting!

But, since it does not, if a sound card DAC + LaserBoy Correction Amp is the only DAC you have, you should adjust your scanner's input gains to go to whatever you call full swing at a peek-to-peak voltage that is good for you! That's why those adjustments are there!

James.

[dar303]

I'm propably going to make a small board with a couple of 2xgain amps and put in the projector since I might need the DMX-card. Or maybe attenuate the output from the DMX-card and turn up the driver gain. I'ts really no problem for me but I thought other builders would like to know.

[carmangary]

You may also be able to by pass the LaserBoy DC-DC converter and feed +-12V into the op amps and then you would be able to reach the required +-10V. That would be the simplest solution although it would mean you would need an external power supply or maybe tap off the DMX boards power. Your DMX board might already have an output for +-15V on it that could be used.

[James Lehman]

Those +5VDC input DC/DC converters come in different output voltages, with exactly the same pin out; +/-12VDC & +/-15VDC. The only trade off is output current.

James.

[carmangary]

Those +5VDC input DC/DC converters come in different output voltages, with exactly the same pin out; +/-12VDC & +/-15VDC. The only trade off is output current.

James.

Do you have a part number? Maybe I'll swap mine out. But I can't see the part number the way it is installed right now.

[James Lehman]

http://www.micropowerdirect.com/Page...C%20D100E.html

Take a look at the D106E. That's what you have. The D107E would be the +/-12VDC.

These guys have a $25 min order. This part is about $4.

James.

[carmangary]

Cool. Thanks. I asked for a free sample so we'll see how it goes.