Power supply?

Oh okay, a separate pc psu...

Depends on what you have installed of course, but it seems a bit overkill for me. I'm leeching the power for the correction amp from the galvo psu (thats -+24, regulated down to -+12v). To power the actual lasers i'll get a little extra power supply, something like 6v/1a should suffice.

thats not overkill and it would even look a bit professional when rigged up with a pc psu but there are these crazy magical things called voltage regulators we use in electronics land but those are of course for more of a custom build i guess idk w/e floats your boat

Ah well, its just what you prefer and see as practical. I figured the 24 volt power supply for the galvo's rated at 1 amp could spare a couple of 10s of mA to power the compensation amp opamps. So far, no problem there.

Powering the lasers from usb didnt seem feasible to me since it'd require more than what the bus is supposed to provide. Also, it has the additional problem that powering anything from the usb bus does cause slight voltage drops, that in turn result in changes in the souncard outputs. That way, the blanking actually messes up the scan signal in practice.

Personally i dont like ATX power supplies for electronics projects. They can work, but many of them require a sizeable minimal load on the 3.3 and/or 5 volt lines to operate reliably.

You can get a decent PSU off of Ebay for less than $20.

This is what I have powering my lasers and fans.

12V 3A DC Universal Regulated Switching Power Supply - eBay (item 200401883170 end time May-02-10 18:00:41 PDT)

Looks nice enough - almost exactly like the one i got with my scanner set. The voltage can be adjusted quite a bit on most of those, so for powering the lasers it could also be interesting to get a 5 volt model and turning that slightly up.

well generally all lasers are powered via 5v, fans run on 12v so rather than having two psu get a computer psu which outputs 5v and 12v.

its not OTT by any means

How do you figure that the 500mA provided by USB won't power your sound card and correction amp? If they're drawing more than 1/2A there's a problem..

I figured the USB power will not run the -lasers-. You could easily power the correction amp from usb using switching voltage converters. I just run the correction amp on 12 volts downregulated from the 24v scanner psu, since its already there and regulating down to 12 volt with 7812 and 7912 regulators is easier then using a switching supply to make those voltages from the 5v usb power.

Oh.. I didn't realize you were trying to drive the lasers using USB also.