Results 1 to 7 of 7

Thread: Cambridge Tech 6650

  1. #1
    Join Date
    Oct 2007
    Location
    Huntsville
    Posts
    14

    Default Cambridge Tech 6650

    Hello all,

    I just bought some 6650 galvos off of eBay without the amps. Is there a way I can test (or have tested) these galvos to make sure they are in working order before I buy amps? Also, does anyone have any data for these guys, like pps? It's been a little hard to find info on these.

    Thanks,
    Keibot

  2. #2
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,351

    Default

    Quote Originally Posted by Keibot View Post
    Hello all,

    I just bought some 6650 galvos off of eBay without the amps. Is there a way I can test (or have tested) these galvos to make sure they are in working order before I buy amps? Also, does anyone have any data for these guys, like pps? It's been a little hard to find info on these.

    Thanks,
    Keibot
    call the cambridge factory during working hours if your in the US, they generally kindly will fax a data sheet or send you a PDF , but they probably dont spec that OEM model for laser shows and thus no pps. The coil(s) is easy to test with a Ohm meter, but since there is no torsion spring, you cannot test them open loop to see if the bearings are good. The position sensor needs a cosntant current drive and therefore must be tested either with a controlled current source or a known good amplifer.
    If the amplifer is not already tuned for a 6650, you must preforn the tuning from scratch.

    That 3.5 mS step response for a small jump means these scanners are slow and designed to move a big mirror around very precisely over a large angle. After some simple math I'm getting a 285 hz first resonance, thats a moderatly slow galvo.
    ~150-200 PPS if they do mean 3.5 milliseconds . A 6810 is .4 mS , so your
    3.5 / .4 = 8.8 so your almost 9 times slower then the industry standard.

    See:

    http://www.camtech.com/products/6450/6650.html


    Steve Roberts

  3. #3
    Join Date
    Oct 2007
    Location
    Huntsville
    Posts
    14

    Default

    Steve,

    Thanks for the quick reply. I picked these 6650s up just to play around with. I'm thinking of only using these for aerial grids with bounce mirrors around a night club, so I wouldn't think they have to be really that fast. Please correct me if I'm wrong...

    Once again thanks for your time and knowledge.

  4. #4
    Join Date
    Jul 2006
    Location
    Connecticut, USA
    Posts
    2,478

    Default

    i am by far NOT a super pro or anything, but if all your looking to do with these scanners is just basic aerial effects, these should work fine.

    beam positioning and simple basic "fans" i am sure will be simple. although some fans and/or "liquid skies" will probably strobe a little due to the relatively slower scan rates.
    give it a shot though, if its pathetic, go bigger!
    -Marc

  5. #5
    Join Date
    Oct 2007
    Location
    Huntsville
    Posts
    14

    Default

    Marc,

    Thanks also for your input. I'm assuming that these will work fine for what I'm doing. Like I said, it's for a club that I do shows at alot and all they want is a couple of different grids to bounce around. I had been thinking of building an enclosure strictly for them to permanently install. So when I bring the laser in all that I have to do is run fiber optic up to the projector. These were cheap and should fit the bill.

    Any suggestions on amps anyone?

    Thanks,
    Keibot

  6. #6
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,351

    Default

    I have some amp schematics hosted on a friend's web site. Cambridges engineers are very friendly, give them a call about the feedback, odds are you just need a single ended current limited 12V to drive the feedback sensor in the galvo, it will then output two weak currents that you run into a low pass filter to get rid of residual RF, then into a current to voltage converter to get the feedback signal.

    As for commercial boards, I dont know , you might have to get them from cambridge as all the laser show stuff I know of that uses cambridge uses optical feedback. A GSI style Laser Media LM22SDA WITH A FEW MODS might be a option.
    as theya re designed for capacitive (RF) feedback.

    If your rolling your own:

    Go West young Man, (ie these are hosted on a server in Seattle area)

    http://www.skywise711.com/lasers/scanner/scanner.html

    on the cambridge schematics
    U4A, U4C, and U4B format the feedback currents from the OPTICAL FEEDBACK photodiodes into voltages , since you have similar currents coming out of the capacitive feedback in your new galvos, that means you just need a LC filter in front of the inputs to get rid of any residual RF from the capacitive sensors (they run at a few megahertz) and you should be good to go. The cambridge AGC circuit that normally drives the LEDs may have to be rplaced by something simpler.

    I AGREE, These will be great for feeding bounces and sheet scans etc.

    looks like its time for me to post some feedback demodulator circuits some place. (hint hint Spec, I need a gallery for schematics!)

    Steve

  7. #7
    mixedgas's Avatar
    mixedgas is online now Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,351

    Default

    [QUOTE=gottaluvlasers;34016]i am by far NOT a super pro or anything, but if all your looking to do with these scanners is just basic aerial effects, these should work fine.

    Sorry, I wasnt thinking when I replied that way. Maxima mea culpa.

    Steve Roberts

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •