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Thread: Converting my TTL laser to analogue

  1. #1
    Join Date
    Oct 2007
    Location
    Sydney, Australia
    Posts
    155

    Default Converting my TTL laser to analogue

    Hi laserists

    I've got a nice little chinese scanner (darn it - PROJECTOR - the scanner is the thing you see in the supermarket!) that isn't half bad (its no home made beast, but it does have decent galvos in it, and ILDA - I use it with a frame streamer express). I'm thinking of upgrading all the drivers to analogue (flexmod p3's to be exact). Now I know its simply a matter of finding the current of the 3 diodes (red, violet and green) and setting flexmods to match, but the thing that worries me is some diodes are case negative, others case positive, and as for the violet which I am replacing with a 445, case isolated.

    Is it safe to probe the leads of a diode and the projector case (obviously with the projector turned off) with a DMM on the continuity test range to find out which diodes will need to be isolated from the case to prevent a short? I dont want to blow up diodes, just by testing them. I may also replace the crappy 650nm red with a 640 - Have the issues with the laser wave 640's been resolved? I'm thinking of fitting a 400mw, matching that with 400mw 445, and upping the green to ~150mw ish to balance out. Going this route I would only need to flexmod the 445 - the other 2 lasers come with analogue as standard.

    I'll be removing the SD card player board from the laser (its practically useless), and probably the DMX512 stuff as well, although this might be handy for when I dont want to lug a whole ilda system to say a friends party. The inbuilt patterns got pretty boring though, couldnt wait to get down to jaycar once my FSX2 arrived to get an ilda lead and try some computer based shows!

    Next question:
    Whats the difference between a high side driver and a low side driver? I'd assume that a high side regulated current on the positive side of the diode, and a low side driver has the regulator on the negative leg of the diode. (how I got my ham radio license I dont know - I need to go back and study my basic electronics!)

    Thanks
    Ben

  2. #2
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    3,730

    Default

    Quote Originally Posted by dash8brj View Post
    Hi laserists

    I've got a nice little chinese scanner (darn it - PROJECTOR - the scanner is the thing you see in the supermarket!) that isn't half bad (its no home made beast, but it does have decent galvos in it, and ILDA - I use it with a frame streamer express). I'm thinking of upgrading all the drivers to analogue (flexmod p3's to be exact). Now I know its simply a matter of finding the current of the 3 diodes (red, violet and green) and setting flexmods to match, but the thing that worries me is some diodes are case negative, others case positive, and as for the violet which I am replacing with a 445, case isolated.

    Is it safe to probe the leads of a diode and the projector case (obviously with the projector turned off) with a DMM on the continuity test range to find out which diodes will need to be isolated from the case to prevent a short? I dont want to blow up diodes, just by testing them. I may also replace the crappy 650nm red with a 640 - Have the issues with the laser wave 640's been resolved? I'm thinking of fitting a 400mw, matching that with 400mw 445, and upping the green to ~150mw ish to balance out. Going this route I would only need to flexmod the 445 - the other 2 lasers come with analogue as standard.

    I'll be removing the SD card player board from the laser (its practically useless), and probably the DMX512 stuff as well, although this might be handy for when I dont want to lug a whole ilda system to say a friends party. The inbuilt patterns got pretty boring though, couldnt wait to get down to jaycar once my FSX2 arrived to get an ilda lead and try some computer based shows!

    Next question:
    Whats the difference between a high side driver and a low side driver? I'd assume that a high side regulated current on the positive side of the diode, and a low side driver has the regulator on the negative leg of the diode. (how I got my ham radio license I dont know - I need to go back and study my basic electronics!)

    Thanks
    Ben
    Hi Ben.

    I would not continuity test the diode connections... You can carefully (and wearing suitable safety goggles) measure the voltage of each connection with respect to case ground to determine the drive method (high side or low) while the laser is illuminated. If you replacing the modules, why bother?

    Yes, high side drivers current regulate the positive side of the diode and visa versa.

    High side drivers are required when the LD negative is case bonded.
    This space for rent.

  3. #3
    Join Date
    Oct 2007
    Location
    Sydney, Australia
    Posts
    155

    Default

    which is the case with the LOC and BR diodes

    So all things aside, if I replace the 3 drivers in my laser projector with flexmods, it would be a cheap way to get analogue.
    I will be upgrading the blueray diode to a 445, simply because its such a cheap excercise. The red laser went pop, and needs replacing, I will use a LOC for this.

    My modules have a 20mm dia hole perfect for the 18.5 o-like module cases. That gives a bit of play, but some silver thermal tape would solve that problem.

    I've sat down and thought about it, and after replacing the blown red, upgrading the blue to the 445, and changing the drivers to flexmods, this is as far as I want to go with this projector - I'd rather get started and put 640's and expensive bigger greens into my own homebuilt projector.

    This (the one I am upgrading) projector will be my home testing "plaything" and I'll keep the nicer home built one for parties and such (and the plaything can works as a secondary projector)

  4. #4
    Join Date
    Apr 2009
    Location
    Adelaide , Australia
    Posts
    70

    Default

    Hi Ben,

    Re the Laserwave 640 ... I bought a 400mw LW 640 Red module from Dave (Lasershowparts.com) back last september and have'nt had the talked about alignment issues with my module ... 640 definately the way to go if u want impressive bang for your bucks

    Good luck with your project

    Cheers,
    Brett

  5. #5
    Join Date
    Oct 2007
    Location
    Sydney, Australia
    Posts
    155

    Default

    awww thats great news - the 640 400mw looks really good value for money from LSP, and it will be almost twice as bright as a 650, or 2.5 times as bright as a 660. (from what I have read), yet doesnt have the torch beam of a 635. It should mix well with 300 mw of green and 400 mw of 445.

  6. #6
    Join Date
    Sep 2010
    Location
    Utrecht The Netherlands
    Posts
    721

    Default silver tape

    [QUOTE=dash8brj;177894]
    My modules have a 20mm dia hole perfect for the 18.5 o-like module cases. That gives a bit of play, but some silver thermal tape would solve that problem.

    QUOTE]

    i orderd kapton tape from dealextreme.com, low price and free shipping, it is like the tape from 3M, insulates electricity but conducts heat.

    here is the link
    https://www.dealextreme.com/details.dx/sku.5101

    Michel

  7. #7
    Join Date
    Oct 2007
    Location
    Sydney, Australia
    Posts
    155

    Default

    cool - thanks for that - that should avoid another diode going pop due to (what I believe) was an earthing issue.

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