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Thread: Newbie blanking question

  1. #1
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    Default Newbie blanking question

    Hey guys, I've been a part of this forum for almost a year now but i havent been checking it out until now. my laser addiction is getting worse so i figured its time to get the ball rolling. i've got a 310mW RGV laser projector that ive been playing with but it was very cheap and now im interested in building my own projector. ive been reading up on laser modules, galvos, drivers and power supplies but the one aspect im still not very familiar with is blanking. i know the difference between digital and analog blanking and im interested in using analog blanking for my (future) projector, but i dont know what is used to accomplish this. any links to products and/or detailed descriptions on how this is done would be greatly appreciated. ill have many more questions when i actually start to build the thing im sure, but right now i just want to get as much "book knowledge" on laser projectors as possible. thanks for your help!

  2. #2
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    Default

    Digital vs. Analog.

    Typically the laser you purchase will be designed one way or the other. Just make sure you check the spec sheet to make sure your getting analog modulation.

    If your trying to build your own laser, then you will need a driver that is capable of analog modulation and laser that responds well to it. For example some diode pumped greens also known as 532nm, don't respond well to analog modulation.

    By the way welcome to the forum. If you can make it to a LEM Laser Enthusiasts Meeting you will learn a lot. The big one in the US is called SELEM. There is one this weekend in Florida. Tell us about yourself, how long have you been into laser, where are you located. This way we can put you in touch with someone in your area.

    Edit: Sorry I just saw your in Arizona.
    Lazerjock

  3. #3
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    Smile Re: Newbie blanking question

    Agree 100% with everything Chris said above.

    Key point to remember: it's the laser driver that determines the type of modulation (analog or TTL) that you have. However, in some cases you can replace (or upgrade) the driver to get analog modulation.

    I suggest you get in touch with Beamman here on the forums. He's in Arizona as well, and I'm sure he'd appreciate the chance to talk shop with you over a beer or two.

    Adam

    PS: Welcome to the forums!

  4. #4
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    Default Re: Newbie blanking question

    Hey, thanks for the replies. I guess I've been interested in lasers since I got my first laser pointer as a kid but I didn't actually consider getting serious about them until I saw a home laser show on YouTube last year. I was so amazed that I decided to see what was involved in putting one together and since I'm a bit of a tinkerer with an interest in mechanics and electronics I thought it would be fun. I purchased a cheap rgb laser on eBay from china (violet not blue) and have had fun with that. I'm assuming it is digitally modulated because it only has 7 color capabilities. Just to make sure we're on the same page, there are several drivers involved in laser projectors, correct? There will be one for each galvo and one for each laser. And the blanking is controlled by the laser drivers? So each galvo and each laser is connected to it's respective driver and the drivers are powered by one or more power supplies? And it's the drivers that translate the input signals from the computer to usable data for each component? If all that is correct, then my next question is what are some good beginner drivers? I will probably be looking into lasers up to 1W. They don't have to be top notch seeing as how this is an experimental project. My only requirement is that they are capable of analog modulation. I'll be sure to check the lasers I purchase to make sure they are compatible. Thanks again for your help.

    Ps. I'm definitely interested in meeting anyone in phoenix or the nearby area who shares my interest in lasers. I've tried finding people but with no luck. Thanks again for all your help. -Luke

  5. #5
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    Default Re: Newbie blanking question

    Quote Originally Posted by ZeroPoint View Post
    I'm assuming it is digitally modulated because it only has 7 color capabilities.
    Luke,
    You have done your homework. You nailed it on every one of your points.
    Yes with only 7 colors you have digital modulation also known as TTL.


    Quote Originally Posted by ZeroPoint View Post
    Just to make sure we're on the same page, there are several drivers involved in laser projectors, correct? There will be one for each galvo and one for each laser. And the blanking is controlled by the laser drivers? So each galvo and each laser is connected to it's respective driver and the drivers are powered by one or more power supplies? And it's the drivers that translate the input signals from the computer to usable data for each component?
    Yes all of that is correct. I'm impressed!

    Quote Originally Posted by ZeroPoint View Post
    If all that is correct, then my next question is what are some good beginner drivers? I will probably be looking into lasers up to 1W. They don't have to be top notch seeing as how this is an experimental project. My only requirement is that they are capable of analog modulation.
    I would recommend Dr.Lava's FlexMod Driver. They are well built and the right price. FYI any driver that can do analog can do digital/TTL as well.

    Quote Originally Posted by ZeroPoint View Post
    I'll be sure to check the lasers I purchase to make sure they are compatible. Thanks again for your help.
    I think you may have missunderstood this part. If you intend on building the laser from components (the laser diode, optics, housing, and driver) then you would use something like Dr.Lava's FlexMod driver. He is a member of this forum. Here is a link to his site.
    http://hacylon.case.edu/ebay/laser_diode/FlexModP3.php


    If you purchase a lab style laser, it will have the driver built in. This is where you would verify it is capable of analog modulation. You simply supply power and an input signal to make it modulate. Some people like my self have taken a digitally/TTL modulated laser and bypassed its built in driver then added a analog driver to "convert it" to analog. This is risky and can be difficult, but can save you a few bucks. Keep in mind you can blow up the laser diode if you don't know what your doing. I've killed several personally. I would not recommend trying this. Usually we do this to old lasers. If you are going to buy a new laser just spend the extra few dollars and avoid the risk.

    Lazerjock

  6. #6
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    Default Re: Newbie blanking question

    Thanks lazerjock! And you're right, I did misunderstand that point. I thought you were referring to the diodes themselves being compatible with analog. I am definitely interested in being able to build my own module in which case I would check out drlava's flexmods. Otherwise, I'll make sure the modules I buy are analog compatible. I guess I was also thinking that there was another driver or something that I would connect the prebuilt module to, but that's not the case? What then are the modules connected to other than the power supply that modulates the voltage to provide blanking? or is that done from the computer software through the power supply itself? I guess I was thinking that the power supply was separate from the computer signal and only supplied a constant voltage that was modulated by a separate component. I think I'm starting to get it though thanks again for your help

  7. #7
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    Default Re: Newbie blanking question

    You're getting it! Yes there is a seperate device that connects between the computer and laser drivers, and scanner amp's. It's the DAC Digital to Analog Converter. Several companys make them, or you can make your own using a modified sound card.

    So the signals are created in the computer using software. Typically the software is included when you buy a DAC. If you choose the sound card route there are several programs out there that work with it and other DAC's on the market. Then that signal is sent to the DAC which canverts the signals to analog or TTL if that is what your laser requires. Most DAC's output a minimum of these signals: X scanner, Y scanner, Red, Green, Blue. There are several more, but we can cover that later. There is a standard pin out that we use called ILDA. It uses a DB25 connector. This allows me to connect my projector to someone elses DAC. We do this at laser enthusiast meetings (LEM's). Once the signal leaves the DAC it goes to the scanner amplifiers, there are two (one for X and one for Y), then to the scanners. The other signals go to the laser drivers then to the lasers. In my system, I use two power supplys, 1 for the scanner amps, and one for the laser drivers.

    Let me know if you have any more questions.

    Lazerjock

  8. #8
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    Default Re: Newbie blanking question

    that's perfect. makes complete sense. im going to open up the projector i have and take a look at whats in there and see if i can identify each part. my next step (as i slowly get the funds) is to start purchasing the parts needed to build the projector. ill definitely have more questions when it comes time to start putting things together. i am familiar with automotive electronics but ive never had to worry about esd before so im a little hesitant to start connecting things right away. but ill save all that for another time seeing as how it will be a bit before i have what i need to get started. but for now you've answered all of my questions perfectly! thanks again, ill be in touch.


    Luke

  9. #9
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    Default Re: Newbie blanking question

    actually i do have one more question. i have an interface box that came with the iShow software i have (or maybe the software came with the interface box, lol) so im assuming that is the DAC? will that DAC be compatible with any software and/or lasers i want to use? it has the standard DB25 connector so im assuming yes. i hate the iShow and plan on getting something better as soon as i can and id rather not have to buy (or make) another DAC just because i change software.

  10. #10
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    Default Re: Newbie blanking question

    sorry, i just thought of another question, lol. i was previously considering modifying the projector i have before attempting a complete buld from the ground up. i figured it would be easier and allow me to get my feet wet without jumping in head first. the first thing i wanted to do was trash the stepper motors that are in it. my question is would i need to replace the motor amplifiers/drivers or would the signal still be the same and all i need to replace is the motors themselves? after reading what i have so far im thinking it would all need to be replaced but i dont know for sure.

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