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Thread: IREEDZ, First Projector Build, Questions Galore

  1. #11
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    Stuka,

    Thanks for the Pangolin link. I see that a couple of my questions were answered there.

    Ian

  2. #12
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    Hi Ian!

    Glad to see you're starting your projector build. I'll do my best to answer your questions below.
    Quote Originally Posted by ireedz View Post
    The first question I have pertains to power supplies. Is it best to keep some power supplies devoted to only one job or can I utilize the same power supply for multiple things?
    There are two schools of thought on this. One is to have separate power supplies, as this way if one fails the show can continue with only one color missing. Personally, I'd rather buy a robust power supply that can run everything (and then some) for simplicity, and lots of other people have gone this route. It's really up to you, but in my opinion if you buy a decent PSU to start with (and chuck the cheesy one's that came with your lasers), you're OK with using a single unit to power all the lasers. (I still have a separate PSU for the scanners though.)
    Does anyone have experience with replacing the scanner power supply on dt-40 wides for something that puts out more amperage?
    allelectronics.com frequently has deals on 24 volt PSU's. You might check Digikey and Mouser too...

    In one of my earlier versions of my current graphics projector, I had a pair of 24 volt power supplies rigged in parallel to give me a split-rail PSU to drive the scanners. Each one was rated for 5.6 amps, which was much more than the scanners needed. Sadly, one of the PSU's failed anyway due to a short in the output wiring, so I went back to the stock PSU, and it's been fine ever since.
    I'm going to be running a manual shutter that is switched from the Remote E-Stop. Should I have a relay to switch the power in the projector?
    Yes. In fact, if you use the circuit I posted, you can run everything off that main relay. The shutter signal and the DC power to all the lasers all goes through the main relay, so when you have an interlock condition, not only do all the lasers turn off but the shutter closes as well.
    If so, what do you recomend and do you have a link for a supplier? I'm using the same actuators that are in flecom's projector here. They are out of the EKG's.
    Same suppliers as above (allelectronics.com, digikey.com, and mauser.com for starters.) DZ had a schematic that would drive the MFE actuators that Frank had, but really any 5 volt source will work.
    Also, I'm looking at buffo's schematic for the interlock and it calls for a 330 Ohm resistor, what resistor specifically should this be? I'm not sure how much power is flowing through that interlock circuit.
    A half-watt resistor is fine. The only current flowing in that circuit is the base-emitter current on the transistor. The 330 ohm resistor is there to limit that current to a safe value in case someone decided to use some huge honkin' NPN power transistor that had a potentially large base-emitter max current. (If you stick with a TO-220 package, you're probably fine no matter which transistor you select.)
    Also what is the consensus on voltage for the interlock circuit if any?
    No consensus. Some use 5 volts, some (like me) use 12 volts, and others use 24 V or more. Whatever you want to use is probably fine, but *DON'T* use A/C!

    Adam

  3. #13
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    Adam,

    Thanks for all the information. I'm going to be owing you a few cold beers, when all is said and done with this build. I will have plenty of additional questions once more components start rolling in from numerous sourced around the globe.

    I will be posting some pictures when things start to come together.

    Cheers, Ian

  4. #14
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    Nah, you don't owe me anything pal... The payoff will be seeing your rig running at SELEM 2011!

    Keep us posted on your progress Ian!

    Adam

  5. #15
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    In one of my earlier versions of my current graphics projector, I had a pair of 24 volt power supplies rigged in parallel to give me a split-rail PSU to drive the scanners. Each one was rated for 5.6 amps, which was much more than the scanners needed. Sadly, one of the PSU's failed anyway due to a short in the output wiring, so I went back to the stock PSU, and it's been fine ever since.
    I think this is the way I am going. I just want to make sure that I do this correctly, so I'm looking for someone to elaborate on the setup. I don't understand how I would run these parallel and get the +/-24V legs. It seems they must be in series to get the +/-24V outputs and the link joining the + on the first supply and the - on the second supply would be the zero Volt leg. Am I wrong here?

    Here is a photo of the supplies I'm looking to use.
    Click image for larger version. 

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  6. #16
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    That's correct, as Edison said; the + to - link wire becomes the common zero v leaving you with +24v zero v and -24v
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  7. #17
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    Quote Originally Posted by ireedz View Post
    I think this is the way I am going. I just want to make sure that I do this correctly, so I'm looking for someone to elaborate on the setup. I don't understand how I would run these parallel and get the +/-24V legs. It seems they must be in series to get the +/-24V outputs and the link joining the + on the first supply and the - on the second supply would be the zero Volt leg. Am I wrong here?
    You are absolutely correct. The "joining link" is your zero volt (that is, ground) reference. This will also need to be connected to your ILDA ground (pin 25).

    Do one test first though, before you connect these power supplies together in series:

    With everything off and disconnected, check the resistance between the DC output terminals and the FG terminal. You should have infinite resistance. Now test between each DC output and the metal case of the power supply. Again, you should have infinite resistance.

    If so, then you're golden. Just connect the + output of one supply to the - output of the other, and that "joining link" becomes your new ground point. One supply will be +24 volts, and the other will be -24 volts. And you're off to the races!

    Edit: Oops! Just noticed Doc's reply above. Yeah, what *he* said!

    Adam

  8. #18
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    Quote Originally Posted by buffo View Post
    You are absolutely correct. The "joining link" is your zero volt (that is, ground) reference. This will also need to be connected to your ILDA ground (pin 25).

    Do one test first though, before you connect these power supplies together in series:

    With everything off and disconnected, check the resistance between the DC output terminals and the FG terminal. You should have infinite resistance. Now test between each DC output and the metal case of the power supply. Again, you should have infinite resistance.

    If so, then you're golden. Just connect the + output of one supply to the - output of the other, and that "joining link" becomes your new ground point. One supply will be +24 volts, and the other will be -24 volts. And you're off to the races!

    Edit: Oops! Just noticed Doc's reply above. Yeah, what *he* said!

    Adam

    Checked supplies and everything checks out as correctly.

    I have an additional question for you Adam.

    I'm wanting to be able to connect multiple projectors to one estop. All projectors will be connected via Stanwax ILDA interface boards. Each of those boards has a 9 pin connector that handles all interlock wiring.

    What I want to do is to have a junction box that all the projectors will connect to. My idea is to have a power supply in this junction box that houses a double pole double throw relay for each projectors interlock circuit. I have a bunch of these relays, so I want to utilize them.

    The estop would control all of these relays. Is this feasible? I have not designed it fully yet, but I'm thinking this is the cleanest design for me since I'm using RIYA Dacs.

    Look forward to hearing your input.

    Cheers, Ian

  9. #19
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    There would be no need for the relays as the interlock circuit runs on transitor logic (a few mA), simply parallel connect the interlock connections in your junction box.
    http://img62.imageshack.us/img62/3985/laser.gif

    Doc's website

    The Health and Safety Act 1971

    Recklessly interfering with Darwin’s natural selection process, thereby extending the life cycle of dim-witted ignorami; thus perpetuating and magnifying the danger to us all, by enabling them to breed and walk amongst us, our children and loved ones.





  10. #20
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    Quote Originally Posted by Doc View Post
    There would be no need for the relays as the interlock circuit runs on transitor logic (a few mA), simply parallel connect the interlock connections in your junction box.
    Doc,

    My thought here is that I would want to isolate each projector.

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