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MisterWilling
04-24-2010, 16:21
Hello fellow laser lovers,

I just started putting together my first scanner build and I have a few questions to start with and I will have many more as I progress in my build. I am a CNC programmer so building the parts is easy for me but I have no electrical experience except for building my own laser modules.

Right now I'm working on the wiring aspect. I'm trying to follow what this guy is doing as his setup looks very professional. http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help!-My-first-RGB-projector-project-(expecting-approx.-2W-system)?p=140261#post140261 (http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help%21-My-first-RGB-projector-project-%28expecting-approx.-2W-system%29?p=140261#post140261) Although his setup is more complex and I don't understand the interlock circuits. I can just barely comprehend a wiring diagram so this is all new to me.

I have these power supplys: 5v, 12v, 5v ( for LW 532), 5v (for LW 473), and the +/- 24 for my ScanPro 40's. So I should tie all the AC Line's together at a single point and have a fuse connected to them coming into the projector. Then I would do that same with the AC Neutral except no fuse is needed. The AC Ground should then all be tied together and grounded to my baseplate.
After I do all that I would need to make sure my lasers are isolated from the baseplate correct? Do the laserwave modules need any additional isolation or do the come isolated all ready? All my homebuilt modules are all ready isolated except for my 650nm which I can isolate by having the baseplate anodized.
Now for the DC: I would simply connect the + to + for each corespnding component and then the - I would tie them all together and connect them to ILDA pin 25? What goes on pin 25? I am using a soundcard DAC so would I have to connect anything to it when I wiring up the DAC to the ILDA cable output?

Is there anyone in the US who wants to build me an interlock circuit? I could pay you for it of course I just keep scratching my head when I look at the diagrams. I am going to try and build this thing with all the saftey features: Beam shutter ( I have a GM20 and shutter driver from DZ), key switch(I have one) , emission indicator LED when I get the interlock thing figured out, the delay turn on will have to be added later since my lasers are homebuilt and dont have it.

Heres some pics of my mock setup. I will get everything polished and anodized after I get it all figure out. The top plate sits above the baseplate with some angles on each corner. The lasers are: 532@500mW , 473@250mW , 405@600mW , 650@450mW , and 642@300mW . I have all the optics and mounts to get this done.

Thanks,
Austin

buffo
04-25-2010, 05:47
I don't understand the interlock circuits. I can just barely comprehend a wiring diagram so this is all new to me.
Hello Austin;

The interlock circuit in that thread is my design, and it's just one way to do things. You don't need to follow my design if you don't want to. I admit that my circuit is difficult to follow if you don't have a background in electronics. (If you're looking for a good primer on basic electronics, I suggest you pick up a copy of Forrest Mimms' (http://forrestmims.com/) excellent book, "Getting Started in Electronics (http://www.amazon.com/Getting-Started-Electronics-Forrest-Mims/dp/0945053282)". That's how I taught myself!)

The important features of the interlock circuit are as follows:

1) it must be able to quickly shut down the lasers and close the shutter when activated
2) the operator must be able to activate it manually (and remotely)
3) once activated, it must remain in a "safe" (or shutdown) condition until the operator commands it to re-start

The things that should trigger a shutdown are:

1) loss of A/C power to the projector
2) pressing the remote kill switch
3) turning the keyswitch off
4) unplugging the ILDA cable
5) opening one of the panels on the projector (this one is optional, but highly recommended, even though it is not shown in my schematic)

How you design the interlock circuit to accomplish these goals is up to you, but a common method is to use a multi-pole relay as a sort of "master switch". This relay, when energized, will send DC power to the laser drivers, and it will also connect the shutter signal from the ILDA cable to the input for the shutter driver, allowing the software to open the shutter. Thus, if the relay is open, you have an interlock condition, and if it's closed the projector is running.

Typically the power that flows through the relay's coil (the electromagnet that holds the relay closed) is also routed through the closed contacts of the relay. Thus, if the relay ever opens, this creates a permanent open circuit so that the relay can't re-close. To re-start the system, a momentary switch is wired around the open contact to apply power to the coil to pull it closed. This is the "run" or "re-start" button. Once the relay closes, the power flows through the closed contact to keep it energized.

Note that all the interlocks are wired in series. That is, you design the interlock switches so that they interrupt the flow of current in the loop when an interlock condition happens. This is why you see people talking about pins 4 and 17 on the ILDA cable. The projector sends current down the cable, and since the two pins are connected inside the controller by a piece of wire, the current comes back to the projector and continues through the interlock circuit whenever the cable is connected. If you yank the ILDA cable, the circuit is interrupted and the main relay opens, triggering the shutdown.

I have these power supplys: 5v, 12v, 5v ( for LW 532), 5v (for LW 473), and the +/- 24 for my ScanPro 40's. So I should tie all the AC Line's together at a single point and have a fuse connected to them coming into the projector. Then I would do that same with the AC Neutral except no fuse is needed. The AC Ground should then all be tied together and grounded to my baseplate.Yes, though you may want to put a main AC power switch in this circuit as well. Also, many people install a single 5 volt power supply rather than having multiple PSU's inside the projector. But if you do this, be sure the one power supply can supply enough current for all the lasers. (Note that the more power supplies you have, the more poles on the main relay you'll need.) You *can* use the main relay to switch the incoming A/C power instead, but this might delay the shutdown of the lasers, since some power supplies continue to produce DC power for a second or two after they are disconnected from the A/C line.

After I do all that I would need to make sure my lasers are isolated from the baseplate correct?It would be best, but it's probably not required. The diodes should already be isolated from the case inside the head. The danger here is that 1) if you're using a low side driver, then grounding the diode will blow it from over current, and 2) if you connect the A/C and D/C grounds you create a large ground loop between the projector's A/C power source and the computer with the controller. Since the diode is already isolated, you shouldn't have to worry about #1. And in practice the ground loop (#2) might not matter. In some cases it could cause noise on the signals to the lasers and scanners, but I've personally never had a problem with it. (Still, others have reported problems.)

Now for the DC: I would simply connect the + to + for each corespnding component and then the - I would tie them all together and connect them to ILDA pin 25? What goes on pin 25?Red+, Green +, and Blue + each go to the positive modulation inputs on your laser drivers. The negative modulation inputs get connected to pin 25, which is ILDA ground. Also, the grounds from all your DC power supplies get connected to ILDA pin 25. The X + and X - signals go to the inputs on the X scanner amp. (Same thing for Y.) Do *not* connect ILDA pin 25 to the signal ground pin on the scanner amp input.

I am using a soundcard DAC so would I have to connect anything to it when I wiring up the DAC to the ILDA cable output?You need a correction amp on the output of the sound card... Beyond that the connections should be straightforward. The DC negative (ground) on the sound card connects to ILDA pin 25. Remember that pins 4 and 17 need to be connected at the sound card end. (There aren't any signals placed on these pins by the controller. It's just a loop so the projector knows that the cable loop is complete.)

Is there anyone in the US who wants to build me an interlock circuit?Fill out your profile so we know where in the US you are located. You might discover that there is someone near to you that would be willing to meet with you and help you with your projector. *retardo

If that doesn't work, I could send you the parts and a point-to-point diagram for you to follow...

the delay turn on will have to be added later since my lasers are homebuilt and dont have it.This is easy to implement. All you need is one of these (http://www.elkproducts.com/products/elk-960.htm). It has a built-in, adjustable delay. When the main relay closes, it actuates this relay. After the time delay, this one closes to send power to the lasers. Easy as pie! (And they only cost around 20 bucks.)

The lasers are: 532@500mW , 473@250mW , 405@600mW , 650@450mW , and 642@300mW . I have all the optics and mounts to get this done.How are you planning to mix the 650 nm red with the 642 nm red? That's a band of only 8 nm between them. I've never seen a dichro that could handle that. If you've got one, I'm very curious as to where you found it and how much you paid for it. Have you actually tested this on the bench to be sure it works?

Adam

MisterWilling
04-26-2010, 08:33
Thanks for long and detailed explanation. Its starting to make sense now.

Yes I was planning on having a main switch for the AC power.



Fill out your profile so we know where in the US you are located. You might discover that there is someone near to you that would be willing to meet with you and help you with your projector. *retardo

If that doesn't work, I could send you the parts and a point-to-point diagram for you to follow...

I would gladly take you up on your offer of the parts and a point to point diagram. How soon do you think you get get one going for me and how much would it cost? BTW I do have a case interlock switch I got from DZ laser that I am going to use if that makes a difference in designing my circuit. I also am going to use a breakoutboard from DZ if that makes a difference.



How are you planning to mix the 650 nm red with the 642 nm red? That's a band of only 8 nm between them. I've never seen a dichro that could handle that. If you've got one, I'm very curious as to where you found it and how much you paid for it. Have you actually tested this on the bench to be sure it works?

The 650 is polarized one way(beams stacked on top, its also probably 658nm) and the 640 is polarized the other way (beams side by side) and I will use a PBS to combine those beams. The other lasers are combined with LaserWave dichros and a semrock dichro for the blu-ray.



Red+, Green +, and Blue + each go to the positive modulation inputs on your laser drivers. The negative modulation inputs get connected to pin 25, which is ILDA ground. Also, the grounds from all your DC power supplies get connected to ILDA pin 25. The X + and X - signals go to the inputs on the X scanner amp. (Same thing for Y.) Do *not* connect ILDA pin 25 to the signal ground pin on the scanner amp input.

So I would connect the +5V From the Power supplies to the + input on the drivers for the lasers. The 5v- would go to common ground and ILDA pin 25. Then the Mod+ signal line to the corresponding ILDA pin and the Mod- together and to ILDA Pin 25? In this diagram http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help!-My-first-RGB-projector-project-(expecting-approx.-2W-system)?p=140261#post140261 (http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help%21-My-first-RGB-projector-project-%28expecting-approx.-2W-system%29?p=140261#post140261) the mod+ and mod- are not connected that way... Am I missing something?

buffo
04-27-2010, 10:30
I would gladly take you up on your offer of the parts and a point to point diagram. How soon do you think you get get one going for me and how much would it cost?
It might take a while, as I'm quite busy, but I won't charge you anything over the cost of the parts and the postage. Send me a PM of everything you have so far and I'll get started on it this weekend.

BTW I do have a case interlock switch I got from DZ laser that I am going to use if that makes a difference in designing my circuit. I also am going to use a breakoutboard from DZ if that makes a difference.The breakout board makes wiring easier. As for the interlock switch, I'll need to get with DZ to see exactly what he sold you. I wasn't aware that he had anything like this. If it's simply a normally-closed switch that opens when you remove the case panel, then that's no problem to add to the circuit.

The 650 is polarized one way(beams stacked on top, its also probably 658nm) and the 640 is polarized the other way (beams side by side) and I will use a PBS to combine those beams. Ahhh... From the power levels you mentioned, I figured there were two diodes in each laser, but I didn't consider the possibility that they were knife-edged together to make a single beam. Instead, I assumed they were already combined with a PBS cube internally.

OK, in that case your plan should work just fine. Your resulting beam might be a tad large, but you won't have any problems with the PBS cube.:)

So I would connect the +5V From the Power supplies to the + input on the drivers for the lasers. The 5v- would go to common ground and ILDA pin 25.Yes, the +5 volt supply from the AC-to-DC power supply gets connected to the + power input on the driver. Note, however that the negative side of the DC power supply is *NOT* -5 volts. Rather, this is zero volts, or ground. And yes, it gets connected to the ground input on the driver as well as the DC common ground in the projector (which is also Pin 25 on the ILDA cable).

Then the Mod+ signal line to the corresponding ILDA pin and the Mod- together and to ILDA Pin 25? You have a choice on the Mod- signal. You can connect each one to the individual mod- input for each driver and stop there, or you can connect them all together (both the mod- inputs and the mod- signals) and then connect all that to ILDA pin 25, which is ground.

Either way will work. The difference of opinion comes from the fact that almost no laser drivers actually support differential signaling for color modulation. So, if they're all single-ended, then the negative input is actually at ground potential already. And in fact, many controllers connect the negative color signal pins to pin 25 internally. Thus, some people choose to wire it as a single-ended input, which means that the mod- signal is grounded.

But there's nothing wrong with wiring it differentially (which would have the negative signals connected to the negative modulation inputs on each driver - separately) if you want. Indeed, this is the "correct" way as defined in the ILDA standard projector specification, even though very few (if any) lasers or controllers actually use differential signaling for color modulation.

In this diagram http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help!-My-first-RGB-projector-project-(expecting-approx.-2W-system)?p=140261#post140261 (http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help%21-My-first-RGB-projector-project-%28expecting-approx.-2W-system%29?p=140261#post140261) the mod+ and mod- are not connected that way... Correct. In his diagram, he has the color signals connected differentially, as explained above. This is another accepted method, and it will work. (Even though the signals themselves are not differential, nor is the receiver on the laser driver module a differential receiver.)

Adam

MisterWilling
04-27-2010, 14:25
Thanks for the further explanation of wiring. I think I am wrapping my head around it more.

Next I'll have to ask about how to wire up my DMX boards but I'm going to try and figure out as much as I can and ask specific questions when i get a chance.

I'm sending you a PM about what parts I need incorporated in my interlock circuit.

Austin

MisterWilling
04-30-2010, 11:16
Okay Adam helped me work out quite a few things, now it on to my next question...

I have a couple of DMX program boards that Dave from LSP supplied me with, how would I go about wiring those in? I might just do one board but I'm going to hook them both up to see how I like them before I decide.

Would I just wire the boards in and add switch to turn them off or on depending on if I'm using DMX or ILDA input?

taggalucci
05-01-2010, 20:12
I'm trying to follow what this guy is doing as his setup looks very professional. http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help!-My-first-RGB-projector-project-(expecting-approx.-2W-system)?p=140261#post140261 (http://www.photonlexicon.com/forums/showthread.php/10314-Need-some-help%21-My-first-RGB-projector-project-%28expecting-approx.-2W-system%29?p=140261#post140261) Although his setup is more complex and I don't understand the interlock circuits.

Glad to hear my thread has been helpful :) As for "professional", I'm not sure, but thanks for the praise! My intent behind documenting the build from start to finish was to capture all of the information I gathered, to complete the build, as a resource for others to use.

I would suggest that your project, with the multiple wavelengths (i.e. more than 3), would most likely be just as (if not more) complex. It is because I am considering adding 405nm to my projector that I came across your thread in a search. So I will be following your thread keenly to hear of your experiences with this in terms of the colour mixing. So please add any observations you make regarding this.

What laser(s) are you using for your 405nm?

Good luck :)

MisterWilling
05-02-2010, 09:21
The 405 has been one of the biggest troubles of the project. I am using two 12x blu-Ray burner diodes from pioneer bdr-205 drives. I have the diodes at 300mw Each using aixiz 405 coated lenses. They have three elements so the loss is 20% but they have good round beams. The diodes are in parallel with a 4 ohm balancing resistor powered by flexmods for analog modulation. I am combining the two diodes with a PBS. I am adding the 405 in using a semrock dichro because it have almost neglagable losses and all
my lasers pass through the 405 dichro. It was 200 dollars but it was worth it for the
amount of power I would have lost through a cheaper dichro. When adding 405 you also have to check the losses through you scanner mirrors, my stock scan pro 40 Morris have a losses of 20% v polarization and 35% h polarization. I tried aluminaized mirrors and they were about the same but they are lossy on all wavelengths, and newer style scanpro40 mirror ( the ones with angled cuts on all four corners ) were at almost 70% loss on v pol.

All that trouble aside, I should get 400-450 mW after optics for around... 400- diodes , 35 for driver, 40 for lenses , 200 for dichro , 40 for pbs. So just over 700usd , I'm just trying to balance out the colors without buying a 600mW 473 (which I can't affordO_o).

buffo
05-03-2010, 07:43
I'm just trying to balance out the colors without buying a 600mW 473 (which I can't affordO_o.

Not to worry! Most of us are in the same boat. Very few people can afford 600 mw of 473 nm blue! :o

Adam

MisterWilling
05-14-2010, 15:39
When mounting the galvo's in my mounting block, one of the galvo was angled down in such way that the connector hit my base plate. I found it easier to flip the scanner mirror over in the galvo so that the connector was angled up after it was mounted. That way I didnt have to pocket out my base plate. Is this going to affect my output, like invert it?