Right... What DZ said! :D
Also, all this is in the first part of the tutorial.
Adam
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Right... What DZ said! :D
Also, all this is in the first part of the tutorial.
Adam
Just ordered one, thanks Dave
Received, it looks nice. I have read the tutorial, however I'd lke to get past generalities.. before I use this I'd like some hard specs on the capabilities of board. Something like a data sheet.
A good start would be:
Min/max: Vin, Vout, Gain, Offset, and Min/Max timing shift of RE, FE.
Absolute Maximum ratings for Vin, Iout.
Output impedance and recommended current driving capability.
Input impedance.
Output saturation voltage verses supply voltage (although I can guess this from the TL084 chips datasheet)
Please excuse me if this is an unusual request but my engineering side would like to know what it's dealing with before installing and trying to use this component in my projector.
Thanks!
You understand we're talking about the color modulation signal, right? So a data sheet with gain and output current limits is really pointless. The range of voltages is zero to 5 volts. Period. The outputs of the board are hard-limited to that range regardless of any adjustments on the board or any faulty input signals you send to it. DZ mentioned all that in his earlier posts about the board.Quote:
Originally Posted by drlava
As for current driving capability, why are you even concerned about that? This is COLOR MODULATION data. It's not designed to drive anything. Your input stage on the laser driver should be a very high input impedance device - something like a mosfet - so the board shouldn't be sourcing much current at all. (As an analogy, would you request a data sheet for the Easylase USB controller before you connected it to your projector, so that you would know how much current it could source on the modulation lines?) For the record, even a QM-2000 can only source around 20 ma or so on the color lines.
Also, it's been demonstrated that the board can drive a pair of drivers on a single color channel with no problems. Laser drivers typically don't pull more than a few ma of current, so unless you want to drive 30 drivers off a single channel, I don't see where the problem lies.
You might want to send DZ a PM. He may be willing to share more details about the board with you. Though really, if you are uncomfortable installing it in your projector, then connect it to a dual-trace oscilloscope first and watch the input and output traces as it's operating. That should quell any concerns you might have.Quote:
my engineering side would like to know what it's dealing with before installing and trying to use this component in my projector.
Adam
Hmm I hope you're joking.. :)Quote:
Originally Posted by buffo
You might not be used to working with components and using data sheets for design, but these are the sort of things that would commonly be specified for any component, and this is a projector component. Whether he mentioned it in earlier posts in other threads is irrelevant, a product should have a consolidated data sheet. It's understandable that he hasn't done it yet, this was just a friendly (hopefully helpful) push in that direction.Quote:
So a data sheet with gain and output current limits is really pointless. The range of voltages is zero to 5 volts. Period. The outputs of the board are hard-limited to that range regardless of any adjustments on the board or any faulty input signals you send to it. DZ mentioned all that in his earlier posts about the board.
Again, it's for specification purposes. Without knowing the rating, we're left to guess that, yeah it should work with a few lasers on each color, but given each laser has a different input impedance, it's speculation until the facts are in. If I paid around $300+ for an easylase controller, you better believe I would expect it to come with specifications such as this, and especially if I paid a few thousand for a pango board. Would you not? You see, the output impedance is an important measure. Let's say that I'm building a multi-red laser with 8 diodes and drivers. Let's say that each driver takes 1mA, you might think that a board that can source 20mA is fine, and it would be, at least it wouldn't be damaged, but if the output impedance after feedback is 100 ohms then instead of 5V modulation out you could get (5-0.001*8*100) = 4.2V ! That's a more extreme example of why specifications are important.Quote:
As for current driving capability, why are you even concerned about that? This is COLOR MODULATION data. It's not designed to drive anything. Your input stage on the laser driver should be a very high input impedance device - something like a mosfet - so the board shouldn't be sourcing much current at all. (As an analogy, would you request a data sheet for the Easylase USB controller before you connected it to your projector, so that you would know how much current it could source on the modulation lines?) For the record, even a QM-2000 can only source around 20 ma or so on the color lines.
Additionally, the range of delays has a direct impact on whether the board fits certain applications, so this is another natural spec.
There is no problem, it was a request.Quote:
Also, it's been demonstrated that the board can drive a pair of drivers on a single color channel with no problems. Laser drivers typically don't pull more than a few ma of current, so unless you want to drive 30 drivers off a single channel, I don't see where the problem lies.
You've seen my review of the S-KY blue laser so you should know that I prefer quantitative specs to qualitative specs (and reviews). Heck, most engineers do.
Sent a PM a long time ago, and we got off to a good start. This is less about sharing details and more about defining what he's selling. Sure, an oscilloscope is an option but typically one isn't left to figure out the specs for themselves when buying a component. If you go to my site you'll see every electronic component I sell has a spec sheet.Quote:
You might want to send DZ a PM. He may be willing to share more details about the board with you. Though really, if you are uncomfortable installing it in your projector, then connect it to a dual-trace oscilloscope first and watch the input and output traces as it's operating. That should quell any concerns you might have.
Adam
You see, while your tutorial is nice in a hand-holding sort of way and it's great you got it out there, but with a spec sheet I wouldn't need to read it all all, everything would be clear what to do, and it would be natural, like scanner tuning. Hope that clears up to you where I'm coming from!
Then you would be dissappointed, because it does not come with such a spec sheet that lists impedance for the color outputs.Quote:
Originally Posted by drlava
As for me, no, I would not be upset, because I understand that it's information that I do not need.
If I was building such a multi-red laser, I would contact the manufacturer and ask the question. But what you are talking about is the exception, not the norm.Quote:
Let's say that I'm building a multi-red laser with 8 diodes and drivers.
Such information would only be useful if you already had the delay information available for the lasers you want to use. But the only way you're going to get that sort of information is to perform the tests yourself with a fast photodiode. (Well, unless you pay serious money for a high-end laser made in the US, and even then you'll need to select one that was built to meet a certain spec in the first place.) Look at any of the Chinese lasers that people here on PL are using and see if you can glean any useful information about RE and FE response times from the specs that are provided.Quote:
Additionally, the range of delays has a direct impact on whether the board fits certain applications, so this is another natural spec.
DZ did mention in his early posts about the board that the delay circuit had two ranges (jumper-selectable), and I'm sure he can provide more information to you about specific delay times if you want. However, this product was designed to be as easy as possible for the hobbyist to install and adjust. Including the specs you are asking about would be irrelevent to the vast majority of the targeted users of the board.
Well, I see it more as needlessly complicating what is intended to be a simple solution. If you are hung up about specs, that's your prerogative, but they are meaningless to nearly everyone else. Heck, you can't even verify the response times unless you have a dual trace oscilloscope and a fast photo-diode, so what's the point in even talking about them? No one else is going to be able to use the information. In fact, the adjustment procedure was written specifically so that the board could be adjusted correctly *without* requiring any special test equipment.Quote:
This is less about sharing details and more about defining what he's selling.
Adam
I'm not sure why you are so insistent on arguing against quantitative documentation.. this is not even your product.
Just because you would not use it personally, why do you think it should not be available to others that could?Quote:
Originally Posted by buffo
Actually, you're wrong about this. The delay range only really needs to be as large as the slowest reasonable sample-to-sample time of your DAC, because then the color shift can be compensated by point shifts and the board takes care of the rest. So no information of the laser delay is needed, and besides that, there are test frames that can show you the delay of your laser, no special equipment is needed.Quote:
Such information would only be useful if you already had the delay information available for the lasers you want to use. But the only way you're going to get that sort of information is to perform the tests yourself with a fast photodiode. (Well, unless you pay serious money for a high-end laser made in the US, and even then you'll need to select one that was built to meet a certain spec in the first place.) Look at any of the Chinese lasers that people here on PL are using and see if you can glean any useful information about RE and FE response times from the specs that are provided.
More detail complicates use? Are you a single-button mouse man? :) All along we have been talking about a separate spec sheet from your tutorial which beginners wouldn't read anyway, so it wouldn't complicate anything. Again, I don't see why you are so insistent on saying that because you wouldn't use something, it shouldn't be available to others who could. In the end this is DZ's decision and I'm sure he's capable of making it himself.Quote:
DZ did mention in his early posts...
Well, I see it more as needlessly complicating...
Adam
I'm arguing over your hypocritical stance on the issue. You expect this product to come with a spec sheet that contains excessive documentation, yet you don't provide some of those same specs (like input & output impedance values) for your own Flexmod drivers, nor do you demand that the lasers you purchase come with simiilarly detailed modulation performance data. In short, you are trying to hold DZ's product to a much higher standard than your own. (Or any other laser related product on the market.) I find that offensive; it's as if you're trying to play a round of stump the teacher when you know darn well that the actual point you are arguing about is meaningless.Quote:
Originally Posted by drlava
My point is that it's highly irregular to include such information with such a trivial product. Even high-end laser show controllers do not include the information you are asking about, yet you don't seem to be complaining to the likes of Medialas, Pangolin, and Full Auto about it. So why all the attention on this color board all of the sudden? Particularly when DZ is producing it at such a low cost? As I said, if *you* want the information, then you can contact DZ privately for it, but there's no need to insist that he include it with the kit. (Honestly, why did you even buy the thing if you felt you needed all this extra information before you'd hook it up?)Quote:
Just because you would not use it personally, why do you think it should not be available to others that could?
Clearly, you haven't connected the board and experimented with it, or you would not have made such a general (and completely incorrect) statement. The board needs to be able to slow down the fastest laser to match the response time of the slowest laser. This has nothing to do with sample-to-sample time. (Hint: not everyone runs at 30K, remember. The sample-to-sample time is a completely separate variable that the board has no bearing on.)Quote:
The delay range only really needs to be as large as the slowest reasonable sample-to-sample time of your DAC,
However, you are correct in that you don't need an oscilloscope to set up the board, because you can see the results on the test patterns as you adjust it. But you completely missed the larger issue. You are asking for delay information about the board, even though it will do you no good unless you have matching delay information about all three of your lasers - and that information can only be measured with a fast photodiode and an oscilloscope.
Fine - you're an engineer. Send DZ a PM and ask him for the information. But don't make it sound like he should have included this laundry list of specs from the very start, when no one else in the industry (including you) does this, and when it will not change the setup or operation of the board one bit.
Adam
Hmm, it looks like what started off as "Please excuse me if this is an unusual request" has turned personal. Ouch! I'll try to stay away from that.
The datasheet I include with the flexdrive and flexmod has a LOT more detail on using the item and specs than any other similar hobbyist spec sheets I have seen (when they exist). Whenever anyone has asked a technical question about the use of my drivers, I've given the detail they asked for and more, and generally then include it in the sheet. FYI the output impedance of a current controlled driver is meaningless I.E. close to zero. If anyone had ever asked about the input impedance I would have answered fully, and now that you have asked I'll put it in. Do you see the difference? Not only is there a spec sheet but it includes a lot of details and will be added to per requests.. I don't see this as hypocritical.Quote:
Originally Posted by buffo
"Please excuse me if this is an unusual request" was my original statement. I'm not complaining, I asked because I bought it, I bought it because it's a useful and good product at a good price. You don't see me 'complaining' (asking?) about Medialas, Pangolin, and Full Auto because I have not purchased their items. Why the vitriol?Quote:
My point is that it's highly irregular to include such information with such a trivial product. Even high-end laser show controllers do not include the information you are asking about, yet you don't seem to be complaining to the likes of Medialas, Pangolin, and Full Auto about it. So why all the attention on this color board all of the sudden? Particularly when DZ is producing it at such a low cost? As I said, if *you* want the information, then you can contact DZ privately for it, but there's no need to insist that he include it with the kit. (Honestly, why did you even buy the thing if you felt you needed all this extra information before you'd hook it up?)
Like I said, I contacted DZ a long time ago and he answered the most important question directly so as far as I was concerned this discussion was mostly over before you entered.
What I was saying was that if the slowest laser is slower than the fastest laser by more than a whole sample time, then I can set the software to compensate for that laser up to less than the sample time and the board can take care of the rest. This is fact, and why I said that was the minimum required delay range. Again, maybe a different use from yours, but still correct but you claim it's incorrect because that's not the way you use it. Ideally, the board corrects for the whole range of laser delays, but I was stating a minimum value there.Quote:
Clearly, you haven't connected the board and experimented with it, or you would not have made such a general (and completely incorrect) statement. The board needs to be able to slow down the fastest laser to match the response time of the slowest laser. This has nothing to do with sample-to-sample time. (Hint: not everyone runs at 30K, remember. The sample-to-sample time is a completely separate variable that the board has no bearing on.)
not true, sorry. Maybe I'll draw up a delay measurement frame, should be fun. Also, the purpose of my drivers is to drive lasers, so I focus on that aspect in the sheets. A main purpose of the board is to delay, so... why not include delay info. Seems logical.Quote:
But you completely missed the larger issue. You are asking for delay information about the board, even though it will do you no good unless you have matching delay information about all three of your lasers - and that information can only be measured with a fast photodiode and an oscilloscope.
Already done. This information is very simple for the designer to specify. I do conscientiously include lots of specs for hobbyist type boards as stated previously, more than most. It helps the setup and operation of the board for those who know what to do with specs. Please take a look at this outside of your current perspective.Quote:
Fine - you're an engineer. Send DZ a PM and ask him for the information. But don't make it sound like he should have included this laundry list of specs from the very start, when no one else in the industry (including you) does this, and when it will not change the setup or operation of the board one bit.
Adam
YOU TWO ARE HEARBY ORDERED
TO BE FRIENDS!
Or I will lock you in a room at Selem with a repeating loop of the song "The Farmer and The Cowboy Should be Friends" From Oklahoma!
Steve