something different from galvo scanners?

[lightlinked]

arduino, surplus uni polar stepper motor, 2n7008 mosfets, a lil copy and paste of code from the example sketches.

first surface mirror can be had for free from something you take apart in our modern world.

[norty303]

Servos would do it, if they're accurate enough and with enough resolution.

[planters]

Zorn,
Rather than going around about who said what (and who didn't), there have been a number of suggestions as to what you might do, but your EXACT application remains elusive. I would imagine if you wanted the problem solved and said to a number of the members "here's a commission, solve it" that there might be half a dozen solutions that would work.

I suggest you describe your application completely. Give the beam diameter, power, wavelength and divergence. Is it CW or pulsed? How many beams are there and how are they spaced from the source? What angle do they need to be moved through, what speed is needed in degrees/second or M/sec or kpps etc and what precision is needed? What is your time frame? What is your budget and do you have a future plan that would benefit from any of these capabilities being upgradeable?

If we know as much as possible about the application you will get the best suggestions.

[buffo]

If my reasons are wrong, tell me that instead of attacking me.

OK, at the risk of feeding a troll, I'll take your statement at face value and try to explain this rationally.

Every time we bring up an objection to your solution, you move the goal post. That is classic troll behavior.

Now, it may be unintentional on your part, and if so, then I apologize for labeling you as a troll. I admit it could be a language barrier at work. But this is not the first time it's happened, and I am not the first one to notice (or to complain about it).

Example: You said you did a simple Google search for "servo driver" and came up with all kinds of ideas for using the Arduino to drive a servo. But absent any further information, you are in no better shape than before the search, since those articles won't give you all the specifics you need to make an Arduino-based solution work. (If you've never worked with an Arduino before, it's going to take you quite some time to get familiar with it - especially if you've never done any coding before.)

However, I feel certain that as soon as I (or someone else) points this out to you, you will come back with further clarification, such as "Oh, I've been programming the Arduino for years", or "I have a friend who can do that for me" or some other new bit of information that changes the requirements (and the available resources) of the project.

That's moving the goal posts, and it pisses people off.

Define your need, give us an overview of your abilities, list what you don't understand, and detail any specific restrictions (cost, time, effort, etc) up front, not in the middle of a thread. And when someone offers advice (especially when they go to great lengths to give multiple options and provide pricing and availability information, and even links to specs, as Steve did), understand that it's considered rude to dismiss such advice out of hand without taking a hard look first. (Note: I said a hard look, not a cursory glance.)

Another example: it's taken you this long just to post a detailed description of the effect you want to create. And I'll also note right now that the effect you posted above does not require X and Y movement. It's single-axis only. Yet up until this point we've all been talking about dual-axis systems. Do we even need 2-axis movement? (If not, then this would vastly simplify the project!)

True, you said the effect you posted was just to show the speed, but we've already established that the speed isn't an issue for any of the solutions we've been discussing. Thus most rational people would take your example and run with it. Now, if someone were to spend time working up a cheap solution for single-axis-only movement, and you then throw that solution out because what you really want is dual axis movement, then you've just wasted that person's time. That causes friction. Get it?

Stage lights seem to be using them instead of galvos and servos. I'd like to discuss stuff like that

Some stage lights do indeed use servos. And if you can find a broken fixture on E-bay that has working servos in it (something like this, only hopefully cheaper if the lamp is dead) then you can control it using DMX. (Do you have a DMX board? Or an Entec USB-to-DMX adapter? Or some other way to control a DMX device? We don't know...) And as I alluded to earlier, if you plan to build a whole bunch of these things, you might even be able to purchase brand-new modules in bulk off-the-shelf - which might bring the price down to something more affordable.

But to build such a unit from scratch is going to either require purchasing an off-the-shelf DMX servo controller or building one up from something like an Arduino. Then you need servos. (What kind? How much torque? What voltage to run? Etc...) Then you need a mount. And all of this will need to be hand-assembled and tested, by you.

Up until this point you have not indicated a strong desire or aptitude to do any of this. If this characterization is incorrect, then you need to re-state the problem and your available resources (including your own abilities) more clearly.

In the end, since you are (presumably) already familiar with laser show software and laser show controllers, but have not yet mentioned any ability when it comes to working with an Arduino, it appears to most of us that a galvo-based solution is the easier road to take, even if it might be slightly more expensive. (Note that my $200 quote above included the cost of a correction amplifier, which really isn't needed in this application, so you can cut that cost in half.)

But as I said earlier, if you want to embark on a journey of discovery re: servos, DMX, and the Arduino - by all means have at it. No one is preventing you from doing what you want. I don't think you will save much money vs a galvo solution, and I believe you *will* spend a lot more time on it, but admittedly you will probably learn something in the process. And sometimes learning is more fun that actually completing the project.

I'd like to discuss this with lightlinked, logsquared, VDX and others.

While you're at it, be sure to discuss it with Dream, Cypher0, and Magnus as well. I'm sure they can offer additional assistance.

Adam

[lightlinked]

okie. i have some rc stuff and a hot glue gun, along with some mirrors out of a broken lcd projector.

let me say, i was skeptical at first. then once i tried out one servo, the cheapest hobby king analog servo, it worked better than i expected. so i glued another mirror to this camera mount i made a while back, which uses a nicer hitec analog servo, and wow. such amusement.

for $20-$40 and a trip to the local hobby shop, you could play with this today too and see for yourself if its worth it.



now there are fast servos and accurate servos out there. these r pretty cheap. some of the metal gear ones are actually pretty nice inside

[buffo]

Based on your pictures, I'm assuming you used that RC transmitter/receiver shown in the second picture to run the servos, yes?

Adam

[buffo]

If the motion of these is precise enough I dont see why I'll need anything else.

Except some way to control the servos...

Unless you want to use an RC transmitter, that is. (And admittedly, this would work, assuming you don't mind using the joystick to move the beam around.)

But you would need a different radio for each set of servos, unless you build a buffer board to daisy-chain the output of the receiver to multiple servos and you don't mind that they all move the same way.

And again, the reason there are so many assumptions here is because you still haven't explained the full requirements of the project. (You said "if it's precise enough". How much is "enough"?)

Try to answer these questions:

Do you need X and Y movement?
How wide is "wide enough"? 60 degrees OK? 90 degrees? 120 degrees? (It matters!)
How many units total?
Does each unit need to be individually controllable, or can they all do the same thing?
Is all-analog control (someone moving a knob or joystick) OK, or does it need to be programmable (operates stand-alone) and/or music-synchronized?
How accurate does the positioning need to be? (is there a risk of audience exposure if the position drifts by 1 degree? What about 5 degrees?)
Are you willing to learn to program a micro-controller to make it work if need be?
Are you comfortable soldering electronic components to build a board from scratch if need be?

That will make it easier for someone, anyone, to help.

Adam

[lightlinked]

you can control the servos with a computer or microcontroller. there is also some readily available software for animatronic applications.
you could also use something real hipster like a macbook running max msp to an arduino then to that pwm board. artist statement in helvetica, free wine and cheese while you chat about the postmodern condition

if you have access to a 3d printer, you can make the mount pretty slick, or just use some angle aluminum.

or you could rent a grand ma2 and 8 of those dmx mirrors because the grant money is making it rain, which could also be part of the install in gallery 2 with the interpretive dance.

please dont blast class IV laser with hobby servos if it can hit people

[buffo]

please dont blast class IV laser with hobby servos if it can hit people

Honestly, I wouldn't trust open-loop scanners with that either. (Well, not unless you had a hard mask that would protect the audience, that is.)

Adam

[mixedgas]

Guys, FYI, Cyper0, Dream, Magus and Zorn are the same person. I'm the one who figured that out. He thought that he could hide his identity and manipulate threads, in his words: "Russian Style". What he didn't hide is a critical fault in human nature, especially when there is a clock in the lower right corner of my screen. It becomes easy to time stamp what and when he posted in the past. I could even follow him across forums by that method alone.

No, I'm not leaving the thread. I wasn't going to bring up the past, because you appeared to be behaving yourself and were politely using just one name...

Servos for laser and lighting systems are pretty bad unless you have good digital servos, using the digital control mode, not the PWM, and metal geared servos. Servo repeatability is poor, compared to galvos. The beams shake when the motion stops. When you tear into a mid cost fixture that uses servos, you usually find a slotted optocoupler helping to set the home point for the servo.

Low Cost Servos do not live very long in continuous motion, a few hundred hours at best, and its not the gears that fail, its the feedback potentiometer. Besides, for speed and positioning accuracy, you want the digital mode servos, not the slightly cheaper PWM servos.

Intelligent lighting fixtures using servos usually are sold by manufacturers who enjoy profiting from selling replacement parts.

What your asking for is right up the G330DT's alley, and at any given time, I can find 2 to 10 of them on Ebay. Considering they almost never wear out the bearings in normal use, they are ideal for big mirrors, which is what they were designed for, 25 years ago. Yet they are still in production. They will be faster and smoother then a servo, even with the open loop "G330" version.

If there was something other then a DC or brushless geared motor with feedback, a stepper, or a galvo for this task, believe me I would know. I've only been searching for 25 years....

And if you use servos, you probably want a Servo player-recorder... Such as https://www.servocity.com/html/servo...ck_contro.html Some of them are programmable with SD card or controlled with USB.

Steve