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856  Forum 2005-2010 (read only) / Interfacing / Re: Help with a project wireless LED control on: October 18, 2010, 06:57:02 am
Just a thought, before you go and get too complicated... maybe the right answer could be modifying the controls so that Tink could do it more easily, rather than remote control.  I'm just thinking along the lines of added complexity adds more places for things to go wrong.

As it is a play, there's a specific sequence that Tink's lights will follow- in other words, you might have four or five sequences needed for the character, for particular scenes.

That being the case, why not program those sequences in, and have her just press a single button for each sequence?  I'm just thinking that remote control adds a lot of places for problems, and the problem seems pretty easy to address.

As for how to hook it up, I'd probably use a power transistor.  The arduino provides PWM for us, all we need to add is a nice switching transistor that can handle the total current of those 50 LED's.  Four channels of PWM is still "stock" arduino language, so you won't even need to use an external library.

tink's still gonna need to be toting a couple of batteries, if those scenes are very long..

Now, all you need is a Belief sensor on an analog pin...
857  Forum 2005-2010 (read only) / Interfacing / Re: What do you use for female jumpers? on: November 07, 2010, 01:27:11 pm
Props on the Wire Wrapping.. not seen that in a while smiley-wink  pretty sure I used my last spool of 30ga teflon to make an electromagnet for son's school project..

Anyway, jumper sets are cheap if ordered online.. I'm in USA, so I limit the search to North America if I need em quickly, otherwise just do a normal ebay search for the suckers.  You can get a 70 pack of 'em of assorted lengths for a couple of dollars shipped.  Typically if you find a vendor you might want to check out what else they are selling, if they will combine shipping.. finding a 760 point breadboard for $4 or LED's at 100 for $3 from the same bulk Hong Kong vendor is common.. just be prepared that you might be waiting a few weeks for things to get there.  I generally use "buy it now" and stick to vendors that have done a few thousand ebay sales..there's many... also those outfits are great for component assortments like resistor kits..
858  Forum 2005-2010 (read only) / Interfacing / Re: What do you use for female jumpers? on: November 07, 2010, 11:52:32 am
Have you tried various ribbon cables.. they might be able to get you the inside and outside rows, but the middle might be tough.  Pin spacing in definately the issue.  "Repurposed" hard drive, floppy, and whatever else cables from a remaindered PC are great sources.  Time for that old Pentium 90 to die for a good cause- cables and connectors.  Don't forget to rip the drives out too, always a few good stepper motors and such in a floppy or CD drive.  If the drives are older, they very well could also have internal connectors and ribbon cables that might be coaxed into usability.  I currently use a floppy drive cable as a convenient push-on connector and cable for UART to my boarduino.

I'd normally warn against fudging a connector.. but, considering where you are already.... hehe
859  Forum 2005-2010 (read only) / Interfacing / Re: Help with connecting LED's on: October 30, 2010, 06:23:44 pm
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);
etc.

that defines pin 9 (etc) as an output, which also has the effect of enabling the internal pullup resistance on the pin.  If you forget to do this, you will get much less current on the pin than you might expect..

Also, remember that you really don't want to pull a whole lot of current from the pins, so if you are lighting more than a couple of standard LED's, or using high-power (high-current) LED's, then you are going to want to use an external transistor to switch the power rather than sourcing it from the chip/arduino directly

860  Forum 2005-2010 (read only) / Interfacing / Pixart/WiiMote Camera.. alternate hookup? on: October 28, 2010, 04:38:35 pm
Hey guys.. another item in the "gonna hook to the Arduino soon" bin I have is a broken WiiMote.. well, once I stripped it down, I discovered it was just a broken trace on the board.. but no loss, kids already bought a new one so I got a cool toy for the bin (like many, my kids provide me with plenty of broken, abused toys for me to abuse in turn).

I came across this VERY interesting blog entry:

http://arduino.cc/blog/2010/07/13/wiimote-light-follower-with-servo/

In short, the project is pretty standard... except for the hardware.  It seems that if you feed a Wii remote camera a clock signal (minor mod)  you can access ALL the I2C devices on the remote.. via I2C!!!  He came up with a way to access all those toys without desoldering the sensor and all that, which is awesome.  It will really open the usage of the camera component if the desoldering and such isn't needed.  Seems too good to be true, but go ahead read his stuff, looks to be working... and begs the question.. is the bluetooth I2C controlled and does that also work?  That's one cheap set of peripherals, including bluetooth, if this can work THAT easily..

Now, he uses a 24Mhz external crystal oscillator as his clock source.

Other than needing to rework timing, is there any reason that you couldn't use a 16Mhz clock signal instead... like the one we have sitting right there on the Arduino?

Interesting blog... and I think I may try this.  I can't see how feeding a lower clock rate would hurt any of the hardware, the worst problem would only be it not working...
861  Forum 2005-2010 (read only) / Interfacing / Re: Wireless mouse as cheap link to PC for arduino on: October 25, 2010, 03:50:06 pm
do a search on ebay for 433mhz (I think) RF link modules.  You can get em as cheap as $10 a pair delivered, if the docs are to be believed, they can function as a virtual-wire serial link with no further modification.

I've not bought or used them, but looks promising.  Sure Electronics sometimes has sold them (think sparkfun has too?) so I think the modules themselves are probably legit..
862  Forum 2005-2010 (read only) / Interfacing / Re: Arduino WIRELESS Communication on: October 18, 2010, 01:21:21 pm
Most seem to like the Xbee system, which is basically like a transparent wireless serial connection in most ways.. you can treat it as if the arduino is physically connected.

Controlling four motors (speed wise, I am assuming) is easy enough, you would use PWM output, and a power transistor.  Arduino would support 255 levels of speed control, from 0-100% of power.  Arduino can support PWM via extra software for up to fourteen channels (I think), but the "native" arduino has more than the four you would need.  Look in the "playground" section of the reference, it gives some good examples as well as some pointers as to where you can find information in more detail.
863  Forum 2005-2010 (read only) / Interfacing / Re: How to Purchase Servos on: October 15, 2010, 08:27:12 am
The steering does appear to be servo driven, the problem being that the outer case of the rolling platform is sealed.. epoxied or whatever, no screws to take it apart.  However, when the front wheels are steered or turned, there is definitely a gear train of some sort involved- so that would indicate a servo to me, without digging into much further.  The RC car has been purchased as a toy to be explored in more detail the next time I'm laid up and need something to occupy me... that will probably put it on the chopping block somewhere before the end of the month- though I'm setting up and planning for a Halloween setup for the yard as this month's main useless timewaster.  All in good time.

I mastered several games and a MMORPG before during my down times.. it is infinitely more fun to MAKE evil little robots than it is to blow up virtual ones...

By the way Applesauce- I like the way you think.  Most here set out to build an obstacle AVOIDING bot, your plan for the exact opposite, a bot that seeks out the walls and bashes into them-- great stuff.  You may want to consider mounting a Dremel or small drywall-destroying ablative armor.  If you build them cheaply enough, you could just have em explode on impact, eventually cutting their way through any defenses.  Really good first step in the whole "Crushing all resistance beneath my iron jackboots" phase.  I do expect dominion over, say, Hawaii or maybe New Zealand in exchange for the helpful input, you understand...

I've wondered about using biological rather than mechanical- but a laser-equipped hamster isn't as reliable as you might think.  That isn't to say that a laser-guide cannon that fires hamsters as ammo might not be an impossible (if messy) idea...  and also found out that one right we Americans hold very dear, the Right to Bear Arms, isn't all that useful, unless you want to catch salmon.  No opposable thumbs and always shedding.  Just one of those things that sounds great on paper I guess.
864  Forum 2005-2010 (read only) / Interfacing / Re: How to Purchase Servos on: October 14, 2010, 10:56:25 pm
Heh, well at least getting into the Arduino stuff has actually got me pulling things I tossed in boxes on shelves in the basement "to be fiddled with eventually" and actually DOING some things with them.  I'd come across something interesting, pull out the cute bits and shelf them, and toss the carcasses... did for years, as many here probably do.  It really adds up fast, so only keep the interesting parts, large carcasses anger spouses.  Use a couple of Rubbermaid totes or whatever and just shelf em.

I've got a medium tote that's just wall warts and power supplies.  Probably have a half dozen solid 5v and 12v regulated power supplies in there, a couple of DC-DC converters, and a couple of Nicad camcorder batteries in there too.  Another is motors and assemblies, probably have twenty small servos and steppers as well as a bunch of toy DC motors.  I have a fishing tackle box for miscellaneous small components.

I rarely spec any of it until I pull out something and want to use it.  Sometimes I don't bother reading up if I've got a few of something and I'd rather burn it up than read... operating out of what are essentially trash bins makes epic failures easy on the wallet...  often I have no idea how to use something when I shelf it (I've been gazing at a high-res single-pixel-wide CCD I "liberated" from a business card scanner.. still not shelved, so it's one that keeps tickling the fiddle itch.  I've got a couple of old cell phones I may strip for their nice little displays.  

The point is that this hobby is going to turn you into an electronics packrat probably, if you aren't one already.  If you can, get in front of it and try to get some cool stuff to play with...Just don't go too crazy or the spouse tends to get a bit flakey.
865  Forum 2005-2010 (read only) / Interfacing / Re: How to Purchase Servos on: October 14, 2010, 05:44:24 pm
Ebay, Ebay, Ebay.. from China on the cheap.  Look for R/C hobby servos.  You can find real deals on things like "9gram hobby r/c servos" at like ten of 'em for twenty bucks shipped.. just going to have to wait as much as 3 weeks for stuff to arrive.

R/C hobby stuff is one of the best sources, as they are usually designed to run at low voltage off batteries... I'm currently fiddling with a R/C car I got at Walmart for $7.  For that $7, I've got a full rolling platform, steering (servos), the whole thing.. and can even control via the very basic (4 switches.. forward, back, left, right) remote from up to 75 feet, according to the box.. begs for a couple of transistors and Arduino control.

Other than that-- Printers.  Old printers have some GREAT motors, as do scanners.  For low-duty, you can even rip apart floppy drives for a couple of servos, encoders, and other fun things.

Dumpster Dive and Ebay from China.... gonna be your best sources...
866  Forum 2005-2010 (read only) / Interfacing / Re: CCD line scan camera on: October 14, 2010, 11:31:47 am
If you are interested in those sensors and similar ones, you can often find "business card scanners" at flea markets and the like.  They use these or similar CCD's.  I recently ripped apart one that came my way, netting a nice little stepper motor, a couple of other useful toys, and a very similar sensor.  Epson CardScan I think it was.  Not even really read specs on it, but as set up, it was a 8-pin connection and seemed to be a standard-type module, made by someone called "MUST technologies".  The point is, it's the kind of thing which might be very well suited to fiddling with, especially with the Arduino.  If I remember right, I think it's set up as digital, SPI interface, memory mapped data.  Think it might be neat to mount on a stepper and add some optics, and give the arduino slow-scan (physical!) vision...

Point being, this is the type of module that you can get by ripping apart something that can be had for little cash or free, rather than purchasing (usually for some inflated price).

Get yourself some SCUBA gear.. jump on in, the dumpster's great for diving.....
867  Forum 2005-2010 (read only) / Interfacing / Re: Luxeon PWM Overdrive on: October 13, 2010, 12:42:22 pm
At least the module I got is mounted on what appears to be an aluminum slug- solder tabs for the LED on pads, etc.. I understand this is a common configuration for these power LED's.  I'd like to think there's some type of sinking compound there, rather than just drawing the heat off the leads.. I have some sinks around from various things, one I reclaimed from a car audio amp which ought to be able to dissipate a heck of a lot of heat.. if heat really is an issue, I'll just slap the slug to that beast with some compound... I haven't yet gone as far as considering chilling the whole diode.  I was going to say that would be overkill, but the whole idea is overkill from the beginning, so to speak, anyway.  Note my use of the word "yet".  I've used circulated baby oil as a coolant before... fishtank bubbler+airstone+mineral oil= nonconductive but really dang good heat drawoff from just about anything.... Yes, I know it's a terrible kludge, but that's the kind of foolishness I find the most amusing... but I doubt I'll go as far as milling off the plastic to get close thermal contact... though that's an idea too...

smiley-wink

Of course I could just go and get a 5w or 10w (or more) module- but that's too easy.  I mean, I'm a shutterbug... I have two studio xenon flashes and a couple of old second-hand-store flashes I use for fill, or I could build a xenon strobe trigger, or "repurpose" one from a disposable camera (great source for em, by the way)... but that's almost too easy.  I'm digging the Arduino because it allows me to either take a simple idea and make it needlessly complex, or simply come up with my own ways of doing whatever someone else has already done more cheaply, efficiently, and with substantially less grief.. that IS why we're here, at the base of it, IMO.... lol.  I'm learning more about electronics NOW, because I want to fiddle with particular things, than I EVER did during actual education on the subject matter, a few decades back.  In this respect, both as an educational tool and just as a very flexible "toy".. it's amazing.  Combine that with some of you that really DO have the hardware expertise and a friendly forum like this.. well, suffice to say that I spend time tossing around and prototyping creative (or just plain silly) ideas rather than playing "Left 4 Dead 2" as a timekiller... and that can't be a bad thing.  Being a stay-at-home dad has a high "Brain Rot" quotient.

A "good" solution can most likely be bought... probably cheaper and better than I'll ever make... but I think (at least in my case) that the win really IS found in the journey, and not the destination.  My first project (and even started a blog on it) was a camera controller- been done many times- "camera axe" is one that's pretty impressive, not far from what I envisioned for my own design.  My own design, which became a HDR trigger and such, used many of the same ideas.  The thing is, it had been a long time since I actually USED ohm's law.  I had to dig around and remember and re-learn voltage dividers and amplifiers and optoisolation.. after a VERY long time since I used any of that.  The time, cost, parts that went into it- not huge, but the benefit far outweighs the "overpaying" for a camera trigger, in my mind...
868  Forum 2005-2010 (read only) / Interfacing / Re: Luxeon PWM Overdrive on: October 13, 2010, 08:52:08 am
Wowsa, wouldn't have considered that as a point of failure, mechanical torsion from induced field.. now that's my kind of failure.  The math is out there, I'm sure.. that strong a field without a coil, not something you'd normally think of right off.  To be clear, I won't be crushed if the Luxeon doesn't survive more than a few hours of operation.. 3-4 hours is all I really need for the kiddies.

So as I diddle with this, I've found a TIP120 lying around and will probably use that for control... somehow I don't think the little 2222's are gonna take this kind of abuse..
869  Forum 2005-2010 (read only) / Interfacing / Re: Luxeon PWM Overdrive on: October 13, 2010, 08:23:18 am
Well, Phillips carries the lumen data out to 800ma, only slightly over twice the rated current; and that's based upon full-time illumination (with active cooling via fan and heatsink).  The lumen output stays fairly linear, though I'm sure it jumps the cliff at some point..

This is mainly a conjecture thing over a cup of java at the moment, might do a little more research.  It's not particularly practical of course, as we have both noted- the smoke test will the best determining factor, as the specs have been left on the side of the road.

Just occurs to me that if the desired illumination from the LED is intermittent (like my strobe thought) then the heat factor may be less of an issue and the LED might be able to handle very short, very high current pulses.  Haven't seen any others having done this, but an interesting thought experiment that may need to see a breadboard..

What I have in mind is an LED "lightning" strobe (maybe even with a sound ouput.. but I digress) for the front of the house for halloween.  I've kinda decided my yard will be animatronic this year if I can pull it off, and using Arduinos to do it if possible, even if it doesn't make a lot of sense to do so.  Sort of an Everest "because it's there" thing, I think.. we'll see if I actually bring any of it to fruition.. (another pet project, I've taken to "possessing" a discarded Furby toy as a concept at some point.. though a Teddy Ruxpin would be better... I'm committed to the idea of reverse engineering one of these toys and making it as demonic as possible)
870  Forum 2005-2010 (read only) / Interfacing / Luxeon PWM Overdrive on: October 13, 2010, 08:04:51 am
(excuse any typos, half-blind from playing with this..)

So, picked up a 1w Luxeon for cheap money for giggles.  White, throws an insane amount of light.  Now I've been doing reading on the best setup with these (ideally a constant-current source with internal feedback), and then immediately doing the exact opposite, as is my usual experimentation method (I love inhaling vaporized doping materials and plastic).. 2 AAA batteries and a 2 ohm resistor later, I'm happily blinding myself.  I know, I'm underdriving it (3.17v from batteries, with an LED Vf of 3.42v, hehe.. tolerances?  specs?  Humbug!)

What occurred to me is that the whole current-limiting thing is to prevent overheating and thermal runaway.. the limiting factor is the heat being generated... in other words, it could probably take a LOT more than 350ma spec, if cooling were taken into account..

So, anyway, if my desired application for the Luxeon is basically a strobe light whose duration will be measured in milliseconds... there's little time for heat issues.

That being the case, how high a drive current do you think a 1w luxeon could take, assuming the Vf is run at rating, 3.42v?  Of course it will be out of spec.  Then, carry that forward, and what do you think the current/lumen capacity might be... especially if the strobe pulse is quite short or managed via PWM?
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