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601  Using Arduino / Programming Questions / Re: I didn't quite understand 'ACK' on: July 23, 2012, 11:52:12 am
The commands of the SmartGPU either return ACK or NCK (no acknowledgement). How do I respond to those commands?

Did you look at the linked "Command Set" document or just the datasheet?  After taking a quick look at both, it's clear the Command Set goes into much more detail about the control and communications for this device.
602  Topics / E-Textiles and Craft / Re: 3D printer help. on: July 23, 2012, 10:23:18 am
Well, I don't want to disuade you Duane.  To be clear, by "significant learning curve" I meant you'll probably have to devote over a dozen hours total if you want to use many of the capabilities in modern consumer/non-professional grade 3D CAD systems, as opposed to just completing a half-hour tutorial that will only teach you how to draw striaght lines and simple curves.  I didn't mean to imply it would require weeks or months of study to get any use out of a CAD program!
603  Using Arduino / General Electronics / Re: Are there any cases good for holding arduino and electrical related stuff? on: July 23, 2012, 10:06:25 am
As Constantin suggested, any hardware or related store (ACE, Home Depot, Lowes, Farm and Fleet, the aforementioned Harborfreight, etc...) would have some good parts cases.  Some department stores, like Sears, or arts and crafts stores can also be worthwhile to investigate.  

If you are looking for something stationary to put on or near your workbench, don't rule-out office supply stores.  For example, I recently bought several stackable bins and modular shelves that nicely store larger electronics components and multiple small PCBs, like Arduino UNOs and Megas.
604  Topics / E-Textiles and Craft / Re: 3D printer help. on: July 23, 2012, 09:45:18 am
I really need to replicate myself first to get a grasp of half the things I would like to do.

This could be very interesting but take a year or two of my life :-(

Does anyone have any experience of the learning curve ?

Well, here's my experience for what it's worth.  In the spring of this year Makerbot stopped producing their smaller 3D printer, the Thing-o-Matic, to focus on the Replicator.  So they were selling their unassembled remaining kits for a discount of hundreds of US dollars (basically for a little less than half of the current price of the Replicator).  I decided to get a Thing-o-Matic kit.  Even though it came to me in a complete kit with well written documentation available online, it took me a couple of two-day weekends and a few evenings after work to get it assembled and running.  Mind you, that's without any major problems and only a couple of instances of backtracking that didn't cost much more than an hour each. Once it was running the control software was fairly easy to use.
The Repraps brought up earlier in the thread are smaller, have less electronics to wire-up, and don’t have cases to put together.  So they’ll probably be somewhat quicker to assemble, but be prepared to invest a significant amount of free time before you can use them.

Of course if you want to make your own designs you'll probably need CAD software of some kind (as opposed to just downloading STL files made by other people).  If you're not already familiar with either paper drafting or CAD there can be a significant learning curve.  Although the interfaces and other aspects can differ quite a bit, once you get the fundamentals it usually isn't a big hassle to go from one particular CAD program to another.  There some decent free programs as well as a few commercial packages ~100 USD that would be more than adequate.  For personal use, I have ViaCAD Pro v8 (I splurged a bit, it actually cost ~250 USD but they have a 100 USD version too) as well as DesignCAD 3D Max 20 (picked the latter one up during a clearance sale for ~39 USD) either series would be a good investment if you are serious about using them.  I don’t have that much experience with free CAD software, but there seem to be some decent options currently available.
605  Using Arduino / General Electronics / Re: Time for a new iron on: July 23, 2012, 08:57:03 am
That is a Hakko 936 clone from China.

That model is a retired product  It's not for sale any more...

This is it's replacement Hakko 926 clone from China, perhaps you meant this:

Sorry, that's the one I meant. I'll probably pick one up next week.

It seems to be have good reviews.

I recently bought the one (the product number 10707) from Sparkfun.  After a few months of use on spare-time projects I'm quite pleased with it.  It heats up reasonably quick and it works well even with non-lead solder.
606  Topics / Education and Teaching / Re: Building with My Own Children on: July 20, 2012, 05:03:56 pm
Though they are still relatively new, I've heard good things about about littleBits.  They seem to be more free-form than Snapciruits in that as long as you follow the color coding system, you can mix and match "bits" to a great extent (had to stop myself from typing "quite a bit" smiley-wink ) and still get a circuit that does something.  They also are something your kids could probably put together themselves (under supervision).  Of course, like Snapcircuits they are something your kids will grow-out-of; so I'd use them as a fun introduction to electronics concepts and a supplement to whatever you do with ardiuno and conventional electronics.

That's all I can add to the excellent advice you've already recieved.
607  Topics / Device Hacking / Re: Wheelchair Hacking on: July 20, 2012, 04:38:33 pm
There's lots of potential with this setup, the primary limiting factors are going to be how much time and money you want to expend tricking-out your new chair. smiley 

Something not yet mentioned would be sound.  Whether it's just hacking an MP3 player board to controls on an armrest, or doing a full custom sound system including speakers, radio, and microphone; you've got some options there as well.

With wireless modules like Xbees, you could also turn lights and some appliances on and off on command, or automatically as you moved around your home.

I have some other ideas but they start getting into the "way too expensive and/or eccentric" territory.   
608  Using Arduino / General Electronics / Re: Time for a new iron on: July 20, 2012, 03:43:32 pm
The incident he describes is an iron projecting its heating cartridge forward, which while it shouldn't happen, isn't going to harm a user since 'proper' use will not result in pointing that projectile at oneself...  And even improper use would not result in a life threatening injury... Hence my comment, which was a response to yours about the 'safety' issues...  Life is not safe... reasonable people don't expect it to be.  In fact it is guaranteed to be terminal.

So while soldering you've never, even momentarily, had your other hand or arm in straight-line path of your soldering iron?  I don't mean just right in front of it, it could be on the other side of PCB or inches away grabing a solder wick, etc...  Recall that Doc mentioned the heating cartridge's final resting place was the ceiling, if he was in a room with standard height ceilings that cartridge had plenty of energy to hurt someone.  Also while losing a chunk of a hand or arm isn't fatal, it's something most people generally want to avoid.

All of that is really besides my main point however... The Ungar soldering iron in question was not only potentially unsafe, it was completely unnecessarily so.  Some risks are innate and intrinsic to an activity or device, the "nature of the beast" as it were.  However, as previously stated, if an electrically powered soldering iron has a chance of any part of it exploding during ordinary usage it is seriously flawed.  Even an inexpensive hobbyist type of electrically powered soldering iron that is decently treated should have no more chance of explosion than a well made and properly used hammer has of falling apart in your hands.  Finally, setting aside the danger it might mean to the user, why is it so unreasonable to demand that a soldering iron not violently destroy itself in the course normal usage?!?!

I don't expect life to be to completely safe, not only is that impossible it would be boring as well.  However in my experience, reasonable people don’t usually take unnecessary risks.  If they choose partake in activities that have innate risks, they also mitigate them to the extent it’s practical to do so.  That’s not being risk adverse, that’s being smart!

And there isn't much to compare today, with the folks who created devices like I mentioned with vacuum tube era technology.  Given the vast improvement in technology available to the general populace, we should see a vast improvement on what was created then... and we haven't.  In part because people worry too much about things like 'safety'.
Ok now I’m starting to think you are just trolling me, either that or you are letting unchecked nostalgia seriously delude you.  
Here’s why, we are having this discussion on an internet forum dedicated to artists, hobbyists, and various other non-professionals (although there are professional engineers posting as well) from across the entire globe using palm-sized microprocessor boards that are many orders of magnitude more computationally powerful than most computers existing during the 1960’s.  Furthermore, the people on this forum are using these devices to improve or change any almost conceivable aspect of their daily lives, or just for the heck of it.  You can read about numerous home automation projects, robotics, remote sensor networks, computerized telescopes, home weather stations, etc… even high altitude balloons and rockets with multiple sensors and telemetry!  What more do you want flying cars, jet packs?  Spend 15 minutes with Google and you’ll probably find someone, somewhere, at least attempting any manner DIY project you can think of, you just need to open your eyes a bit.

In any case, I doubt continuing this digression will have much further use or interest to anyone.
609  Using Arduino / Project Guidance / Re: Quadcopter level? How can I measure it? on: July 20, 2012, 01:37:22 pm
Since you mentioned thinking outside the box...  How about incorporating some off-drone hardware?

If your quad-copter is also tracking two or more stationary points of known and different heights above the ground, it could use trigonometry to get the angle of a striaght line directly between a sensor and point.  If the sensors were mounted on each of the arms supporting the four rotors the angles can be compared and used to estimate how much the drone is tilted in at least a few different directions.  This is basically how some sattelites and space craft use specific stars to determine their position and orientation.

Alternatively, you might be able to use something like suntracker on each arm, either tracking the actual Sun or a single fixed point on the ground.  However, to give you the information you need each pseudo-suntracker must measure both the horizontal and vertical angles accurately and fairly precisely, along with sensors that are extremely directional (so simply tracking any RF command signal is doubtful to work).  Once you have that information, you then have what amounts to plane defined by four points which shares the same tilt as your drone.  While using the Sun wouldn't need any extra physical setup, it would require the drone to account for the movement of the Sun as time passed (and obviously wouldn't work at night or on cloudy days).  Some sort of active beacon or reflector could be used anywhere you are able to set it up and any time, but it adds to your logistical considerations.
610  Using Arduino / General Electronics / Re: Time for a new iron on: July 20, 2012, 12:06:44 pm
Except the situation Doc described wasn't due to carelessness.  The product had a dangerous defect that occasionally caused the heater cartridge to explode, potentially just due to powering it up.  An unpowered soldering iron can't fulfill its designed function so turning it on has to be part of proper and intended usage.  Also, manual soldering irons require being held during use; picking one up by the intended handle shouldn't be a problem either.  So in this particular case you can't just blame it on "carelessness" if a faulty heating cartride vaporizes during normal use.  

Furthermore, if all such soldering irons of that period had the same propensity to explode you might have some point that this would have been potential risk should have been expected by anyone using a soldering iron at that time.  However, that wasn't the case.  There were a number of electrically powered soldering irons on the market at the same time that were just as good at fulfilling their intended function without this particular risk.

I believe that if a commercial product unexpectedly and unnecessarily causes significant harm when used reasonably for the product's intended purpose it is the responsibility of the manufacturer to either modify the product to remove the potential danger (at least during normal usage) or stop making the product.  If they refuse to do either, I also believe it is right and proper for society/governement to force them to choose one of those options.

Finally, I don’t know why you’re waxing poetically about some supposed “lost golden age” of scientific and technological discovery.  First it has nothing to do with potentially explosive hand tools.  Second, while you won’t get the instructions or materials in your Wal-Mart, search “chemistry” on Amazon and tell us in all honesty how knowledge is being suppressed.  Also, I see your DIY particle accelerators, and raise you DIY fusors!
611  Using Arduino / General Electronics / Re: Time for a new iron on: July 20, 2012, 09:42:53 am
Ungar made an iron in the 60's that has a famous history... it seems that the iron has a replaceable "Heat Cartridge" and replaceable tips... The Heater occasionally fail and vaporize internally... since it was "plugged it in it only had one way to go out and it would do so. Once I picked up my Trusty Iron only to have it go off like a small cannon and embed the heater cartridge in the ceiling.. (TRUTH).

Wow, you state it was the 1960's, but even back then it's amazing that someone could get away with selling a commercial product that could fail in such a spectacularly dangerous way during normal and expected use!  It's a good thing you didn't point the iron toward's your other arm, or anything else you want to keep functional, when you picked it up that time.
612  Using Arduino / General Electronics / Re: Cheapest Arduino programmer ever? on: July 20, 2012, 09:28:22 am
Off topic but I find the enthusatic, though haphazard, use of image editing on the product photo from eBay to be amusing.  Why go to the trouble of adding thought ballons, etc... to your widget's picture if you don't bother to place them where they won't overlap with areas that are the same color or otherwise make them less visually discernable? smiley-roll
613  Using Arduino / Project Guidance / Re: Controlling a dorm fridge with an arduino instead of built in thermostat. on: July 20, 2012, 08:53:16 am
Looks like this is what I would want:

120D10. 120 VAC line, DC control.

Yes, that looks a good fit for your application. 

Although this particular SSR will only need a low DC current (4mA, much lower than the ~20mA an arduino can sustain as an output) for 5VDC control, just for future reference you should note the datasheet section called "Control Current Calculation".  This is because the relationship won't necessarily be the same, especially for different types, but relays' control circuit current draw will vary with voltage.
614  Using Arduino / Project Guidance / Re: Controlling a dorm fridge with an arduino instead of built in thermostat. on: July 19, 2012, 05:03:50 pm
You've got the basic idea. 

The next step would be to determine what you can from the existing thermostat, for instance the voltage and current rates will help you look for one suitable for use with both the fridge compressor and an arduino.  Also keep in mind that you'll want a relay where the control signal is not only 5V or less, but also <= 20mA (i.e. make sure it's something that the arduino can actually control before buying it).

With regards to temperature sensors you've got a range of options that will work with an arduino; from temperature only to combined temperature and humidity sensors.
615  Topics / Robotics / Re: Some robot "behaviors" on: July 19, 2012, 10:45:43 am
Building on the photoresistor ideas, you could have the robot be both light-fleeing and light-seeking at the same time.  Basically, your robot would have three sections on the photoresistor's output range: "Too Dark", "OK", and "Too Bright".  All you would need to do is define two specific analog input values as thresholds and have a specific function to respond to each of the "Too Dark" and "Too Bright" conditions (usually the "OK" condition would just let the rest of the sketch do its thing).  An example would be a robot that's "afriad" of an unlit room, or as you suggested the shadow cast by a table, so it tries to find a brigther area; is fine in a normally lit room and/or outdoors; but backs away when exposed to a nearby camera flash or other very bright light.

This can also be the foundation to more complex behaviors, especially if the exact response can be varied based on readings of other sensors. 
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