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616  Using Arduino / General Electronics / Re: Need help finding something (type of button) on: July 17, 2012, 09:51:14 am
Are there anything kind of alphanumeric sequences (series of numbers and/or letters) printed on it?  If there are one of them is probably a part number.   Another route could be to search for the name of DDR pad it was originally, someone might have done a tear-down on one and have more information about the parts.
617  Using Arduino / General Electronics / Re: Can I use this solar powered battery charger to recharge my AA batteries? on: July 17, 2012, 09:05:13 am
I'm not Doc, but for the more common (and most uncommon) ICs both digikey and Jameco are decent sources.  Sure they'll be more expensive than you might be able to find on e-bay and electronics wholesalers(with some the term is used loosely); but they have an dependably acceptable level of quality for the products they sell (versus the hit-or-miss you often get by extreme bargin hunting), actual customer service (including basic stuff like datasheets and other documentation), and significantly faster delivery if you are in North America.  I also like to patronize the smaller online electronics vendors (like some of those listed on the Arduino Distributors list, but they of course have a more limited selection.
618  Topics / Science and Measurement / Re: Piezo beep with flash detection on: July 16, 2012, 04:12:11 pm
It's very possible to do what you want, and it isn't very difficult. 

With regards to latency, the only delays will be the signal propagation down the wires and how many clock cycles your code requires to detect the flash and then output to a speaker.  Even with very inefficient code, their probably won't be a noticable delay (to human) between the detection and sound. 

You should start by looking the Playground's example code for light sensors and audio output devices.  If you want to do something else with the sketch while waiting for a flash, you should also read about interrupts in the Reference section of the main website.
619  Using Arduino / Displays / Re: Repurpose Palm LifeDrive TFT on: July 16, 2012, 03:34:18 pm
Ok, I see and understand my mistake now.  I knew that this display didn't have any serial communication to the outside world, but I thought the driver had a more sophisticated addressing system.  Instead it works more like a basic CRT display.  Thank you for identifying and explaining my error to me, TCWORLD.
620  Using Arduino / Motors, Mechanics, and Power / Re: Driving a noisy DC motor on: July 16, 2012, 03:21:19 pm
I would suggest that the range and physical distance between all the sensors would make this approach tricky, however our arduino is mounted close (6 inches) away from the motor, which probably isn't helping.

There's nothing to prevent you from sheilding each wire, except of course cost and occasionally space and weight concerns. smiley-wink

While it might not be the only source of your issues, you are correct that the proximity is arduino to the motor is a potential culprit.  The good news is shielding the arduino will be cheaper and easier than the wires, basically all you need is a metal box or fine mesh cage to put it in.  It's something anyone with basic hand tools and common materials should be able to build.  Or if you would rather spend money than time, there are metal cases designed to house arduinos.  Just remember, when you mount the arduino board in the enclosure it must be completely electrically isolated from the conductive exterior.  Otherwise you've just created a big antenna for the all the stray EM fields instead of a shield against them!  It also helps to make any access ports (e.g. to feed power and data wires through) as small as possible.
621  Using Arduino / Motors, Mechanics, and Power / Re: Driving a noisy DC motor on: July 16, 2012, 01:56:46 pm
It can get expensive (and bulky, and heavy) but as a last resort, putting the signal and return wires in EM sheilding with its own earth ground usually works (especially if it's possible to put shielding around most of the sensors as well).  These days there are a number of options like wire mesh gaskets, composite EM shielding materials, conductive elastomers, etc....  Here's a link to a company on your side of the pond that specializes in electro-magnetic sheilding to give you some ideas of what's available (Note: I've had no experience with them, they were just the first UK company that popped-up on Google with a large range of EM shielding).

However before you go on a buying spree, some of the venerable forum greybeards may have cheaper and easier, but still effective, solutions.
622  Using Arduino / Motors, Mechanics, and Power / Re: Can a battery explode on: July 16, 2012, 10:54:48 am
Thanks for all your help. I know use non-recharable batteries and modified the project so that nofire hazard is possible. Thx.
So instead you will use resources that pollute landfills and you have to keep buying new batteries.

Ease off a bit on the guilt, I'm all for reducing the amount of trash a person sends to the land-fills but not at the expense of any one's home or driving them away from tinkering and DIY electronics projects.  A person is more likely to do the other two "R"s (Reduce and Reuse) when building things for themself and not forced to only rely on commerically made products.

One thing I should clarify though to otzi, the most risk involved in with recharagable batteries is while recharaging them.  So much of my warnings were for custom designs with one or more non-replacable recharagable batteries and a built-in recharging circuit (although you still don't want to expose any battery to temperature extremes, especially heat).  So if your design uses standard sized alkalines; you should also be able to safely use a rechargable battery of the same size, provided you recharge them with a charager ment to be used on that size and type of battery.
623  Using Arduino / Displays / Re: Repurpose Palm LifeDrive TFT on: July 16, 2012, 10:22:45 am
And can the arduino read data from an external data source (there isn't enough to ram to store one frame on an arduino) and output the 24bit of colour data (or even 1bit) in 1 instruction clock?

Why does all this have to happen in 1 instruction clock?  ronalda's planning to make a GUI interface for a thermostat, not a high-end graphics workstation.smiley-razz  As long as you can write to the driver during a given clock tick you can change the output of the display.  The read time from the source file and any further processing aren't barriers, no matter how long they take the display will just stay at it's current state until given something else to display (the driver IC must have a system buffer of some sort, there's no way it's processing every pixel in parallel!).

The real time-related issue of concern is the refresh rate, long as the display is updated faster than ~24 frames per second (fps) most people won't notice delay for video.  I'm not suggesting that an arduino could pull-off those refresh rates with this display, but rates of single digit fps seem possible.  Unless this project includes live video feeds of ronalda's heater and AC equipment, even a few fps would probably be sufficient.

Again though, this is not something a novice should try cutting their teeth on, that's one of the reasons why I mentioned using an LCD.  Not only could a monochrome text or graphical LCD do the job, there are many that already have Arduino tutorials and/or compatible with exisiting libraries.  Also some are rather inexpensive if you don't need them to be very big, e.g. the 84 x 84 Nokia 5110 graphical LCD is ~10.00 USD at either Sparkfun or Adafruit.
624  Community / Products and Services / Re: which arduino board is better on: July 13, 2012, 04:18:32 pm
Thanks for the tip gentlemen!
625  Using Arduino / Programming Questions / Re: what is this define? on: July 13, 2012, 04:12:07 pm
Without seeing the rest of the code, I guess it's some way to handle both the "beta versions" of the Arduino IDE (i.e. all pre-v1.0 releases of the IDE) to the v1.0 and higher versions of the IDE.  There were a few fundamental modifications in the jump from 0.23 to 1.0 to core IDE libraries that made some previous community-made libraries non-functional unless different core libraries were included.
626  Using Arduino / Displays / Re: Repurpose Palm LifeDrive TFT on: July 13, 2012, 04:01:29 pm
Thats its datasheet (or at least one for an equivalent display).
http://beyondinfinite.com/lcd/Library/Sharp/LQ038J7DH52.pdf

They are literally just the display and a driver IC. These are not a simple thing to interface too, and an arduino is simply not fast enough.

But don't let that stop you having a go smiley


After reading the linked datasheet I agree interfacing won't be simple.  However, what makes you think all arduinos are too slow to interface with it?  Page 8 of the datasheet states that the "Clock frequency of source driver" (i.e. the driver IC's clock frequency) has a range of 9.3 to 12.1 MHz.  Last I've checked 16 MHz was faster than 12.1 MHz and the last few 5 VDC arduino designs have a 16 MHz system clock (that can even be slowed to within the range of the IC driver, though it shouldn't be necessary to do so).
627  Topics / Product Design / Re: Arduino fur industrial use? on: July 13, 2012, 03:44:33 pm
Nice finds CrossRoads, thanks for sharing!
628  Using Arduino / General Electronics / Re: Can I use this solar powered battery charger to recharge my AA batteries? on: July 13, 2012, 03:33:07 pm
My point was that there can be a situation when the batteries are fully charged, but the solar still pumps more current into them. What's going to happen then?

As perviously stated, it depends on the battery type and capacity! 

Some, like NiMH and Lead Acid batteries (automotive and gel SLA) it won't be a problem, provided the current is kept small enough to function as a trickle charge otherwise it can damage the battery and at high enough currents lead to the production of hydrogen gas (always very flammable in normal air and potentially explosive if sufficiently concentrated).  Other battery types you'd have to have a way to automatically electrically disconnect a fully charged battery from the solar panel to prevent it from being overcharged.  LiPos, for example, are easier to damage and have a lower current threshold for self-ignition or explosions.  With only 100 mA of overcharging the more spectacular failure modes are still possible (especially with small capacity LiPos and Li-Ion), but the far more probable issues will be faster than normal degradation of the batteries and/or total failure where physical damage is limited to the battery itself. 

In any case, even if you are using the cheapest possible recharagable batteries, it's usually more cost effective, and always a bit safer, to prevent minor overcharging than to live with its consequences.
629  Topics / Product Design / Re: Arduino fur industrial use? on: July 13, 2012, 02:59:36 pm
As an example of a more robust Arduino derivative, Rugged Circuits offers a version of the UNO with a number of modifications to decrease ESD susceptability, protect the I/O pins from shorts to ground and higher voltages than the stock UNO, and allow it to be powered with upto 24 VDC.  I don't think they went so far as to use industrial temperature (−40°C to 85°C) rated components, but since only the ICs and perhaps one or two other parts would need to be changed, it would be possible but somewhat more expensive per board to do so.
630  Using Arduino / Motors, Mechanics, and Power / Re: Can a battery explode on: July 13, 2012, 02:31:38 pm
So lets say a normal AA battery can not burn my house down if it is shorted or exposed to heat (max. 45°C).

It would be rather unlikely.  However if causes the wrong thing to catch fire, the smallest spark can cause a house to burn down just as much as any other ignition source. There some steps you should take anytime you want to use a battery in a custom design and be assured of safety:
  • First and most importantly, educate yourself on the battery type(s) you plan to use.
  • Second, think about the operating conditions (both the electrical and environmental conditions) you will be subjecting the battery to and if that poses any possibility of stressing the battery in a way that makes a fire or explosion more likely.
  • Third, if necessary modify your design in order to use the battery safely. This also includes changing the battery type to a non-recharable type, like common alkalines.
  • Forth, if for some reason it isn't feasible change your design to eliminate the possibility of fire or explosion; put the battery in a durable, non-flammable housing and isolate it as much as practical from flammable objects while providing as much ventilation as possible. Proper battery selection or modifying the circuit is always prefered to this last step, only go this route if there aren't any other realistic options.

Those are some general rules, more detail advice would depend upon the specifics of the application, operating conditions, and battery type involved.         
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