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1  Using Arduino / General Electronics / Re: Spontaneous breakdown on: July 02, 2014, 10:28:59 am
Yes, I do realize that. That's what I said in the original post - "My assumption is that the MEGA8U2 got fried".

Brownout caused by the faulty USB charger, or the entire grid?
Charger seems to be fine. Grid is another story. The location in question is in the center of my city, which means old installations and most likely even older substations, however I didn't experience any other issues in the days leading to the malfunction. There is a window of about 8 hours each when I'm not around, then the timer shuts down the power until morning.
2  Using Arduino / General Electronics / Re: Spontaneous breakdown on: July 01, 2014, 10:32:29 am
Original socket is soldered to the board. In it I placed a ZIF socket.
I don't think those connections are bad, since the chip works normally once I program it in another board and return to the damaged one.
Voltages are OK, 4,5V on 5V rail and 3,28V on 3,3 rail when powered by computer USB.

I understand I don't need to lose entire flash memory for it to stop working, but I would not expect the bootloader to work while main program shows no sign of live at all.
3  Using Arduino / General Electronics / Spontaneous breakdown on: June 30, 2014, 12:22:58 pm
I have a puzzle on my hands and I thought I'd share my thoughts and problems with you guys.
I have an Arduino Uno (hooked up to two IR LEDs in parallel), running a simple TV remote control program (just simulating pressing a few buttons, then it enters the empty loop). Arduino and the two TVs are outside, in a metal box which is exposed to the Sun and rain. Water does not get inside and Arduino is dry and in shade. Arduino is powered by a genuine iPhone USB charger. The TVs and Arduino are turned on and off by a timer (cutting the power in the evening and returning it in the morning).

The setup worked for about a month when some time last week it stopped. Today I got to examine the Arduino and observed the following:
There is no visible damage to the board.
When connected to a PC via USB, Arduino is not recognized.
IR LEDs are functional.
The program seems to not work (it got lost?), neither in this or the second Arduino, however the 328 accepted new programs (Blink example) when placed in another board without issues, and keeps working when returned to the damaged board.
Even with a new 328, when connected via USB, the board is not detected.

My assumption is that the MEGA8U2 got fried, possibly by a lightning strike (we had a few thunderstorms last week). That would explain the USB issues, however, no other equipment or electronics was damaged and I'm not sure if that would explain the loss of flash memory containing the program I wrote, but not the bootloader (the 328 readily accepted new programs).

One thing I will mention, even though I can't think of a reason why it would be the source of the problem, is the fact that I've put a ZIF socket in the original socket. It sits firmly and appears to make good contact.

Has anybody experienced a similar issue?
Any thoughts?
Thank you.
4  Using Arduino / Project Guidance / Re: Anyone have a 3d printer? on: May 05, 2014, 12:44:10 am
True, but in order to get to the mold stage one needs to make a final prototype. I've checked and this can be expensive. For the cost of getting someone to do it I can almost buy my own printer. Once I have a good prototype I can have a mold made for production runs.

You would use a service like http://www.shapeways.com . They are not that expensive.

Even if you already did have a printer and that part didn't cost you anything, I think it would still be more expensive in material to print several thousand units than have them injection moulded.
Then you have thousands of hours of print time. Those cost too.

Edit:
All this being said. There could be alternative ways. Perhaps you don't need a custom case? Can you get by with something already existing? There are project boxes of countless shapes and sizes made of various materials, so unless your product absolutely can't be boxy and needs protruding parts, through-holes or similar features, using existing, standard enclosures might be the way to go.
5  Using Arduino / Project Guidance / Re: Anyone have a 3d printer? on: May 04, 2014, 03:58:37 pm
3D printing is pretty expensive for mass production and for the price of a good printer you could cover a good fraction the cost of the mold for injection molding. After that the actual cases are pennies a piece.
So it boils down to just how massive do you expect your mass production to be? Is it hundreds of units, or tens of thousands or millions?

Recently I've seen a very expensive 3D printer (full colour binder jet) and while the finished item is a nice toy with working interlocking gears, the surface finish was definitely not what I would like to see on a final product which is supposed to have a professional look.
6  Using Arduino / Project Guidance / Re: How can i take the best sensor values ? on: April 26, 2014, 10:14:23 am
No significant difference.
They both seem a bit pricey, though. For the same amount of cash, you can get 10 of them at ebay.
7  Using Arduino / Project Guidance / Re: How can i take the best sensor values ? on: April 25, 2014, 01:42:19 pm
I have no idea what your country's legislation considers comfortable, so I'll skip the actual numbers and proceed to mention that in most spaces temperature and humidity are fairly even.
A notable exception would be near the HVAC vents where both temperature and humidity might be well within the acceptable limits, but still be uncomfortable. I personally don't like sitting in a flow  of air from the air conditioning unit. A temperature sensor alone will not be able to detect this issue.
8  Using Arduino / Project Guidance / Re: Apply force against motor or servo direction on: April 25, 2014, 01:35:32 pm
Yes, the clutch would provide enough friction for the motor to transfer the torque during regular operation, but would slip if someone tried to force it out of position. The actual position of the moved part would be monitored by the encoder.
9  Using Arduino / Project Guidance / Re: Apply force against motor or servo direction on: April 24, 2014, 10:58:50 am
I'd go with a stepper (or a continuously rotating servo), a clutch and a rotary encoder.
10  Using Arduino / Project Guidance / Re: I'm new and have a very basic questions on: April 23, 2014, 03:17:33 pm
There are smaller boards like Nano. It too has 6 PWM outputs smiley .
You could use a standalone microcontroller, such as ATtiny45 or similar. It's true to the name and really is tiny (only 8 pins, two of which are PWM).

Yes, there are Arduino simulators out there, but I haven't used them really and since I have a few boards, I can always test stuff directly so I don't need them. You may find them useful until you get an actual board, though.
11  Using Arduino / Project Guidance / Re: Biphasic square waveforms on: April 21, 2014, 12:59:56 am
Negative voltage is discussed here
http://forum.arduino.cc/index.php?topic=22651.0

Are you building a defibrillator? Because if you are, I have to say it doesn't sound like a very good idea.
12  Using Arduino / Project Guidance / Re: Long range (10 meters and up) IR transmitter and reciever on: April 08, 2014, 03:45:52 pm
You should also specify what "10 meters and up" mean.
In this case the maximum required range is more important then the minimum.

Define "tiny cars". How big is tiny?

Is all this supposed to work inside or outside? Is the IR coming from the Sun going to be a problem?

Why not demodulate in hardware? There are cheap existing solutions, packed with an amplifier, just plug and play.
13  Using Arduino / Project Guidance / Re: Where to begin here...? on: April 08, 2014, 02:04:10 am
Well, that's not as interesting smiley

Anyway, you should start with each module separately. Get an LCD running and counting down on its own.
Then figure out the pressure sensor, or you could use a simple switch. I don't think you need a measurement of the pressure, just the information that a threshold is passed. A spring loaded switch would do the job as well, I suppose. Perhaps sitting surface of the chair could have a flap over its entire surface that is sitting on the switch. Something simple.
14  Using Arduino / Project Guidance / Re: Where to begin here...? on: April 08, 2014, 12:45:12 am
Is it a bomb?

Yes, Arduino would have no trouble doing it.
15  Using Arduino / Programming Questions / Re: n00b problem, can't get analogRead to work on: April 07, 2014, 03:37:11 pm
The files on the Google drive are not public, or something.
Post the schematic and the code here on the forums.
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