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46  Using Arduino / Project Guidance / Re: New Project Quick Question. Need Help. on: May 27, 2013, 03:02:23 pm
What would I need to be able to use 5 Flex sensors and 5 stepper motors? I have the arduino uno. Do I need a mega? Thank you.

What are the specs of the steppers? How do you plan driving them? Directly or through an IC like the L293 or L298 (the most common) ?

I strongly advise on not using direct drive for the steppers. Even if they are low power, it is often best to use a motor driver IC.

If you choose to use a driver, you don't need a Mega. Instead, you'll need 5 driver ICs + 3 x 74HC595. That is much cheaper than buying a Mega, and you'll save a lot of pins in your arduino. You can drive all those steppers with only 3 pins.
47  Using Arduino / Installation & Troubleshooting / Re: Micro ICSP header pins should be optional on: May 27, 2013, 12:57:40 pm
"gee, we need a girls with a desoldering gun in the
production line."

I wouldn't use a Mini as part of a product with high enough volume to justify a "production line". In that case, I'd rather roll my own board, including other components and parts the Mini will be connected to, have it manufactured and assembled in China, and profit from the much lower costs of parts and production.

Most so-called industries today are nothing but a small office with a phone line and fast internet, with production outsourced to China. These industries only handle reseach & development, some marketing and sales to the resellers or end-users. Many 1-man business are like that. Some of them don't even have or need a warehouse.
48  Using Arduino / Installation & Troubleshooting / Re: Micro ICSP header pins should be optional on: May 27, 2013, 12:07:28 pm
either have to roll your own, or squeeze hard, or snip headers. Ugh.

With a solder sucker and a soldering you can remove the header pins in less than 2 minutes, and still save the header for use in another project. It's even faster if you got some hot air gun or, in my case, a Dremel Versatip in hot air mode.

OTOH, I agree that there should be another standard for a smaller ICSP header. We have 4 or 5 standards for USB connectors, so a standard for a smaller ICSP header wouldn't hurt. Keep in mind that the ICSP headers we have in our Arduinos is already the small, 6-pin header. The usual header other MCUs use is a 10-pin header.

Like some wise man once said: the beauty of standards is that you can have many of them.
49  Community / Bar Sport / Re: Google Code is about to die. ( for a lot of us anyway ) on: May 26, 2013, 04:52:02 pm
SourceForge has turned into a nightmare.  Earlier this week it took half-a-dozen attempts to download WinAVR.  The pop-ups and redirects sometimes make it impossible to navigate.

Agreed. Specially if you`re trying to download files from mobile browsers, even if it is Chrome on Android. It just doesn`t work as it should.
50  Using Arduino / General Electronics / Re: Bigger power supply on: May 24, 2013, 11:02:54 pm

Finally, I moved on to a power supply with bigger capacity, i.e. 12V 30A .  I'm just wondering.  How far the damage would be if I accidentally shock myself with the 12V 30A output?  ( Sorry for asking newbie questions )


It is the current that kills, not the voltage. 30A is much more than enough to kill a person, specially given the proper conditions.

One proper condition would be your hands wet and each hand grabbing one of the poles of the PSU. That current would go from one hand to the other, passing through your heart and killing you.
51  Using Arduino / Project Guidance / Re: What type of sensor to detect my cat on my porch? on: May 24, 2013, 10:18:41 pm
Only if you didn't know where it was, then you could say it both inside and outside.
You can never know, for certain, where Schrödinger's cat is.

That is Heisenberg's cat.
52  Using Arduino / General Electronics / Re: How Often do Electronic Components Stop Working? on: May 24, 2013, 05:30:45 pm
Actually there are loads of these things and a guaranteed unknown amount more if the Incompleteness Theorem is right. And that's a good thing since it means science will never be done if that's true.

Amen to that.

The right side people (in the scale), like Physicists, Chemists, Biologist, Astronomers, etc are all in accordance that science is an evolving thing, that there are more questions to be made than answers already found. Most of these people call what they do science rather than a profession. My wife, for example, has a PhD in cellular biology and has just started her post-doctorate in odontology. She calls herself a scientist, not a dentist.

To the left of the scale, the more applied people, can be divided into 2 categories: those that consider it a profession and those very few that consider it a science. The professionals usually think that their knowledge is an already evovled thing, that whatever there is to know has already been written. I know SEVERAL medics/doctors that are like that. They refuse to acknowledge that medicine is a science as well, and are more likely to think that everything they need to know, now and in 50 years, is already in the books. The same goes for several psychologists, sociologists, etc.

To a certain extent, we can also call religion a science (I am intentionally not using the word teology), because whatever faith we follow, how we deal with it has changed over the last hundred of years, at least in the western religions. We aren`t as tight ass about religion as out ancestors were 100-200 or 300 years ago. People in Massachussets don't hunt witches anymore. The Pope doesn't have that much influence in governments. Only recently some churches (as in "institutions") have acknowledged that our relation to whatever Superior Being we believe in has changed.

53  Using Arduino / Project Guidance / Re: What type of sensor to detect my cat on my porch? on: May 24, 2013, 12:08:59 pm
A dog makes a good sensor.

I was about to post the same thing.

If the cat is Schrödinger's cat, you may need a Geiger Counter. Fortunately, there is already a shield for that.

54  Using Arduino / General Electronics / Re: How Often do Electronic Components Stop Working? on: May 24, 2013, 09:32:50 am
Electronics is Math.

Isn't mostly everything?

55  Community / Bar Sport / Re: Ban Fritzing on: May 24, 2013, 09:27:54 am
Some forum user ask why they do not step up to the next level (Eagle). You already wrote the answer:

because I haven't had the time to tackle Eagle yet

My 2 cents:
The next level isn't Eagle, but some easier to learn package, like DipTrace. I learned DipTrace fairly quick, and currently I feel absolutely no need to invest (more) time learning Eagle.

By more time, I mean that I have tried to learn Eagle, only to find it counter-intuitive to use. I know it is extremely powerful and capable of doing a few things I still don't know how to do in DipTrace, but, neverthless, for someone to has electronics just as a hobby, DipTrace is more than enough. Even for most students, DipTrace will suffice.

What I REALLY miss, however, is an updated version of something like Electronics Workbench, which I used a lot back in college (in the 90s). I never took the time to learn SPICE. Too bad that NI's Multisim is too expensive.

56  Using Arduino / Project Guidance / Re: Fan Controller for Computers on: May 24, 2013, 07:57:58 am
So to start out you have a fan header on a motherboard which through its own software will regulate the voltage coming out of the line and defaults at 12V.

Not necessarily. The 4-pin fans will not variate voltage. Instead it will have a PWM signal in the 4th pin, that is basically a really fast turn-on/turn-off signal. That will make the fan's speed vary.
57  Using Arduino / General Electronics / Re: My "where do babies come from?" of electronics. on: May 24, 2013, 07:53:18 am
117  leds give or take. connected a 9v with no resistors and they all lit up nice and bright. I don't know what I learned but I like it.

If your 9V source wasn't a battery (that has a very limited current capacity), but instead was a bench supply, a wall wart or any other source of AC-DC adapter, you'd have learned what it means to divide V/R when R=0: you get inifinite current (well, not infinite, but very high). All of your leds would give a very bright glow, right before exploding or simply dying. If your LEDs had held the high current (very unlikely), you might have had a blown fuse in the power supply.

So you learned that 9V batteries have an internal resistance that limits its maximum current.
58  Community / Gigs and Collaborations / Re: 7 segment display panels for diesel motors on: May 24, 2013, 07:28:49 am
Graynomad, thank you, mate! +1 karma for you!

I'll tell you why:
I have developed a patent-pending product that uses 10x MAX7219. The problem is that the MAX7219 is VERY expensive (even when bought in thousands). Until yesterday, I had no idea that there were direct replacements for it, until you posted about the AS1108. I went on to learn more about AMS and the AS11xx series and I found an IC that is a direct replacement for the MAX7219, the AS1100, and it costs less than half the price of the Maxim IC.

I had been looking high and low for that, and thanks to this thread and this post I found it. I've ordered a few samples from AMS and I'll report back when I get them and test them.

Thank you very much once more.


I've bough stuff from DX for a long time and never had trouble with them. Actually most of the arduino-related stuff I have is from DX. They are that cheap. The only downside is that packages from them take forever to arrive, with a 30-35 days delivery time being quite normal.

Another suggestion I make to you is products based on the TM1638, specially this one. It has 8x 7segs + 8 bi-color leds + 8 buttons, everything controlled by a single TM1638, for which there are very good, working libraries for Arduino.

59  Community / Bar Sport / An inspiring new view of reCAPTCHAs on: May 24, 2013, 07:15:43 am
Recently I got an entirely new, inspiring, view of what reCAPTCHAs really are, after watching the TED Talk below:

Luis von Ahn: Massive-scale online collaboration

Until then, I used to find CAPTCHAs a real PITA, an annoyance. Now I find them inspiring, and the tecnology behind it to be awesome. I am so amazed with it that I felt like sharing that with you.

I won't spoil the surprise... please watch the video above and we'll talk after the break.

One thing is sure: I'll never fell annoyed by reCAPTCHAs again!
60  Development / Other Software Development / Re: Atmega328p Programming from Uno on: May 22, 2013, 01:48:49 pm
It seems like you have a 328-PU (normal power) and NOT a 328P-PU (low power);

They have different signatures, and that seems to be the root of your problems.

Open avrdude.conf, look for the 328P-PU signature and change it to match the 328-PU.

I don't have the Arduino IDE installed in the computer I am using right now, otherwise I could tell you exactly what line to change. With a 30 seconds search on these forums, you'll be able to do that, 'though.
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