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5836  Using Arduino / General Electronics / Re: Electronics Newbie, Programming Professional on: April 04, 2011, 12:48:31 pm
Here is a tutorial of how to hook up an LED:

http://arduino.cc/en/Tutorial/Blink

Very basic stuff but once you master it, you can expend it to several LEDs blinking in certain sequence. If you need a couple dozen of LEDs, you will likely construct an LED matrix and address them by row and column (only one turns on at a time in this scenario) or use shift registers to control more than a couple dozen of them:

http://www.arduino.cc/en/Tutorial/ShiftOut

If you get more comfortable and want to do more, say swing the handbag and show a persistence of vision image, read this:

http://liudr.wordpress.com/2011/04/03/persistence-of-vision-2/
5837  Using Arduino / Programming Questions / Re: no idea on arduino language. Any help appreciated on: April 03, 2011, 11:33:38 pm
Come back with some actual code you write with questions now.  smiley-grin
5838  Using Arduino / General Electronics / Re: what temp sensor do i have? on: April 03, 2011, 11:27:46 pm
First of all, a thermistor costs like $0.40 a piece if you buy 10 or 20 at a time so even if you can't figure out the factors, not big deal, buy some that come with spec sheets. If you want to determine the spec of your blue thermistor, you need to measure at least two temperatures., 25DegC and something like 80DegC if it's not too hard to do.

Set 25DegC and measure resistance gives you R1, then set at say 85DegC and measure resistance again you can solve for B.

Here is my article on how to use a thermistor:

http://liudr.wordpress.com/2011/02/10/measure-temperature/
5839  Using Arduino / Sensors / Re: How to reduce the measuring range of a TMP36 on: April 03, 2011, 11:03:21 pm
That's the typical problem with ratiometric sensors running from long wires. If you used a bare thermistor, like a 10K NTC thermistor ($0.40), you will have much less problem especially if you're measuring a small temperature range. You can always find the right serial resistor to get best accuracy.

If you insist on using the TMP36, could you use heavy gauge (thick) wires for all three connections? If you have like RJ45 wire, use more pairs to carry 5V, GND, and signal can also reduce your error.

Oh, in case you want to switch to thermistor, here is an article about how to:

http://liudr.wordpress.com/2011/02/10/measure-temperature/
5840  Using Arduino / Sensors / Re: Triggernig a camera by a sonar, what's the right camera? on: April 03, 2011, 10:57:57 pm
I think Terry King has a project with camera triggered maybe by photo gates. Hope he's around to answer this question.  smiley
5841  Using Arduino / Sensors / Re: ds1307 loosing 20min/day? on: April 03, 2011, 10:56:18 pm
cyberteque,

I remember my 486 being inaccurate with time. That's probably what you see on your older systems (you mentioned in a separate post your P100). I didn't have AC back then but I didn't correlate temperature with time shift. So is a more recent computer (say 3 year old) equipped with a crystal with temperature sensor or compensation then?
5842  Development / Other Software Development / Re: Anyone else developing a user interface (UI) on LCDs and keypads/buttons? on: April 03, 2011, 12:08:53 pm
Good idea!

Right now my phi_prompt select_list() will take a list from PROGMEM and display it according to the parameters in the structure and interacts with the user (up button is next item, down is prev) until the user hits left, right, enter, or escape. So one function call then the return is final decision of the user.

The left and right buttons can be used in a larger display or just 16X2 to navigate between selections much like a dialog box with tab keys in Windows. Say you change one number and press left, you can change the previous field and right a few times to change another field. I have not implement that into an actual function of dialog box (including several interactive lists and number entries) but I'm already using the basic blocks in my clock adjustments:

I will just add a function that sets up a user interface like a dialog!

5843  Using Arduino / Project Guidance / Re: Propeller clock with arduino on: April 03, 2011, 10:32:52 am
There is a sensor (typically Hall Effect magnetic switch or photogate) on the rotating board to sense where to start displaying. You have to display the same message at the same spot several times a second to get persistence of vision. Speed of the rotation is calculated by the rotating board, using time difference between two subsequent sensor readings. It's like if there was 250 ms of time between subsequent triggers from the sensor, the speed is 1/250ms=4Rev/s
5844  Using Arduino / Project Guidance / Re: Multiple buttons on: April 02, 2011, 11:46:57 pm
Are you sure you mean buttons or three twist knobs (potentiometers)? Describe your user interface to us in more detail.
5845  Using Arduino / Project Guidance / Re: Propeller clock with arduino on: April 02, 2011, 11:43:40 pm
Welcome to the forum. That clock seems difficult requiring both electrical and mechanical skills. If you want something easier to do, maybe buy a POV thingy from adafruit. BTW, I also have my own POV clock stuff. Here is a link to my gadgets. Look in the middle of the page.

http://liudr.wordpress.com/gadget/

I do warn you that improperly secured hardware on a rotation platform is dangerous.
5846  Topics / Education and Teaching / Re: What's your opinion on spending $50 on your kids education? on: April 02, 2011, 11:04:57 pm
cr0sh,

I bet your parents were very good parents. I also owe mine a lot. My dad was a professor in electron science but he didn't really teach me electronics. We didn't spend much time together because he spent countless time in his lab. The first time I felt interest in electronics was right after I finished a gruesome task of teaching 3xx-level electronics for physics majors. It seems that physicists don't like to either teach or do electronics. When anything gets too practical, it's out the physics door. I owe partly of my employment to saying "oh yes, I am certainly willing to teach electronics" during interview smiley-mr-green

Keff, I was intimidated by bare electronics parts as well, also the mentioning of designing PCB, or manufacturing hundreds of them. But all those were history now.

I think what helped me are three things: I have some money to buy parts (wouldn't work if I were half my age), I stumbled into the Arduino world with such a lively and helpful online community, my background in programming. As a physics major like most other physics majors, I only took one class in electronics in my junior year and that was it. Even after I taught the class, I still wasn't very interested in it. Until one time I came up with an idea that will be a teaching equipment. I used all my knowledge and couldn't figure out how to make it work. A very haphazard chance made me meet an artist, artist everyone! He was using arduino and he showed me what he did with arduino. After that I read about arduino and made the purchase. Eventually I made that teaching design work. It's not very good-looking but it's showed me the potential of arduino. I've been a fan since that time (around 2009). With my programming background, all I needed are ideas and time. The rest was just hard labor smiley

So looks like many are interested in this topic. We should certainly chat often on this board. I think I've got like 1000% what I was expecting when I started this post  smiley-lol smiley-lol smiley-lol Thanks to you all!
5847  Topics / Education and Teaching / Re: What's your opinion on spending $50 on your kids education? on: April 02, 2011, 10:45:30 pm
I would change some of the items, and the prices are a bit off. 
1 new video game = $60
1 month of cable TV = $50

mp3 players aren't positive or negative, everybody listens to music on the car radio
I would also leave books out in order to make a stronger argument. 

If I were writing a letter to parents I would explain all about how amazing microcontrollers are and what can be done with them.  Then explain how cheap these are compared to 10 years ago, and make the price comparisons at the end. 

Big oil, I like your point of just comparing prices without necessarily pointing fingers. Thank you.
5848  Topics / Education and Teaching / Re: What's your opinion on spending $50 on your kids education? on: April 02, 2011, 10:44:16 pm
One other thing I thought of... Who's going to help the absolute beginner ?

One can of course ask questions on this forum, I must say support in general is great,
but answers can sometimes also be a little intimidating...


Yes yes. But imagine asking a stranger questions and expect getting help. I still prefer asking here smiley
I'm trying to train teachers (high school) so they themselves are not absolute beginners but their students ARE! I'm training the teachers since I'm not certified to train kids, nor do I have the skills! Kudos to high school teachers! It's difficult job and doesn't pay much. I'm hoping with arduino they can do their jobs better, and kids enjoy more.
5849  Topics / Education and Teaching / Re: What's your opinion on spending $50 on your kids education? on: April 02, 2011, 10:40:41 pm
Quote
A mobile music platform only distracts the user and damage their hearings.
On the whole I have to agree but I think when students get to the age where they might want to be motivated by arduino, I would suggest that there are many who would understand the benefits of music. I personally listen to music quite a lot (obviously not at the volume level many kids listen to it at) but it can really make a difference in how you feel/how productive you are. So music in moderation (whether a portable device or not) can have major benefits.

On another note, I saw an elderly lady on a bus I was travelling on the other day listening to an ipod. You could tell she was happy listening to whatever it was and it was improving her mood. Travelling around on buses by yourself doesn't normally do good things to people's moods.

Thanks mowcius! That's good point. I agree. Just last Friday I used an old MP3 player, an npn transistor, and a few spare parts, made an old-school boom-box (not very boom-ie no box either). Just in time for my Electronics class lab on npn common-emitter circuit.

I think if I say arduino + mp3 or arduino + game device (maybe wii controller) = much more awesome maybe someone will buy my argument.
5850  Community / Bar Sport / Re: Sink or what? on: April 02, 2011, 12:22:56 pm
2B || !2B = 0xFF

 smiley-lol smiley-lol smiley-lol
Boolean algebra
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