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1  Using Arduino / Project Guidance / Re: Magnetometer Accelerometer project question on: May 09, 2013, 03:18:44 pm
Erdin,

Thanks for the reply.  I don't really care to deteremine the position of the magnet.  The number one requirement is whether the magnet is in the box (say dimensions of 10cm by 10cm by 10cm).  So if the strength of the magnet overwhelms the sensor's sensitivity it is not an issue as long as the I can tell of the magnet was sensed.

If I could get direction of the pole or a reading of the gaussian value, well that is icing on the cake. 

Tim
2  Using Arduino / Project Guidance / Magnetometer Accelerometer project question on: May 09, 2013, 01:48:02 pm
I want to build a small wooden box that I can place an object into.  The object will be magnetic (a strong rare earth magnet will be affixed to the inside of the object).  The bottom of the box contains an accelermeter/magnetometer sensor package.  I would like the box to determine:

* If the magnetic object was placed inside of the box
* Orientation of the box
* If possible, I would like to be able to tell one magnetic object from another (ie, based on the gaussian signiture of the object)
* If possible, the polar orientation of the object containing the object

There are several accelermeter/magnetometer sensor packages available...any recommendations that would meet my needs?

Thanks!

Tim
3  Using Arduino / LEDs and Multiplexing / Re: Source cheap RGB LED connectors (or 4 pin connectors) on: August 07, 2011, 09:41:44 pm
Quote
The ultimate connector would allow me to connect and disconnect the LED and could be extended to 24 inches.
Not necessarily, extending high speed logic signals over lengths of wires is not always easy.

I am not sure why you want sockets anyway, it's only four pins and a quick dab with a soldering iron will suffice.

This is sort of an art project (actually a magician's prop for a children's routine).  I want to construct a little tree about 24" tall and place LEDs in the branches and do some pretty color sweeps and chase sequences.  Therefore the wires may be up to 24" long between the PCB and the LEDs.  I thought it might be convenient to run the wires through the tree and be able to connect and disconnect.  Is that length going to be a problem? 

As a complete noob to this electronics, I'm guessing that the best set up might be to solder 4 - 24" wires to the LED leads and place a 3 pin connect on the RGB leads.  This a single pin connector to the common cathode.  I imagined that I would solder on a 16 pin header for each TLC5940 and a separate header with enough pins for cathode leads.  Any guidance would be most appreciated!

Thanks,

Tim



4  Using Arduino / LEDs and Multiplexing / Re: TLC5940 Flickering on: August 07, 2011, 09:15:51 pm
I suspect you have no decoupling capacitors on the TLC5940s.
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Thanks Mike.  I'm an electronics beginner so some of your tutorial was over my head but I think I got a rough understanding.  So the VCC and GRD on are pins 21 and 22 on the TLC5940NT.  Would I run a 0.1 µF capacitor between those two pins on each IC, correct?

5  Using Arduino / LEDs and Multiplexing / Re: TLC5940 Flickering on: August 07, 2011, 08:48:16 pm
How long are the connections between the tlc's?

Also, which tlc's are the ones flickering? The last two on the chain or is it random?

Four TLCs altogether.  Usually happens on the 2nd and or 3rd TLC.  Connections are about 3 inch jumpers. 
6  Using Arduino / LEDs and Multiplexing / TLC5940 Flickering on: August 06, 2011, 11:42:24 am
First, I'm an electronics noobie.  I've daisy chained 4 TLC5940s on a breadboard exactly as shown on the Arduino TLC5940 Library page and a total of 21 RGB LEDs.  One diversion from that setup is that I used a 2.2K resistors instead of 2K resistors (my local Radio Shack didn't have 2K resistors).

It works pretty well expect that sometimes one or two of the TLC5490s flickers it's LEDs. Any ideas?

Thanks! 
7  Using Arduino / LEDs and Multiplexing / Source cheap RGB LED connectors (or 4 pin connectors) on: August 06, 2011, 11:23:56 am
I'm looking for a source to buy cheap 4 pin connectors for 5mm RGB LEDs.  I've found some sources for RGB LEDs but the prices are crazy expensive at $4-6 per connector. 

I'm thinking that some kind of 4 pin connector would work just fine but I'm not sure what to buy.

The ultimate connector would allow me to connect and disconnect the LED and could be extended to 24 inches.

Thanks!

8  Using Arduino / LEDs and Multiplexing / Re: TLC5940NT not working? on: July 22, 2011, 01:51:45 pm
I just hooked up my 5940 a few nights ago and it works great!  Really easy to use with the library.  My project is not a matrix so this chip is just right for me.  Have you thought about just getting some new common anode LEDs?  I just bought 50 RGB LEDs from c-leds.com for under $20.  They even threw in a four extra LEDs and shipping was very fast. 

Tim
9  Using Arduino / Project Guidance / Re: Independently control 25 RGB LEDs on: July 14, 2011, 12:44:48 am
If you're after a shield rather than soldering practice, there are lots of options for you.  iTead has an 8x8 matrix color shield that is reasonably priced that should be more than capable of driving your project (http://iteadstudio.com/store/index.php?main_page=product_info&cPath=18&products_id=312&zenid=g9r1efj1n3iqt5pct82qam11k0).  This shield will give you independent control for up to 64 individual RGB LEDs with PWM control.

That shield looks great but can you really independently control 64 RGB LEDs?  There doesn't seem to be enough pins!  Or is this some sort of multiplexing scheme that share color information between neighboring LEDs?  Keep in mind that I am not building a matrix or a cube.  The design would be 25-30 LEDs that appear to be randomly placed in a model tree (kinda like independent RGB lights on a little Christmas tree). 


 
10  Using Arduino / Project Guidance / Re: Independently control 25 RGB LEDs on: July 13, 2011, 01:26:59 pm
Correct Bilbo - I was hoping for way to be more efficient with less pins (via code) but it sounds like "as many TLC5940s as needed" is the best approach.  Or I was hoping for a pre-existing shield with that many PWM outputs.

Thanks for the input.
11  Using Arduino / Project Guidance / Independently control 25 RGB LEDs on: July 13, 2011, 11:42:46 am
First, I'm an Arduino noob although I am getting comfortable with many concepts.  I have excellent C programming skills but minimal electronics skills.  I need some help assessing a project.  My project is a lighting a small scale fake tree (24 inches tall) with between 25 and 30 LEDs that will be animated in a number of patterns (twinkling, chases, etc.) so independently controlling the LEDs is a must.

I would like to use RGB LEDs.  However, I could get by with bi-color LEDs.  I would prefer PWM the LEDs for fading effects if feasible. 

I guess one question is whether there are ways to independently control RGB LEDs with less than 3 pins per LED.  Such as pulsing the color information on three pins to multiple LEDs and control the cathode to light the correct LED (I'm thinking like how an interlaced computer display draws every other line).

Is there a shield that would allow me to control 25-30 RGB LEDs independently?

Any ideas would be helpful.   

Thanks!
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