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16  Using Arduino / LEDs and Multiplexing / Re: 1 Arduino with 6 Neo_Pixel60 on: October 11, 2013, 02:13:17 pm
I'd recommend using a Teensy 3.0 instead. The OctoWS2811 library will drive 8 strips at the same time.
17  Using Arduino / Programming Questions / Re: problems with ds1307 and arduino uno on: October 10, 2013, 03:48:39 am
Perhaps this is a hardware problem? Are you sure that your DS1307 has power, the correct crystal, is running, has I2C pullup resistors, etc?
18  Community / Website and Forum / Re: Bullets not working on: October 10, 2013, 03:26:42 am
This is confirmed, annoying, and needs to be fixed. Bullet points (lists) are a great organizational tool.
19  Using Arduino / LEDs and Multiplexing / Re: Help on: October 10, 2013, 03:21:05 am
Could your question be phrased as below?

Quote
I need 3.3V at 3A, and have a 12V/3A power supply. I have some fixed-voltage 3.3V/1A linear regulators. Can I put them in parallel and get up to 3A at 3.3V from the combination?

If so, then it's highly unlikely. The first problem is that your regulators will not output exactly the same voltage; whichever one has the lowest voltage (even a small amount is enough) will attempt to supply all of the required 3A current. It will overheat and fail quickly.

The second problem is that your regulators are rated for 3.3V/1A under great conditions. First, that they don't have to dissipate too much power, and second that they are heatsinked enough to keep them near room temperature. It's unlikely that you'd even achieve 3.3V/1A from the top circuit. Your regulator will attempt to burn off (12V-3.3V) * 1A = 8.7 watts as heat. In a SOT-223, that's a lot of heat to get rid of somehow. If you look in the datasheet, you should find a table or graph that indicates what current ratings are possible at various junction temperatures. And you should also find a case dissipation rating (degrees per watt) that will help you find the difference between ambient temperature (what your heatsink can manage) and junction temperature at a given amount of dissipated watts. Then, if you're specifying a heatsink, you'll need to find out how many watts it can transfer to the air depending on various ambient temperatures.

Sound like a tough problem? It is...it's an engineering problem, not just plugging parts together and expecting them to work. You can significantly reduce the amount of risk/worry by choosing a different regulation solution:

* Find a premade regulated power supply with the desired amperage. Everything is already handled for you.

* Change the power supply to 3.3V + regulator overhead and not much else, and use a linear regulator that can supply at least 3.3V. This will greatly reduce the amount of heat dissipated from the regulator.

* Instead of linear regulators, choose a switching buck regulator design. This will have much greater efficiency, so not only is heat not a big problem, but you also aren't uselessly wasting twice the power your circuit actually needs. There are simple switching regulator designs like the LM2576 that don't require many external parts.

* Find a premade switching step-down regulator board or DC-DC converter that can supply the voltage and current you need.
20  Using Arduino / LEDs and Multiplexing / Re: Problem with ShiftPWM and RGB LEDs on: October 10, 2013, 02:46:17 am
How are you connecting the bench power supply to your circuit? Specifically...what exact pins on which parts of the circuit and Arduino are you connecting to the bench supply?
21  Using Arduino / Project Guidance / Re: USB extender on: April 24, 2013, 01:27:45 am
No. Just buy your extremely cheap and long distance USB extender: http://www.monoprice.com/products/subdepartment.asp?c_id=102&cp_id=10303&cs_id=1030312

They have HDMI ones too http://www.monoprice.com/products/subdepartment.asp?c_id=109&cp_id=10110&cs_id=1011012
22  Using Arduino / Project Guidance / Re: Advice for building a laser receiver grid on: April 23, 2013, 08:13:20 pm
So...what is this "time it took" you intend to measure? I hope you're not trying to measure time-of-flight of a laser pulse with an Arduino.
23  Using Arduino / Project Guidance / Re: Help please! I need to make a butterfly! on: April 22, 2013, 12:39:37 am
Muscle wire would be cool, but just a little tricky. Probably the easiest way is to mount this thing on a vertical tube, which is in turn mounted to a base containing the electronics. The wings are mounted to a yoke arrangement as shown in zoomkat's post, and a wire would run down to a small RC servo mounted in the base. Same idea as those robot grabber sticks.
24  Using Arduino / Project Guidance / Re: Garbage reading from Chronodot 2nd time around?? on: April 21, 2013, 11:47:43 pm
None of this should be happening. By any chance are you trying to run the LED displays from the Arduino's regulated 5V?
25  Using Arduino / Programming Questions / Re: Displaying time on LCD with ChronoDot 2 on: April 18, 2013, 05:46:26 pm
I don't see the same value, I see it setting register address 3 for the get_date function, and register address 0 for the get_time function.
26  Using Arduino / Programming Questions / Re: Displaying time on LCD with ChronoDot 2 on: April 18, 2013, 04:31:36 pm
The requestFrom lines are correct because immediately prior to the day/month etc request, the starting address register is written to the device.
27  Using Arduino / Project Guidance / Re: PCB has tracks on wrong side? what happened? on: April 08, 2013, 08:15:56 pm
Are the pads somehow not on the bottom? Because with a "single sided" board (which seeedstudio doesn't normally do), it doesn't matter what side the traces are on if the pads are actually double sided and through plated. The circuit is the same. If you actually only sent one copper layer file, then yeah...one side would be missing the pads.
28  Using Arduino / LEDs and Multiplexing / Re: Arduino MEGA powering 50 RGB LED's on: April 03, 2013, 07:56:35 pm
Yes, ElcoJacobs ShiftPWM is nicely done!

I won't have the high density WS2811 in stock for while. Still have the 30px/m and the 60px/m in waterproof (possible to just slide the strip out of the sleeve). I think several other vendors have it, too.
29  Using Arduino / LEDs and Multiplexing / Re: Arduino MEGA powering 50 RGB LED's on: April 03, 2013, 12:07:22 am
It depends how far apart you want the columns to be. If you can't use 32mm spacing or 16mm spacing, then the WS2811 strips won't work without a lot of cutting and rewiring (which wouldn't be too bad for only 60 pixels). It'll probably actually be easier to control all the RGB LEDs individually rather than trying to have groups of three controlled together...such is the state of available pixels strings and strips these days.
30  Using Arduino / LEDs and Multiplexing / Re: Arduino MEGA powering 50 RGB LED's on: April 02, 2013, 11:02:56 pm
Attitude, Google, 150 wires...let's throw all that out.

The main piece missing here is how you want to arrange these LEDs. How bright are they, should they be clusters or single LEDs, how far apart should each pixel be, how bright, etc.

Trying to control 150 wires' worth of PWM is not the best approach here. You need smart pixels, which come in a wide range of types. They will communicate down a single chain of wires using a serial communication protocol. You can actually just buy premade pixel strings with 25 or 50 pixels on a wire, spaced 4" apart. Look for WS2801, WS2811, etc. I also sell LED stuff like the ShiftBrite which is more modular as you chain them together with pluggable cables. The WS2811 strips are also really great because they are really cheap and you can cut them up and rewire as needed.
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