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1  Using Arduino / Sensors / Re: Non-invasive LED watcher on: July 30, 2013, 08:43:32 pm
I tried using the photodiode of a Photo Interrupter but it did not work with colored LEDs. In fact, it only works with IR-LEDs.

I wonder about the pros and cons of using LDR vs phototransitor vs photodiode (one that senses non-IR LEDs).
2  Using Arduino / Sensors / Non-invasive LED watcher on: July 30, 2013, 10:28:26 am
I want to watch the LED of a piece of equipment. I can't open it (implies on loosing warranty). I'm seeking solutions to read this LED in a non-invasive way such as using LDR, Photodiode, etc. I've got no experience on this so any ideas and experience on this is welcome.

Extra question: I already have a photo reflective sensor (like this http://www.robotshop.com/productinfo.aspx?pc=RB-See-191&lang=en-US), can its photodiode be used to sense any colored LED?
3  Using Arduino / Project Guidance / Plug Arduino + Android + Power source via USB on: July 18, 2013, 01:26:42 pm
I have a set of monitors plugged to an arduino that talks over USB with an Android phone. My question is: how do I plug a external power source to keep the cell phone charged as well feed arduino board?
4  Using Arduino / Motors, Mechanics, and Power / Using 9v power supply with 6v servos on: August 15, 2012, 10:01:09 am
I'd like to use a 9v power supply to power up an arduino board and a bunch of servos. Servo input range is 4.8v to 6v. What's the recommended way of wiring these up? I thought of assembling a LM317 9v to 6v circuit. Is that overkill?
5  Using Arduino / LEDs and Multiplexing / Re: Reading chess board with reed switches on: August 10, 2012, 07:54:07 am
Hm... then sounds like the same amount of soldering trouble, but cheaper? I'm failing to see other benefits. I find soldering one reed switch to each diode and dealing with a single IC easier to do.

Thanks guys!
6  Using Arduino / LEDs and Multiplexing / Re: Reading chess board with reed switches on: August 10, 2012, 07:35:57 am
Got it. So, if I go with 8 74HC165's, will I need resistors? Sorry, I've got ask since I know little about interfacing.
7  Using Arduino / LEDs and Multiplexing / Re: Reading chess board with reed switches on: August 10, 2012, 05:49:47 am
Do see a simpler solution?

I could use the 595 only and read 8 cols with 8 pins. That would simplify things a bit.
8  Using Arduino / LEDs and Multiplexing / Re: Reading chess board with reed switches on: August 10, 2012, 05:24:55 am
Oops, i actually meant a 595 for rows and a 165 for cols.

Do i need resistors or can i just attach rows and columns directly? How do i wire this thing?
9  Using Arduino / LEDs and Multiplexing / Re: Reading chess board with reed switches on: August 09, 2012, 09:57:46 pm
A switch matrix plus two 165 will let me read whole board with 7 pins (3 for each 165 and 1 return pin).

I believe i can use two arduinos, 1 for reading board and controling an arm, and the other one for chess logic. We'll see.:-)
10  Using Arduino / LEDs and Multiplexing / Reading chess board with reed switches on: August 09, 2012, 10:57:18 am
I have this chess board and pieces with magnets on the bottom. My idea is to place a reed switch below each tile so that Arduino can detect movements by comparing boards before and after one movement.

How do I wire these reed switches to use as less IO pins as possible without using too much code (I need room for the chess logic)?
11  Using Arduino / Motors, Mechanics, and Power / Re: How to wire up unipolar stepper motor with L298N? on: May 21, 2011, 03:58:49 pm
I now remeber I bought this board to use with a bipolar mottor. I just noticed I'll need to control a unipolar motor though. :/

GedgetShield does not really fit the porpuse in my case -  I need a more specialized piece of hardware, just like that board I pointed out as I'm going to deploy it in a dedicated machine. Recomendations?

Side question: I read a blog post (sorry, cannot find reference anymore) one may use a unipolar stepper as a bipolar one. What are the pros and cons of doing so?
12  Using Arduino / Motors, Mechanics, and Power / How to wire up unipolar stepper motor with L298N? on: May 21, 2011, 01:16:34 pm
I'd like to control a unipolar stepper motor through L298N. I've this board http://www.seeedstudio.com/depot/l298-dual-hbridge-motor-driver-p-284.html. How do I hook them up?
13  Using Arduino / Motors, Mechanics, and Power / Where can I buy arduino friendly solenoid valves? on: May 12, 2011, 11:41:28 pm
I found incredibly hard to find online stores which sell fluid related hardware. I'm designing a filling machine and I need solenoid valve to let me select between filling sources. I was wondering whether there exist pololu-like store for fluid related hardware but I could not find any. Suggestions?
14  Forum 2005-2010 (read only) / Syntax & Programs / Re: Can't create patterns with 74HC595 on: January 15, 2010, 06:15:47 am
Argh! My bad! I just learned how my breadboard works. Sorry.
15  Forum 2005-2010 (read only) / Syntax & Programs / Re: Can't create patterns with 74HC595 on: January 14, 2010, 10:46:13 pm
I wrote my own version of shift out based on what I understood from the datasheet but I'm still cannot create patterns.

Do you see anything wrong with the following code?

Code:
int RCLK = 8;
int SRCLK = 12;
int SER = 11;

void setup() {
  pinMode(RCLK, OUTPUT);
  pinMode(SRCLK, OUTPUT);
  pinMode(SER, OUTPUT);
}

void loop() {
  digitalWrite(RCLK, LOW);
  digitalWrite(SRCLK, LOW);
  digitalWrite(SER, LOW);
  for (int i = 0; i < 256; ++i) {
    digitalWrite(RCLK, LOW);
    for (byte j = 0; j < 7; ++j) {
      if (i & (1 << (7-j))) {
        digitalWrite(SER, HIGH);
      } else {
        digitalWrite(SER, LOW);
      }
      digitalWrite(SRCLK, HIGH);
      digitalWrite(SRCLK, LOW);
    }
    digitalWrite(RCLK, HIGH);
    delay(1000);
  }
}
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