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46  Community / Exhibition / Gallery / Re: Goal- CNC for less than $100 on: February 11, 2012, 07:55:10 pm
Hope you got your furnace fixed. Used to work on them for a living. Work for a manufacturer now. I know how much of a bind that can put you in. Can be expensive too.
47  Community / Exhibition / Gallery / Re: Goal- CNC for less than $100 on: February 10, 2012, 02:32:27 pm
I have personally built a cnc router and I think you may want to get some more threads per inch.  The 1/4 inch rod is probably appealing, but the 20 TPI will cause issues with travel times and weak torque on your motors.  The faster the stepper motor turns, the lower the torque it can provide.  I am currently looking into changing my rods to a more coarse thread for faster travel.

All of that being said, the goal is to keep the project under $100, so I understand if speed and torque are not of prime concern.
48  Community / Bar Sport / Re: Philosophical debate on language leads to question on: February 02, 2012, 11:50:30 am
@lefty--how true it is!
49  Topics / Home Automation and Networked Objects / Re: heating control with web interface on: February 01, 2012, 12:48:50 pm

I understand what you're saying about the temperature of the radiator feed water, but I think you could probably do it by using a PI loop to determine how much heat is required, rather than the outdoor temperature.  With a PI algorithm, you can decide how much heat to add by measuring how far you are from the desired temperature and how long you have not been at the desired temperature.  The outdoor temperature would affect how fast you drift from the desired temperature, but you would probably need to determine experimentally how much gain to add based on the outdoor temperature.  A PI would do this automatically, and without the need for the outdoor temp.  Food for thought.
50  Community / Bar Sport / Re: Philosophical debate on language leads to question on: February 01, 2012, 12:42:04 pm
The same is true in Aviation.  English is the spoken language for airlines.  Yes, there are people who are multi-lingual, but if you want to fly the big birds, you must speak English.
51  Topics / Home Automation and Networked Objects / Re: Home automation system - Let's begin... on: January 31, 2012, 01:58:58 pm
I'd suggest looking at this post:,8721.0.html
I finally got it working at my house this weekend.  The Apache server configs need some massaging to get it to work, but I can give you some details.  I have a password protected website with my Arduino remote control webpage behind the login.  My test setup was to put an LED on the Arduino and use the webpage to turn it on and off.  I plan to move toward controlling other things, like lights (lamps), possibly garage door, etc.  I don't know how to do any visible feedback on the webpage.  I may look into doing something like that as well, although it isn't my main concern.
52  Using Arduino / Sensors / Re: Fuel level sending unit on: August 08, 2011, 01:08:08 pm
There is one gauge that I might suggest.  There is a guy that used to write for kitplanes magazine and I saw this:

I think it's a very nice solution, AND, you won't have any chance of ignition if you follow their suggestion and coat the plates.  Have a look.
53  Using Arduino / Programming Questions / Re: How to require a key-up event before continuing on: July 08, 2011, 03:21:14 pm
You could use something like this to determine if the go button is not released.  Once the button is released, it changes the value of go_button_pressed.  When the value goes from 1 to 0, the program starts on your PC.

              if((go == LOW) && (last_go == LOW))
                     go_button_pressed = 1;

              if((go == HIGH) && (last_go == LOW))
                     go_button_pressed = 0;
54  Using Arduino / Programming Questions / Re: help with serial on: July 08, 2011, 02:56:17 pm
That did it!  I figured it was something simple.  Thanks guys.
55  Using Arduino / Programming Questions / help with serial on: July 08, 2011, 02:37:10 pm
I'm trying to get my arduino to respond to serial commands so that I can then progress toward implementing a remote control home automation-esque application later on.  The problem is that I can't get it to switch between states.  Can someone please review my code and give me some input?  I'm getting tripped up somewhere, but I'm not sure where.

int ledPin = 13;
int number_in = 0;
int state = 0;
#define BLINK   0
#define NO_BLINK   1

    void setup() {
      pinMode(ledPin, OUTPUT);

    void loop() {
      switch(state) {

        case BLINK:

           digitalWrite(ledPin, HIGH);
           digitalWrite(ledPin, LOW);
           if(number_in == 1)
                state = NO_BLINK;

        case NO_BLINK:

           digitalWrite(ledPin, LOW);
           if(number_in == 0)
                    state = BLINK;

    void readSerial() {
        if (Serial.available() > 0) {
          number_in =;
56  Using Arduino / Sensors / Re: Sensing tank fullness on: May 12, 2011, 03:45:41 pm
Personally, I like the solution provided by a kitplanes columnist.  See the following page:  In particular, see these three articles on capacitative fuel gauge (parts 1, 2, and 3):    and    and
57  Using Arduino / Interfacing w/ Software on the Computer / Re: Arduino behaving differently connected vs disconnected on: May 03, 2011, 11:55:13 am
Make sure your supply voltage from the batteries is high enough.  I have a duemilanove and it works fine from USB power, but if I connect to batteries, it behaves strangely if the voltage is less than 7 VDC.  I was using a 4 AA battery pack and it doesn't provide a high enough voltage for the board to operate properly.  With some peripherals it is okay and with others it isn't.  A 9 V battery works well for a short time -- not much capacity.  Try using a larger battery pack.
58  Forum 2005-2010 (read only) / Troubleshooting / Re: possible to random choose a value from an array? on: June 15, 2009, 09:54:15 pm
That works perfectly, see my work here:

Thanks for your help, AWOL.  I just needed to get over the hump.
59  Forum 2005-2010 (read only) / Troubleshooting / Re: possible to random choose a value from an array? on: June 12, 2009, 07:35:11 am
I looked at the Random() command pretty closely before asking.  The problem I was having was that the PWM outputs are not all sequential, so you can't give it a limited range and expect it to always "land on" one of the preferred outputs.  I did find another way, though.  I used the random number generator with a range limitation.  I then used IF statements to tell it that numbers 0-24 = output 1, 25-48 = output 2, etc.  That seems to be about as clean as I can get it.
60  Forum 2005-2010 (read only) / Troubleshooting / possible to random choose a value from an array? on: June 11, 2009, 12:51:17 pm
I am working on a firefly driver with my Arduino andI want to use the pwm outputs to drive the LEDs.  I plan to light only one LED at a time.  Since the PWM outputs are not all sequential, is it possible to use the Random() command to choose a value from an array?--each output pin would be a value in the array.  What's the best way to go about this?
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