Except there are two other important points there: distilled water and a calibrated reference thermometer.

Anyway, whatever, this is detracting from the OP's need to understand that at temperatures available to the man in the street, ie water up to about 100C, his thermocouple is unlikely to register on an Arduino pin because the voltage is below one unit.

If I ware u, I will test at 100 °C boiled water which is at least I don't need calibrate thermometer.

Not true.... water only boils at 100C at 1bar... I live at 1800m (6000') ASL and water here boils at about 94.

Did you see the chart I enclosed?

Yes of course, and I wondered why you said you use 100C boiled water when you are unlikely to have that. Even if you know the elevation, as you say the impurities and so on make a difference, so even at a known elevation, you will not know the temperature of boiling water without a thermometer. You can't calibrate anything that way since you don't actually know the temperature: even with the same water at the same place, on two different days with different weather and therefore barometric pressures, the water will boil at different temperatures.

If I ware u, I will test at 100 °C boiled water which is at least I don't need calibrate thermometer.

Not true.... water only boils at 100C at 1bar... I live at 1800m (6000') ASL and water here boils at about 94.

GND and VCC should be connected to the power supply for the motor, which typically won't should never  be the same one powering the Arduino.

.... but yep that's the way it seems to me that it works.

That is a Premier League heatsink eh?

And I'm wondering what would happen if I run 2 servos without an external power supply? Will they get damaged?

No... the Arduino will, because it will probably be called on to deliver more current than it should.

But wait a moment... if you're using the standard sweep program, that will be reversing direction at the end of each traverse and be going from 0 to 180 to 0 all the time.

Are you using standard servos or servos modified for continuous rotation? It wouldn't make sense to use standard servos for driving a robot, so presumably they are continuous? In which case, sweep will have the motors accelerating, decelerating, changing direction, accelerating in the new direction, decelerating etc etc.

The resolution of an Ardunio analog pin is 5V / 1023 steps, or about 5mV per step.

You didn't say what temp you're reading, but according to this graph , no type of thermocouple will provide anywhere near 5mV at ambient and some not even at boiling water temp, so I doubt if you're approaching an analog read value of 1.

Edit... what voltage did you actually read with your meter?

I cut and paste the code you posted, hooked up an HXT900 servo ala the "knob" circuit and it worked as advertised. There is nothing wrong with the code which must have been used a zillion times by now. I use a modified version of that very sketch to run two servos with a 2-pot joystick: no problems.

I don't know what servo comes with the kit though: it might be that it needs more current than the Arduino is happy to supply. Maybe try hook it up with its own power supply, ala attached pic? Edit.... quite a lot of servo "funnies" like disobedience and the shakes can be corrected by a better power supply: so it's a common thing to sort out soon as you experience a problem. If nothing else, it eliminates one possible source of the problem, and who knows, often it fixes it.... (Although it's strange in your case that "sweep" works which would tend to exonerate the power supply and the servo and the connections.)

Jim

PS.... to attach pix to posts, click the Additional Options link just below the typing area.

Edit PPS.... maybe post a photo of your actual setup?

First do what zk says and hook them up to an external power supply.... running one off an Arduino is marginal, two is asking for something to "pop". See attached pic....

Second, I'm assuming these are continuous servos, not normal servos, where the "position" value you send is actually the speed and direction? Make one of the speeds <90 and one >90 and they will go different directions. (90 is stop, then decreasing towards 0 increases speed one direction, increasing towards 180 increases speed the other direction. Stop might not be exactly 90, apparently: might have to experiment, maybe 89, maybe 91, who knows...)

EDIT.... I just looked at your pic again and notice you have them on the same control wire. For my suggestion to work you'll have to declare another servo on another pin, and control it separately.

HTH?

Jim

Are you asking how to create arduino sketches that you will be uploading to your arduino board

Well that's what I thought sreedevk meant, but in the light of the response to my response, I'm guessing it means "something else"

can I just plug in a 7.4v 3cell lipo directly to the board?

Always best to confirm for yourself on the product page; here's the Uno one for example.... 6-20 min-max, 7-12 recommended

You need to put the contents of one loop() inside the other one, basically. Or at least you need to start with that approach. I haven't looked at your sketches, but you'll also need to check that you don't have duplicate variable names and pins...

Welcome!

One way is to get a starter kit like this one (there are others too), and work through whatever documentation comes with it, and / or these tutorials.

Then when you have an actual project to work towards, use what you learned as building blocks and have a look at the Playground.

Thank you!
So, Are there like preloaded examples for Ultrasonic sensors that i can modify to suit my needs?

You'll find example for most things you're likely to need in the playground, but before you go there, work through the tutorials as suggested above.

You can put 11v into the Arduino anyway.... 7-12 recommended, 6 minimum (except for 5 in the USB).

So the 5v regulator won't help you supply power to the jack or Vin since it's too low.

Its called bisection method - http://en.wikipedia.org/wiki/Bisection_method -

Newton(-Raphson)  method is much faster - http://en.wikipedia.org/wiki/Newton%27s_method - it uses the first derivative which may be difficult to find

But why use a numerical method when there's a pure maths solution in the first place, using logs?

Edit.... unless "log" isn't implemented in Arduino's C?