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1  Using Arduino / Motors, Mechanics, and Power / Re: Servo basic - description for type working with voltage range wanted. on: September 19, 2014, 11:39:40 pm
I am not aware of any servos which work with position controlled by voltage.

None of the RC/hobby/model servos work that way,   they use pulse width control.

I have seen various industrial servos that use other methods.
2  Using Arduino / Programming Questions / Re: 3D maths to sutract gravity from accelerometer data on: September 19, 2014, 11:35:02 pm
You want the accelerometer to be as close as possible to the centre of mass,  to minimise the apparent acceleration due to the device rotating.
3  Using Arduino / Programming Questions / Re: 3D maths to sutract gravity from accelerometer data on: September 19, 2014, 11:25:54 pm
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Anyway, the problem is that the accelerometers show 1.0G downwards all the time due to the force of gravity.

It should be showing +1g straight up,  due to the force of the tabletop,  or whatever else is stopping your device from falling into a bottomless pit.
4  Using Arduino / General Electronics / Re: ANSWERED 555 resistor value for Tm = Ts on: September 15, 2014, 01:37:13 am
In Reply #1 above,   how does the first schematic have duty cycle adjustment ?
5  Using Arduino / Sensors / Re: ACS712 sparkfun breakout questions - too unstable to be useful? on: September 14, 2014, 11:54:17 pm
Integrating to get a smoother output is fine,    as long as you want to measure a low-frequency current.
6  Using Arduino / Sensors / Re: Air pressure sensor - Tire pressure on: September 14, 2014, 11:49:36 pm
There are a lot of kits on ebay

Try search with "tire pressure monitor wireless"   $100-$300 dollars.
7  Using Arduino / Sensors / Re: Air pressure sensor - Tire pressure on: September 14, 2014, 11:43:38 pm
Lots of cars have them now,  I don't know how they work,  but it is hardly rare or exotic any more.
8  Using Arduino / Sensors / Re: Swimming Pool Water Level Sensor on: September 14, 2014, 11:41:00 pm
Sorry,  I didn't realise when I made that last post,   that the problem was solved a year ago.

What sort of wireless range do these panstamp gadgets have ?
9  Using Arduino / Sensors / Re: Swimming Pool Water Level Sensor on: September 14, 2014, 11:20:41 pm
Put a washing machine pressure sensor on one of the pipes near the filter.   When the pump and filter are not running,  the pressure will be directly proportional to the height difference between the sensor and the water level in the pool.
10  Using Arduino / Motors, Mechanics, and Power / Re: Help with Large Scale Servo Project on: September 14, 2014, 09:25:54 pm
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Is the regulator too small for the job,

Yes.

I'd use two regulators,   with a large capacitor on the output of each of them,    and supply the arduino from one,   and the servos from the other.

11  Using Arduino / Motors, Mechanics, and Power / Re: Help with Large Scale Servo Project on: September 14, 2014, 09:24:01 pm
The servos will use a lot more than 180 mA  when running,  or when holding a load.

The statement "the servos draw 180 mah with no load",  is nonsense.   Even "... draw 180 mAh... "  is still nonsense.
12  Using Arduino / Programming Questions / Re: display all characters at once in serial monitor on: September 14, 2014, 09:04:43 pm
Your code won't work if val is a char array.
And it won't work if val is an object of the String class either.

Decide which method you are going to use,    and then stick to it.

13  Using Arduino / Programming Questions / Re: Calibrating an Accelerometer on: September 14, 2014, 08:50:24 pm
You also need to be clear, whether you are trying to use the sensor to measure orientation,   or actual acceleration.     Because the objectives of the "calibration" process outcome would be different.

It's all very well to point the sensor axis up and down,   and see what reading you get in 'g',   and then take the midpoint,   But if this midpoint corresponds neither to a horizontal position of the axis,   nor to a zero acceleration,    then it probably doesn't actually serve a useful purpose.

You probably want the numerical relationship between what the sensor reads,   and what you assume the acceleration to be,   to be piecewise-linear  rather than just plain linear.

   

14  Using Arduino / Programming Questions / Re: Calibrating an Accelerometer on: September 14, 2014, 08:45:19 pm
You also might have an issue with Serial.print( ) not working properly for floats.
15  Using Arduino / Programming Questions / Re: Receiving erratic values for potentiometer, rocker switch, WITHOUT touching them on: September 13, 2014, 07:49:15 pm
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Hm, I see what you mean - although I don't think I should have to.  The sketch/library I am using is pretty darn detailed, so I'd think they would have considered that and included it in the code.  

Your petulant attitude unfortunately cannot defy the laws of physics,  not matter how darn detailed your sketch is.    If you sample a constant voltage with an a/d converter,   you are going to get successive readings which differ by one or two counts.    That's just the way it is.   If the person who wrote yoir detailed sketch considered that issue,   they obviously never tested it.

"Setting a range" of inputs,  as suggested above,  isn't going to fix the problem for a pot input that can be turned to any value.   Setting a range of 120-130 is going to work when you expect an input value of 125,  or very close to it.    Having a range is still going to have problems if your input is 130,   you might get 131.   What you need is logic that locks into a stable value  and then ignores changes of +/- 1 or 2,  until you get a change which is more than 2.
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