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1  Using Arduino / General Electronics / Re: Separate analog and digital regulators? on: Today at 01:11:40 am
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And why LC instead of RC; is there an advantage of one over another?
With an LC filter you do not get the drop in voltage that you get with an RC filter. This is because the resistance of the inductor is smaller than the resistance of the R you have to use.
Also an LC filter is a second order filter and the RC is a first order filter. The order of the filter is how quickly a low pass attenuates with increasing frequency.

I would have two separate ground plains and join them at one point.
There is no need for two supplies as shown here but it gives you the idea of two ground planes.
2  Using Arduino / Programming Questions / Re: After set a watchdog,the mcu died.I can't reset it though the Reset pin on: August 30, 2014, 05:27:21 pm
No it didn't , that was for posts in the body of the thread not attachments.
3  Using Arduino / Project Guidance / Re: First Project Help - Digital Potentiometer on: August 30, 2014, 05:11:28 pm
In the past I have used the TDA7318, you get a bit of a graphics equalizer with that one thrown in.
4  Using Arduino / Project Guidance / Re: potentiometer help on: August 30, 2014, 05:08:39 pm
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I was going to be using these ones
Poor choice, they are not very mechanically robust and will not stand the amount of ware you will inflict. It is normal to use wire wound pots for angle sensing. Yes I know these are expensive but they are accurate and will stand the ware.
5  Using Arduino / Project Guidance / Re: use arduino to control an adjustable boost converter? on: August 30, 2014, 03:08:00 pm
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Oh and resistance will not be adjustable.
Good job because that is a property of the load not the power supply and so impossible to do.

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Perhaps I would be better off building my own converter circuit?
How good are you at electronics?
That is a very difficult / impossible project for a beginner. You will have to use a PCB and get the design right. I have never known a professional power supply engineer get it right first time, it normally takes three iterations.

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but most of them in the 10 amp range are manually (via an adjustment screw)
You can normally replace that with a varying voltage from the smoothed PWM of an arduino.

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or way to big.
Yes your size requirements are pushing it but just about possible.

By the way how long do you want the batteries to last?
6  Using Arduino / Project Guidance / Re: Arduino to change pattern of 5v square wave? on: August 30, 2014, 03:00:19 pm
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if the wheel that the input side is reading has 3 notches that the hall effect sensor reads, can the Arduino take that particular square wave and output something as if the input wheel was a 5 notched wheel?
This is a lot more difficult than you might think.

This is because in effect you are requiring software to predict the future. While you can do this for specific rigid cases it is hard / imposable to make a universal one.
The closest you can get is a sort of averaging, you get this with a circuit called a "phase locked loop"
http://en.wikipedia.org/wiki/Phase-locked_loop
This can be implemented in software although it is more usual to implement it in hardware. Basically you have to divide down to get a mark / space ratio of 1:1 and then multiply up to get the frequency you want.
7  Using Arduino / Project Guidance / Re: Handheld terminal suggestions welcomed on: August 30, 2014, 02:54:03 pm
There are a number of different terminals it could emulate.
http://en.wikipedia.org/wiki/Terminal_emulator
Has a list of some of them.
8  Using Arduino / Programming Questions / Re: Understanding Code on: August 30, 2014, 02:48:29 pm
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So if i am reading the data sheet right, it says send a 0 to read and a 1 to write before you go on to the next byte. This is sent after the address is sent.
No it is sent with the address as the least significant bit.

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Am i right to assume the wire.read and wire.write commands take care of this!
Yes this command shifts the address bits one place to the left and adds 0 or 1 as appropriate but it is all sent out as one byte.

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So how do you find out what these are for a given library?
It should be in the documentation of the library, if not look at the code of the library. Ultimately the numbers you need to send are in the data sheet of the device.   
9  Using Arduino / Programming Questions / Re: Galileo: my servo runs only in one direction, it doesn't turn back on: August 30, 2014, 02:42:27 pm
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No, it doesn't need its own power because the Intel Galileo provides enough power for it.
True the Galileo comes with a 3A supply, but you have to consider if your servos are generating enough interference to disrupt your processor.

So it is not just a matter of having enough available current, your servo supply have to be decoupled.
10  Using Arduino / General Electronics / Re: boosting regulator supply on: August 30, 2014, 02:36:58 pm
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with the following attached design:
does the input have to be equivalent to output for current?
Yes.

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if i have wall wart  - 12vdc  @ 1A and need 5v @ +/- 5A for output, will this design pull the 5A from wart or create from the TIP2955/MJE2955 without burning the wall wart?

The circuit you showed is not a boosting regulator it is a simple step down linear regulator. The TIP2955 is just a simple transistor not a regulator.

What you need is a boost or step up switching regulator. Something like a TPS40210 or a TPS61256. With that you can swap excess current for voltage.
The other way round is called a buck switching regulator where you swap excess voltage for current.

However you can not get more power than you put in. So 12V at 1A is 12W of power. If you could convert at 100% you could get 5V at 2.4A. But more likely your efficiency is going to be 80% so you get (12 * 0.smiley-cool / 5 = 1.92A.

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if i understand correctly, i can add multiple 2955's for more current
No you can't.
1) It is not a regulator
2) You can not create power only distribute the voltage and current in another way and loose some power into the bargain.

Have a read of this.
https://www.dimensionengineering.com/info/switching-regulators
11  Products / The Arduino Starter Kit / Re: Project 7 Issues on: August 30, 2014, 10:51:22 am
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I already have it in the OP but here it is again:
No you didn't you posted two code fragments.
The reason you got an error was because you attempted to assign a value to an initialized variable outside a function. If you move it into the setup function it will compile like this:-
Code:
int buttons[6];
int notes[] = {262, 294, 330, 349};

void setup() {
  Serial.begin(9600);
  buttons[0] = 2;
}

However what is this array? You do not use it anywhere else in the code so it is pointless.

Are you sure you are copying this code correctly?
12  Products / The Arduino Starter Kit / Re: Project 7 Issues on: August 30, 2014, 09:28:45 am
If it says that it is wrong.
However unless you post all your code I can not correct the other mistakes you have made that removing that incorrect int then shows up.
13  Products / The Arduino Starter Kit / Re: Project 7 Issues on: August 30, 2014, 08:46:47 am
You simply can not do this:-
Code:
int buttons[6];
int buttons[0] = 2;
Because you are defining a variable twice. You can do:-
Code:
int buttons[6];
buttons[0] = 2;
the int bit says this is a variable I will use as an integer.

 
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but the only value I get is "0".
Then you have wired it up wrong.
14  Using Arduino / Project Guidance / Re: potentiometer help on: August 30, 2014, 08:42:23 am
You need to know what speed you need the updates to occur in terms of samples per second to know if this is feasible.
15  Using Arduino / General Electronics / Re: Connecting a 5V Arduino Pins to a 3.3V Raspberry Pi GPIO's pins on: August 30, 2014, 05:53:17 am
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it's all making a hell of a lot more sense already
Good.

Just a point, it is wise not to use pins 0 & 1 on the Arduino as they are used for serial communications.

Not sure what you mean by pin 1 & 2 on the Pi. But in general avoid GPIO 2 & 3 ( or GPIO 0 & 1 on an issue 1 board ) as they are the I2C bus lines and have a 1K8 pull up resistor connected to them. It will still work with these being just I/O pins though.
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