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556  Using Arduino / Programming Questions / Re: AnalogRead for a Random Seed. on: January 06, 2014, 10:33:21 am
Forget the RF. Amplify the signal from a reverse biased PN junction and use a schmitt trigger to square it up.

http://www.edn.com/design/analog/4420926/White-noise-source-flat-from-1Hz-to-100kHz

Or re-create the lavarand. 8^)
557  Using Arduino / Programming Questions / Re: Remote programming arduino on: January 02, 2014, 06:47:40 pm
And you would probably need to install the IDE on the other computer in order to have the necessary programs (avr-dude for one) to invoke.
558  Using Arduino / General Electronics / Re: Measuring shunt current and opamp on: January 02, 2014, 04:07:04 pm
For your reading pleasure:
http://www.maximintegrated.com/app-notes/index.mvp/id/746
559  Using Arduino / Programming Questions / Re: GOTO Lsetup on: January 02, 2014, 01:58:42 pm
There is also the setjmp and longjmp() C commands.
560  Using Arduino / General Electronics / Re: Measuring shunt current and opamp on: January 02, 2014, 10:28:09 am
Probably the input offset voltage of the op amp. At a gain of 174 it only needs to be 1 mV to produce 170 mV of offset.

Also, your schematic is hard to read. I cannot tell what are connections and what are crossovers.
561  Using Arduino / Programming Questions / Re: Trying to combine statements, failing miserably....... on: December 19, 2013, 07:17:47 pm
C/C++ has a defined type for buffer lengths, size_t.
562  Using Arduino / General Electronics / Re: Lithium cells / batteries. More efficient to step-up or step-down on: December 19, 2013, 02:28:13 pm
One other factor is the same one that makes transmission lines run at very high voltages. Stepping down will draw lower current from the battery and incur less I-squared-R loss.
563  Using Arduino / General Electronics / Re: Need to measure -30c to 150c on: December 19, 2013, 11:13:42 am
A type T or J thermocouple would work, too.

The current requirement is pretty small, 50 uA, so a battery would last a long time.

You could use an Op-Amp to level shift the voltage.
564  Using Arduino / General Electronics / Re: Darlington output voltage and load connection on: December 18, 2013, 07:01:35 pm
If it is really a darlington, you need a Vbe of about 1.4 V to turn it on since you have two Vbe junctions to feed.
565  Using Arduino / Programming Questions / Re: Don't understand operator as used in a statement. on: December 18, 2013, 06:15:03 pm
Not exactly.
I was just showing with the parens that the ! operator is totally separate from the assignment operator.

It is a quick way to toggle ledState.

Though the ! operator is used exactly the same. It negates ledState, the = then assigns this new value to ledState.

So if ledState is false, !ledState is true, and that is placed back into ledState so that after the statement, ledState is true.
566  Using Arduino / Programming Questions / Re: Don't understand operator as used in a statement. on: December 18, 2013, 03:18:56 pm
think of it this way:
Code:
ledState = (!ledState);
567  Using Arduino / Project Guidance / Re: Fastest possible search in small arrays with different methods on: December 18, 2013, 03:13:47 pm
smoes:
you can ignore the sample data. It is just an example and does not relate to the real data, as the OP says.

It will work fine for a search algorithm, but not a hashing one like you provided.
568  Using Arduino / Programming Questions / Re: What does the "?" and ":" do in this Code on: December 18, 2013, 10:23:03 am
Really cjdelphi?

How do I know what variable gets assigned to in your syntax?
What if you want to assign to a variable that doesn't show up anywhere else in the expression?

i.e.
Code:
y = (x>10)?(30):(40);

Your syntax is the one that makes no sense.
569  Using Arduino / General Electronics / Re: Calculating inductance on: December 18, 2013, 10:00:51 am
The impedance is:
Z=2*pi*f*L

so if you want the inductance at a given impedance:

L = Z/(2*pi*f)

In this case:
16/(2*3.14159*1000) = .00255

so .0033 is the closest standard value.
570  Using Arduino / Project Guidance / Re: Fastest possible search in small arrays with different methods on: December 17, 2013, 05:47:12 pm
holmes4:
If addr is the correct type, the sizeof() is not required and will in fact cause problems. The compiler is smart enough to know that when using pointer arithmetic the jump is scaled to the size of the array, so if you add 2 to a pointer it will point to the second object whether a byte *, long * or float *.

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