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61  Community / Bar Sport / Re: Holy Crap Lightning Strike Damage! on: August 11, 2014, 08:44:57 pm

http://youtu.be/wZtWWO8cfH0

About 3/4ths in after he's finished showing off the pictures, check out the cb radio and the damage caused by a strike, that's insane!
About 15 years ago there was a lightening strike about 100ft from my house. It damaged a neighbours house quite severely (it demolished his chimney and set fire to some of the interior) and damaged another neighbour's TV, presumably through the aerial. But what was more surprising was that it blew up my telephone and (dial-up) modem. My telephone service cable runs underground until it enters my house!
62  Using Arduino / General Electronics / Re: Is it a standard to call outputs "Y" on ICs? on: August 11, 2014, 08:08:49 pm
It varies. Sometimes Y can be either an input or an output and Z is used to denote the opposite
(74HC4067 multiplexer/demultiplexer). Usually address pins are A (address), but sometimes S (select?). There seems to be no rhyme or reason to it. Different manufacturers use different conventions.
63  Using Arduino / General Electronics / Re: what's this phenomenon called? on: August 11, 2014, 07:54:11 pm
Quote
Bipolar Power Supplies
<poor taste joke alert> Can you cure those with lithium batteries? </ptja>
LOL!
64  Using Arduino / General Electronics / Re: Op Amp Hilarity on: August 11, 2014, 07:44:55 pm
And then there is (or rather, was)
Have they been superceeded by the F&*%|^!' Fast version?  smiley-grin
65  Using Arduino / Programming Questions / Re: Running only one concurrent instance of a function on: August 11, 2014, 07:10:36 pm
How, by definition, can the only one of a thing be concurrent?
He alone is unanimous in his definition...
66  Using Arduino / Project Guidance / Re: connecting servo to motor shield on: August 11, 2014, 06:46:31 pm
Both wrong this is just the standard problem with motor shields and servo. the PWM for the speed control on the motor uses the same timer as servo.h uses to control the servo and this screws things up. Rule of thumb - you can not use servo with a motor shield. Try newservo - look in the playground.

Mark.
Check the Adafruit website. They claim their motor shield works with both at the same time.
67  Using Arduino / Project Guidance / Re: Stuck on Blackjack Program on: August 11, 2014, 06:34:04 pm
You can reduce this:
Code:
String Suit[] = {" of Spades"," of Clubs"," of Diamonds"," of Hearts"};
to this:
Code:
String Suit[] = {"Spades","Clubs","Diamonds","Hearts"};
...
        Card = randomCard + " of " + randomSuit;
saving 12 bytes and this:
Code:
String cardNames[] = {"Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10", "Jack", "Queen", "King"};
to this:
Code:
Char cardNames[] = {"A", "2", "3", "4", "5", "6", "7", "8", "9", "T", "J", "Q", "K"};
saving a further 26 bytes, but that uses a non-standard abbreviation (T) for ten.

Why not just get a random number between 1 and 13 (no need for an array) and use if/ else or switch/ case to name the 3 court cards (11, 12 or 13), or ace, if selected.
68  Using Arduino / Project Guidance / Re: Beginner in a time crunch on: August 11, 2014, 05:44:24 pm
You want two timing loops, one 10 minutes (for the servo) and the other 4 minutes (for the green LEDs).
That's not possible using delay().
Read, understand and embrace the principle of the  'blink without delay' example in the IDE.
I also suggest that you look up 'Finite State Machine'.
69  Using Arduino / Programming Questions / Re: Translation the shaft encoder data on: August 10, 2014, 09:09:11 pm
The encoder will enable you to determine how many times each wheel has turned.  That's all.

If your wheeled robot is going in a straight line,  and the wheels are not slipping on the floor,   then each complete rotation of the wheel will become a movement across the floor,  equal to the circumference of the wheel.

If the wheels are turning with different speeds,  or even in opposite directions,   then the robot will turn.  And in addition to turning,   the relationship between wheel turns and distance travelled will break down. 

If you run the left wheels forward and the right wheels backwards,   the robot will turn to the right.   It might go forwards and turning right,   like a car would,     or it may turn "on the spot",  like a tank or a shopping trolley can turn.   Without very detailed analysis of the geometry of the vehicle and the friction characteristics of the tyres,  it is almost impossible to model either in a general way or a specific scenario,    without making a lot of heroically over-simplified assumptions.

I think that your objective is unrealistic.

There is no "formula"  that will do what you seek.

I suggest that you build your robot,  and then carry out a series of experiments where you measure the path response to various speed and steering inputs,    and then you can develop some kind of empirical predictive model based on the results of those experiments and assuming that the robot's future behaviour won't change.
And, unless the robot is a balancing one, there will have to be a third point of contact. The position of this third point of contact, with respect to the wheels, and its construction/friction, will have a great effect on how the robot moves when the wheels are turned.
70  Using Arduino / Programming Questions / Re: program is not working after few hours until reset on: August 10, 2014, 08:54:30 pm
I have done a program for turn on relay using external interrupt input signal of another relay. When pregame is running it works properly. But after few hours gone and give again interrupt input, output relay is not turn on. how ever after reset then again program work correctly.   : smiley-sad smiley-sad smiley-sad smiley-sad

so can anyone tell me that what reason for that and please help me to clear that fault.
Sorry, but my crystal ball has crashed and I'm unable to read your code.

Note to self...Upgrade to a Windows 8.1 crystal ball urgently.
71  Using Arduino / Programming Questions / Re: What else can use unmolested Uno scripts? on: August 10, 2014, 08:26:54 pm
If I decide to go to a MEGA, what all is involved in changing the coding?  Say, for a clock as an example?  Just the basic readers digest version, please  smiley
The only difference I found between the Mega and Uno is that the analog pins (A0 - A5) on the Uno can be addressed as pins 14 - 19, but on the Mega have different numbers. You can still address them as A0 - A5 on the Mega, but not as 14 - 19. Apart from that, I've found no difficulty in moving sketches from the Uno to Mega.
72  Using Arduino / Programming Questions / Re: paralax range finder and blink without delay on: August 10, 2014, 08:04:27 pm
Feel free to analyze the rest of the code and give any advice you think might help.
All variables associated with millis() should be unsigned longs. It makes them able to hold numbers twice as big!
Code:
  if(ledState == LOW)
     ledState = HIGH;
     else
     ledState = LOW;
can be reduced to:
Code:
ledState = !ledState;  //inversion
73  Using Arduino / Project Guidance / Re: connecting servo to motor shield on: August 10, 2014, 07:48:42 pm
Hi everyone recently got adafruit motor shield v1.0 and was wondering how i go about connecting the servo as nothing seems to be wroking?
You appear to be trying to run your servo from the  Arduino power supply. You haven't stated what type of servo you're using, but usually a servo requires more current than the Arduino can supply. I suggest you use an external supply for both your motors and the servo.
N.B. The Adafruit motor shield V1  has the servo numbers reversed on the silkscreen.
74  Using Arduino / Project Guidance / Re: Arduino fire alarm notification on: August 10, 2014, 07:33:28 pm
Do you see any major problems with my idea?
Martin
Yes. What if your Arduino catches fire?   smiley-mr-green
75  Using Arduino / Project Guidance / Re: Detect liquid on steel plate on: August 10, 2014, 07:21:25 pm
What technique would you use to detect how large area of a steel plate is covered by ketchup or a similar liquid? Is capacitive sensor appropriate?
If you know the temperature of the plate and the density, viscosity and surface tension of the liquid at that temperature, all you need to measure is the extra weight that's added to the plate by the liquid. You can then use the density to work out the volume of the liquid and the viscosity and surface tension to calculate its spread over time. All this assumes that the plate is dead level and that the liquid is applied to the plate in only one place.

Or you could just use a squeegee to spread the ketchup evenly over the plate for 100% coverage....

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