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451  Using Arduino / Project Guidance / Re: A project Idea on: September 08, 2013, 05:12:00 pm
Dear 1ChicagoDave,
   I am pretty sure you are right. I am trying to come up with some sort of algorithm that would solve this problem. In the algorithm I would have to take the weight and probably determine the velocity of a certain sized fan from the weight to keep the object in the air.

Got it.

As Henry_Best pointed out, you'll likely need to limit your algorithm to similarly shaped items.
And similarly sized.
Quote
If you're planning to keep this project rather small in size (at least at first), most/many computer fans have built in speed control using PWM on a separate wire (separate from power & ground) much like a servo.  And some of those things can move quite a bit of air...especially when confined within a tube.

Good luck!
As 1ChicagoDave pointed out, wouldn't it be simpler to just measure the height of the object in the tube and adjust the fan accordingly. Too high - slow the fan. Too low - speed up the fan. There would then be no need for any weighing.
452  Using Arduino / Project Guidance / Re: servo knob problem on: September 08, 2013, 05:00:38 pm
It sounds to me like a hardware problem. Have you tried a different pot? The one you're using may be 'crackly'.
453  Using Arduino / Project Guidance / Re: A project Idea on: September 08, 2013, 04:44:35 pm
The factor which you haven't accounted for is surface area, unless all your objects will all be the same size and shape. The airflow needed to keep a sheet of paper afloat is far less than if the same sheet of paper is folded 8 times.
454  Using Arduino / Audio / Re: Piezo buzzer - Winning and loosing sound FX on: September 06, 2013, 10:56:51 pm
What have you got so far?
Post your code.
455  Using Arduino / General Electronics / Re: Doorbell button as input on: September 06, 2013, 10:51:49 pm
Hi, do you really need a light in the switch, if not then remove the globe and it will then be a simple switch.
The globes cold resistance is only a few ohms at most so its acting as a closed switch in parallel with your press button.

Of course! I can't believe I missed that. After removing the bulb it continued to do the same thing until I connected it like this:
Code:
3.3 volt ----- doorbell switch ------ resistor ------ ground
                                  |
                                 pin 11

Is that what bigred suggested? It's one of the ways I had tried wiring it up before. Anyway, it works perfectly now! I had considered replacing the incandescent bulb with a LED but I wasn't sure how difficult it would be; after opening the switch to remove the bulb, I don't think it will be very hard at all and I may tackle it tomorrow night.

And for the record, my previous chime used 16v.

Thank you all for the help. I will follow up with a link to photos/video when I get some up in case you're interested.
If you connect your LED seperately you could have it on all the time, but that would involve running a third wire from your bell push.
456  Using Arduino / General Electronics / Re: Axial / 'inline' stud connector on: September 06, 2013, 10:27:33 pm
Hello all,

In this day and age - everything seems to exist - except for what I'm after.

Of course, normal high power ring terminals exist to connect high power cables to other cables / devices / studs. However, i'm looking for an inline solution, so that the cable does not connect at right angles - I know there are of course mil-spec connectors that achieve just this - but I just want to be able to screw down a power cable inline with a power stud, such a solution would just be a simple two piece contact - however, I just can't think what the name of them would be if they exist, so can't seem to find them.

These must exist?

Failing this, I suppose just bend a ring terminal 90 degrees and cover it with a boot - but, that's not directly inline. I don't like mess, some may call it OCD.

You haven't said if you want this to be a permanent connection or a removable one.
457  Using Arduino / General Electronics / Re: Axial / 'inline' stud connector on: September 06, 2013, 10:08:55 pm
If you're really that OCD you could make your own connector in a fashion similar to some coax connectors or, as would be used in plumbing, a flare nut. You'd need a brass "coupling nut" and a brass washer to solder on one end of the coupling nut to constrict the ID. A steel coupling nut and washer would also work if you have access to a welder, or if you have a lathe and tap/die set just make it yourself.

To prevent the wire from pulling through the washer's ID just give it a large blob of solder. You could also do that in a neater fashion by drilling a blind hole of appropriate diameter into a block of aluminum, sticking the wire inside the hole, and then filling it with solder.
How do you get solder to 'stick' to aluminium?
458  Using Arduino / Project Guidance / Re: Smart Grocery Cart on: September 06, 2013, 09:46:51 pm
Problem with RFID is most items do not have RFID tags, and RFID tags cost money. Barcodes are already on (almost) everything and they're practically free.

I'm not sure putting a scale in each cart is cost effective or accurate -- scales need to be level and motionless to be accurate. What I would do is have a cart scale that weighs the whole cart just before the customer leaves the store (subtracting, obviously, for the weight of the cart). It can compare the net cart weight with the cumulative weights of the items individually scanned previously. Fruits and veggies can be processed on a separate small scale with a touchscreen menu interface (to select the fruit/veggie type) before cart weigh-in.

Or instead of barcodes/RFID, how about an IR sensor in front of each item on the shelf. When an item is detected as being removed from the shelf, the nearest iPad registers the item as purchase pending. (The shopper can return the item to the shelf to clear it back off their list -- needed for folks just reading labels.) Only trick then is deciding which customer picked up the item... hopefully your customers aren't packed in so tight an item removal is registered on the wrong iPad.

Maybe I have the mind of a thief, but your IR idea is easily circumvented. Imagine two bottles of wine next to each other on the shelf. One is an expensive, Chateau grown wine, the other is cheap 'plonk'. It would be easy to slide the expensive bottle sideways along the shelf until it's in front of the sensor for the cheap wine and then remove it. Weighing the bottle wouldn't be much use, as the bottles will probably weigh the same.
459  Using Arduino / Project Guidance / Re: Measuring dough rising factor on: September 06, 2013, 09:32:04 pm
To make the dough rise, I presume that you're using some kind of yeast. It may be possible to measure the concentration of CO2 given off by the yeast to calculate how far the process has gone and, therefore, how much your dough has risen. CO2 sensors are available.
460  Using Arduino / General Electronics / Re: Doorbell button as input on: September 05, 2013, 11:04:01 am
As for getting the switch to light, I'm sorry to say that if it was designed for 120v, I don't think you're going to get very much light at all out of it from a 5v source.
Please tell me what doorbell push would have mains voltage running through it? Unless, of course, you want to electrocute callers on rainy days.

Wait. That gives me an idea. A 'special' doorbell button for use by JW's. smiley
461  Using Arduino / Programming Questions / Re: Looking for general guidelines merging sketches on: September 04, 2013, 11:09:31 pm
Thanks Henry,
I've tried what you suggested and it compiles but when I upload it and try the button it doesn't respond.
Did you see what I wrote above about the buttons not being read during the time that the program is in the while loop (//Wait for a start bit)?  Change the while statement to an if statement (//If start bit received).
Also, see the 'blink without delay' example to get rid of the delays. No buttons can be read when the program is in a delay.
462  Using Arduino / Project Guidance / Re: Smart Grocery Cart on: September 04, 2013, 10:24:42 pm
It could also work on weight. Adding an item to the trolley without scanning it would cause an alarm. You'd have to know the weight of every item to ensure it is put in the trolley after scanning and not replaced by a different, more expensive item. The shopper can weigh their fruit, etc. themselves and have the scales print out a sticky barcode label with the weight and cost encoded in it. Weighing 3 apples but putting 4 into the bag before sealing with the label would mean that the barcoded weight would not agree with the weight added to the trolley.

Your problem would be to keep the weighing device in the trolley accurate over a large range.
463  Using Arduino / Project Guidance / Re: Pot motors held issue on: September 04, 2013, 10:07:50 pm
I have a sainsmart(Ada fruit) motor shield l293d, just got it. I went on the arduino playground and installed the library. Tried the example codes and the motor works just fine. I want to hook it up to a pot, and control the motor through the motorshield. Here is the problem, after reading and rereading, cannot find the motorPin designation for motor 1 terminal on the shield. Is their one? I have done this on the UNO, and used 3 as my motorPin. On the shield, I hook it into the terminal... How can I attach to a pin? Or is there a function that replaces a pin with a terminal?
Code:
#include <AFMotor.h>

AF_DCMotor motor(1, MOTOR12_64KHZ);

const int potPin = A0;
int potVal = 0;
int mappedPotVal = 0;

void setup()
{
  pinMode(potPin, INPUT);
}

void loop()
{
  potVal = analogRead(potPin);
  mappedPotVal = map(potVal, 0, 1023, 0, 255);
}
Add in loop()
Code:
motor.setSpeed(mappedPotVal);
464  Using Arduino / Programming Questions / Re: help with code (battery tab spot welder) on: September 03, 2013, 11:06:05 pm
Yes Henry_Best A Big THANK YOU   and i understand how the code works wish i could of grasped it earlier
You're welcome.
465  Using Arduino / Programming Questions / Re: help with code (battery tab spot welder) on: September 03, 2013, 11:03:21 pm
Thank You Henry_Best for all your work
"Experienced old Whitebeard with a Full head of Hair..."
That could apply to me too, Doc, although my hair is receding slightly and we may be experienced in different things  smiley-wink
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