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46  Community / Bar Sport / Re: What happens when they rebel? on: October 21, 2013, 06:46:42 am
Might be able to deliver other stuff than books, too

There is video somewhere on youtube of a quadcopter fitted with an uzi being fired remotely.

Also read recently several hundred people have applied for licences to shoot down drones flying over their property.

One problem with drone counter measures is that some of these devices seem to be getting very small. It might be hard to even know they are there.

47  Using Arduino / Project Guidance / Re: Car park monitor on: October 03, 2013, 09:41:30 am
Are there barriers can't you count them in and count them out plus have a webcams for a more general security overview?
48  Using Arduino / Project Guidance / Re: Identifying Chess pieces in a Chess board on: October 03, 2013, 04:05:27 am
Mike, I think there is a potential problem but I don't think your pdf describes it.

The token, lets call it 'A' is over pickup coil 1.
When the excitation coil is active you are saying pickup coil 1,2 and 3 will all detect token 'A' is that correct?

That is not a problem though is it because a mux is being used to choose the excitation coil for that row and a mux is being used to chose pickup coil 1 to read from?

Is the real issue not when you have 2 or more tokens?
If we leave token 'A' over pickup coil 1 and place a second toben 'B' over pickup coil 2 are you saying that pickup coil 1 will read both 'A' and 'B' ?

49  Using Arduino / Project Guidance / Re: Arduino Temperature Controller on: October 03, 2013, 03:46:21 am
I am really new to arduino and I've never programmed anything for it before

But you have programmed before?

Just start small and build things up step by stepe.g.
Write a program that just keeps saying "hello world".
Then get it to output a number.
Then add your temperature sensor and output its reading checking it changes as you would expect.
Add an LED and try turning it on/off as the temperature moves between limits.
Add your LCD and output to that.
Add your fan control.

Don't try heading straight to the final solution, you will end up with lots of code none of which you trust.
50  Using Arduino / Project Guidance / Re: Variations on Spaceship Interface on: October 03, 2013, 03:37:40 am
So instead of a switch, the IR sensor would detect light and turn on the blinking lights

I agree it is not clear what you mean by the above.
Where does the IR light come from and what turns it on?

It makes more sense if the blinking lights come on when the IR sensor stops seeing an IR source e.g. when a train cuts a beam.
51  Using Arduino / Project Guidance / Re: Advice appreciated on project please. on: October 03, 2013, 03:32:43 am
The code was written to allow an Arduino to be used without the need to learn C++

Well, it will let you use an Arduino in a limited way but that could still be of interest. Presumably you have documeted the interface well?

There is an area of the site where people can display their projects. Why not post your code here first along with the documentation so that people can comment on it.
52  Using Arduino / Project Guidance / Re: Identifying Chess pieces in a Chess board on: October 01, 2013, 02:40:32 pm
Looks fun, haven't played in over a decade

If you visit this excellent site you will get a game, for free, in a few seconds (I suggest unticking 3mins and 5mins and ticking 10mins).

The solution using magnets in pieces to activate reed switches is not going to be affected by stray magnetic fields.
The solution of having resistors in pieces will be very dependent on making good contacts.
Magnets are a better solution. The RFIDs in theory are better still - if there is a practical way to implement them, however if Grumpy-Mike thinks there is an issue that needs to be seriously considered.
53  Using Arduino / Programming Questions / Re: Created Pause Function - Not Executing as Expected on: October 01, 2013, 02:28:25 pm
I was stating the case if the runID was true (not 0), then to execute the run program
What you have written is a bitwise AND which will always result in the 'if' being false.
It is not too obvious why you are using bitwise ANDs and ORs they are not adding clarity.

54  Using Arduino / Programming Questions / Re: Created Pause Function - Not Executing as Expected on: October 01, 2013, 10:14:43 am
What does this do?
if (runID & 0) {
55  Using Arduino / Project Guidance / Re: wanna make a laser-show - can I use a DC motor? on: October 01, 2013, 10:04:13 am
I don;t understand the design. What do the DC motors do spin mirrors? why would you not use servos or steppers to drive the mirrors to position?
56  Using Arduino / Project Guidance / Re: Identifying Chess pieces in a Chess board on: October 01, 2013, 09:58:10 am
You may have well asked, how do you stop magnetic interference?
Not really. Having electrical contacts all over the board sounds messy and will be distracting visually as well as because of the need to place pieces carefully. Magnetic fields are not an issue in any of the chess settings I can think of.
57  Using Arduino / Programming Questions / Re: Programming steps using millis() on: October 01, 2013, 09:18:42 am
Getting my head around the logic required to use millis() properly here is proving troublesome.

millis() gives you the current time.
Read and record the current time as the Start time.
Calculate the End time by adding your variable time to the Start time.
Keep reading the currnet time till it exceeds or is equal to your End time.

Your code does not sit there doing nothing as it would with a delay.
Complex timing schemes can be boiled down to variations of the above.
58  Using Arduino / Programming Questions / Re: HELP with blink without delay.. on: October 01, 2013, 06:45:07 am
Just cannot make out how to do it ..

Yes you can, think;

You note the start time and turn the LED on.
30ms after the start you turn the LED off.
1030ms after the start time you repeat the process.

What you see is;

      0ms turn on.
    30ms turn off.
1030ms turn on.
1060ms turn off.
2060ms turn on.
59  Using Arduino / Project Guidance / Re: Identifying Chess pieces in a Chess board on: October 01, 2013, 06:27:32 am
Have you really convinced yourself beyond any doubt that you need to be able to sense the identity of each piece as well as its presence?

You don't need identity but pawn promotion poses a problem you cannot solve (as far as I can see) without also keeping track of major pieces (i.e. not pawns) that have been captured so you know what piece a pawn has been promoted to.

In other words you need to be able to figure out what piece is on each of the 64 squares but also have an addition 14 squares off-board to hold captured pieces.

The RFID solution identifies pieces and so is elegant, but the electronics seem to be getting more complicated.

Mixographer you used reed switches, how did you handle pawn promotion, did you ignore it, or assume pawns always became queens, or do you provide additional data to the system manually?
60  Using Arduino / Project Guidance / Re: Identifying Chess pieces in a Chess board on: September 30, 2013, 04:27:31 pm

The problem is that there will be inductive coupling between the antenna so no amount of switching is going to isolate one token.

So if the muxes are used to select the transmitter in column 'B' and the receiver in row 'B' what you are saying is that the transmitters in columns 'A' and 'C' will also fire and the receiver will see multiple tags is that correct?

Is there no way round this by say reducing the transmitter power (the rfid tags will be right on top of the transmitters) and by grounding the transmitters that are not supposed to fire?

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