I could save the world if I had this project completed

I am brand new to the Arduino but so far I love it and I am doing my best to learn how to use all of the vast features.

I need direction on which method to use. Any advice would be greatly appreciated.

Allow me to explain my project then I will welcome your direction.

Project... I have a fixed size tube that is 1.5 inches in diameter. I can wrap it with a mag wire in any size that is needed. I need to drop a metal object down this tube and as it passes by the coil, the Arduino needs to determine what kind of metal that just passed in the tube.

My though is the coil will change frequency if the metal is copper, or aluminum or brass or silver. The Arduino could read the different frequency and by the reading tell me what the metal happens to be.

The good news..... the tube is a fized size of 1.5 diameter. The metal is also fixed size of 1.25 dia and 2 inches long.

I thought about using a signal generator to energize the coil then use an Arduino frequency counter to determine the changes. But I am new to this stuff so I really have NO idea.

If you can suggestions, I am very much open to your ideas to solve this problem.

Thank you all in advance.

David

I would search all the DIY stuff on metal detectors to see how they work. Ferris to non is about all I think they know how to do.

I have no suggestions to make about a solution. But I am curious to know how it could save the world?

...R

You can not determin the composition of metal like this.

I agree with the above comment.

To determine metal composition from a large range of possibilities, expensive equipment and considerable expertise is required.

You want to count coins ?

How will that save the World ?

Thanks all. A metal detector can determine the metal type. I.e. Gold silver tin etc but I need info in the computer so I can use data. This is basic electronics 101. If you introduce a metal inside a air coil the frequency will change. Each metal will change the value. I'm just trying to discover the best way to use the arduino to create the field then read the results. Don't give up yet cause I know this is very possible.

Any more ideas?

If the tube with the coil around it is plastic or wood (non-conductor) and you have magnets outside to make a somewhat consistent field inside then your copper, or aluminum or brass or silver slug will get an induced field that will push some current through the coil (that won't sense the unmoving magnetic field).

The permittivity of the slug will affect how strong a field it generates. So will the speed with which it falls that the density will affect.

You might get away with the tube/coil and magnet on top of the slug inducing a field in the coil that induces a field in the slug and see where that gets you.

You might run current through the coil to induce field in the slug and see how much that slows the slug fall.

You might find enough difference to tell the metals apart.

Edit: but I see you are pulsing the coil .....

Ok now about saving the world...... well this project may not save the world but at least we are all making friends so who knows where this might lead ?

davidstanton:
Ok now about saving the world...... well this project may not save the world but at least we are all making friends so who knows where this might lead ?

So the project wont save the World after all ?

A good way to make friends you think, posting misleading posts ?

Don't keep it on topic folks, keep it about detecting the different kinds of metals, if that's even possible.

Come on guys did you really think I had an idea to save the world with an arduino. I was just joking around and making a joke. Where is your humor?

I'm really interested in making friends and giving back if I can.

I'm not interested in fussing with ya.

So once again I welcome your valuable input and suggestions on how to solve this soluation.

My basic idea is to find a way to determine the field inductance and then monitor the field change using something.

Any more ideas ? I know there are many brains in here that can solve this.

Thanks again

I know there are many brains in here that can solve this.

It still isn't clear what "this" is. You cannot determine the composition of different metals using coils.

What else would you like to do with a coil?

Hello My basic idea is that copper passing thru a coil will show a different inductance than aluminum passing thru the same coil. I may be wrong but that is kinda the way a metal detector works to determine the different kinds of metal.

Let me take a different approach.

Does anyone have a good program for a signal generator and an oscillator?

I can build one and test and see where that might take me.

Thank you all once again for taking the time to offer help

Best Regards

What frequency did you want? Here's 20 KHz:

byte triggerOut = 2;

unsigned long currentMicros;
unsigned long nextMicros;
unsigned long duration = 25UL; // flip every 50uS = 20KHz pulse
unsigned long elapsedMicros;

void setup() {
  pinMode (triggerOut, OUTPUT);
}
void loop() {
  currentMicros = micros();
  elapsedMicros = currentMicros - nextMicros;
  if (elapsedMicros >= duration) {
    nextMicros = nextMicros + duration;
    PIND = PIND | 0b00000100; // toggle D2 output by writing to input port.
  }
}

davidstanton:
Thanks all. A metal detector can determine the metal type. I.e. Gold silver

No it can't.
Many people wish it would but it simply can't. Those that claim it can are selling snake oil.

This has beem done for many years in commercial coin acceptors... that's how they work.

regards
Allan

that's how they work.

Commercial coin acceptors are carefully tuned to recognize the specific conductive and dimensional properties of the coins that they accept and to reject all others. None that I know of use tuned circuits.

That is a completely different concept from that of a device that is supposed to determine the composition of an unknown metal.

It is possible to use a tuned circuit to discriminate between ferrous and nonferrous metals, as mentioned much earlier in this thread. That is how many "metal detectors" work.

That is a completely different concept from that of a device that is supposed to determine the composition of an unknown metal.

Quite correct.

Any affect that can be attributed to the type of metal can also be attributed to mass and purity.

davidstanton:
Does anyone have a good program for a signal generator and an oscillator?

Does anyone know how to find general information on the internet?
Yes?
Then do it for me.