Controlling intensities of an 12v electromagnet using PWM signals

Hi everyone!

I'm new to electronics stuff :sob: & pls pardon me for my stupid questions.

Here is what i'm going to do: I want to suspend a magnet+weight(variable(0-250g)) in midair by using an electromagnet. For sensing the position of the hanging object, i'm using 2 ratiometric hall effect sensors above & below the electromagnet. If the object is near to electromagnet(by the signals of sensors), i need to control the intensity of electromagnet by PWM signals to move it down & in the same way if the object that is hanging is moving away from the electromagnet because of increase in weight i need to pull it up to the specified position.

The gap between the electromagnet & the object(with permanant magnet) should be 1.5 -2 cm.

1) How many no. of turns in electromagnet & which thickness of magnet wire should I choose to be wound around a soft ferrite rod for a 250g weight to get suspended in midair. The permanent magnet which i'm using with the object is N52 neodymium magnet. 2)Can i directly connect this electromagnet with PWM pin? Will the arduino blowup as load is inductive? 3) How can i vary the intensities of the electromagnet according to the values from hall sensor? As arduino output is only 5v, here electromagnet takes 12v. I need a circuit for this. I want the valves & schematic diagrams for the above. I need them soon to start my project.

Please someone help me in my Project :confused: . Any help is appreciated. Thanks in advance

Hall effect sensor placement is one above the (a)electromagnet & one between (b)electromagnet and permanent magnet. Difference(b-a) between two sensors gives the valve proportional to the distance of the object from the electromagnet.

First of all:

Is it feasible?. I mean, is the (can you) shape of the magnetic shield so that it's intensiy varies in between the two magnets as to hold something (iron) there?. Is it possible to make it by hand?. (Better: would a human be able to hold it by varying the intensity if he -she- is fast enough as to control it?

Regards

Hi,

I've having a look to the link (and two other on the same subject).

I keep on thinking that the shape of magnets (magnetic field) is a key characteristic of the whole system. It reminds me a ping-pong ball floating in an air flow; I've always thought the air flow had a "cone" shape (I'm not sure).

For sure you can not give the neccesary current directly from the arduino (Not just because the load is inductive, but for the current is too big. This is not going to be the main problem, as long as there exist many amplifiers -H bridge-).

Any case: I'm not going to discourage you, but I keep thinking that the equilibrium of the "suspended" thing is not easy to achieve: From the engineering point of view it looks very unstable.

Good luck. Regards.

thank you sir for your reply. If arduino is not feasible for my project then which micro-controller would you suggest me to use in my project? and current which i need for my solenoid to levitate is 350 to 370mA. thanks again

abhiramk789: thank you sir for your reply. If arduino is not feasible for my project then which micro-controller would you suggest me to use in my project? and current which i need for my solenoid to levitate is 350 to 370mA. thanks again

It's not that Arduino isn't feasible for your project. It is (or I think it is, anyway.) However, it will require some support ("power") circuitry.

http://thesignalpath.com/blogs/2013/01/28/tutorial-and-experiments-on-magnetic-levitation/

I want to do exactly the same thing but with added weight & auto adjusting according to weight.