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### Topic: Electromagnet (Read 2743 times)previous topic - next topic

#### A4kash

##### Feb 19, 2013, 10:42 am
I was doing some project on magnetic levitation and was to require an electromagnet.So i was thinking og making an electromagnet which was strong enough to levitate a pliers.So how can we make such a strong electromagnet out of 9v battery?Can we use AC power supply for this purpose and and how long should be the length of the electromagnet and wire to be used?

#### Grumpy_Mike

#1
##### Feb 19, 2013, 11:00 am
You can not make such a strong magnet from a 9V battery.
You only stand a chance of levitating a small spherical object pliers is right out.
If you use AC it must be rectified into DC to keep the fielding the same direction.

#### A4kash

#2
##### Feb 19, 2013, 11:14 am

You can not make such a strong magnet from a 9V battery.
You only stand a chance of levitating a small spherical object pliers is right out.
If you use AC it must be rectified into DC to keep the fielding the same direction.

http://uzzors2k.4hv.org/index.php?page=magneticlevitation
This site has the actual project.Ok here he is using 12v and he is able to leviatate the pliers.
Among other questions what should be the length of the wire?How should we coil the wire?

#### fungus

#3
##### Feb 19, 2013, 11:25 am

http://uzzors2k.4hv.org/index.php?page=magneticlevitation
This site has the actual project.Ok here he is using 12v and he is able to leviatate the pliers.

He has a lot of amps. Amps is what counts for electromagnets, not volts. A 9V battery can only supply milliamps.

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

#### Shpaget

#4
##### Feb 19, 2013, 12:01 pm
I would scrap the idea of attraction and shift it around. It is much easier to control repulsive levitation.
You put a permanent magnet in a clear plastic tube and an electromagnet at the bottom. Repulsive force is controlled by a simple PWM, no need to monitor the position of pliers and you can simply regulate the height of the levitated magnet.

#### Docedison

#5
##### Feb 19, 2013, 12:22 pmLast Edit: Feb 19, 2013, 12:46 pm by Docedison Reason: 1
This project is do-able with an Arduino and a PID Loop I've seen several over the years. The problem is similar to keeping an object at a set temperature using several sensors.
THIS is NOT a trivial project. I would build the analog version and learn EXACTLY HOW IT WORKS FIRST.
Then start making a Digital version from the Analog version.
I would read the whole  article... These are the magnet construction details...
"Construction Details
The top detector is a reference detector and the bottom one senses when an object is in levitating position. The object detector must be level with the IR LED. The reference detector must see the IR diode at all times, even when levitating an object. The electromagnet should have maximum 15 ohms of resistance, any more and it will not be able to lift anything. Too little resistance and the transistor will have problems regulating electromagnet current and will also dissipate more heat. When constructing an electromagnet there are two things to remember. Magnetic force is proportional to the number of turns and current. So when using copper wire the magnetic force is roughly proportional to the square of the power dissipated in it, for all practical use. In my coil I used 70 meters of 0.45mm magnet wire. The coil can be wound on almost any ferrous metal rod if you're not concerned with efficiency. Remember that keeping the surface area of the face small will keep the object centered better. Constructing the circuit correctly is easiest if built in two parts; part 1 with the detectors and first op-amp to make sure the output swings when an object is put in the beam, and then part 2 with the rest. This way it will be much easier to troubleshoot when it is modified and all of the sensor information is valid and it will be useful for the Digital Version.
The author goes to great detail about sensor positioning and all the other details are either in pictures or in the text.
READ IT From Start to Completion There is a lot of information but mainly for the hard bits, the rest is in pictures and I found it quite interesting.. I would love to have one for my desk. Really impressive looking.
Especially with control from an Arduino... Could make a gravity meter with data from the correction current value, If it was air current and vibration protected... with some real care it could be made to look like the pendulum in an old fashioned clock... That however would be quite advanced

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

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