Need help with building electromagnet lift

MaxHeadRoom

Joined Jul 18, 2013
22,049
That is how a typical lift/material handling magnet appears, what is the resistance? Did you try it on an automotive battery or higher capacity?
Typically when used as a lift magnet, it requires a reverse polarity shot also to demag.
Max.
 

Hypatia's Protege

Joined Mar 1, 2015
3,226

Hypatia's Protege

Joined Mar 1, 2015
3,226
Does that mean, I charge the device for a long time before I can see the effect?
No... If it is indeed a PM/EM (i.e. permanent magnet/electromagnet) unit it will attract ferrous objects without power applied, whereas application of power (of correct polarity and current) will effectively 'cancel' its magnetic field. ----- On the other hand if the device is solely electromagnetic it will show only slight (residual) magnetism while non-energized, but become strongly magnetic with the application of power...

To summarize:
PM/EM: Power on => Magnetic field 'OFF'/ Power off => Magnetic field 'ON'
EM only: Power on => Magnetic field 'ON' / Power off => Magnetic field 'OFF'


BTW that's a very low capacity battery for your application!:eek:
It may not supply sufficient current for even brief operation -- in any event it won't last long... As per posts Nos 2 and 7 you should ascertain the coil resistance such that you will be cognizant of the current/power requirement..

Best regards
HP

PS: Please note that the eBay description of the magnet implies a current requirement of 250mA and, hence, a (nominal) resistance of 48 ohms...
 
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blocco a spirale

Joined Jun 18, 2008
1,546

MrChips

Joined Oct 2, 2009
22,569
In order to lift a ferro-magnetic object the magnet must come in direct contact with the object. Only then will you experience the maximum lifting capacity.
 

Thread Starter

Nagah

Joined Apr 11, 2015
5
Fabulous. This is the kind of thing my son wants to build for his science project. Do you have any tips on how to build a model version of this for his school project?
 

MaxHeadRoom

Joined Jul 18, 2013
22,049
A very simple relay for the pick up condition, you may need a short reverse demag pulse if light objects stay attracted at the point of turn off/drop.
Max.
 
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