Electromagnet sizing

perhaps you may want to use a relay out of an old car.

Have a look at

http://www.harting.com/en/en/en/sol/autom/prod/mag/minisol/view/index.en.html

You find diagrams, examples, drawings.
If 1.5V magnets are not available you could take a DC/DC-converter and build your own 6V or 12V - thats a more common voltage for these parts. An advantage of this concept is that you can suck your battery cell very efficiently.

Regards
Uwe

Thanks Uwe,

I need something much smaller as I only need 50g when in contact. I also do not have the space for anything this big. I expect a core of a few mm diameter and a few mm more of fine copper should do the trick. I would like to make some prototypes and then get these custom made for me (20-50k per year.) Any suggestions anyone?

Thanks, Erik

Guest:

Is residual magnetism @ zero current a problem? If not, I'd start very simply with some cheap, standard piece of hardware (nail, bolt, etc) for a core and a few turns of enameled copper magnet wire. Limit current and size by using the smallest appropriate wire and you can avoid the waste of a dropping resistor. Once you learn how many ampere-turns are needed, things should move pretty quickly. It wouldn't be a huge development program. If the magnetism must go to near zero, you may have to use a sintered core made for chokes or transformers.

DickL

Since 'tiny' is a relative term, you need to start with the actual amount of contact area you need or can afford to use, how flat the mating surfaces are, their relative angle to one another and the direction of applied force. That said, a suggested design would look something like a wound plastic bobbin with a through hole containing an iron core with the necessary contact area and contact profile. You need to also consider the amount of physical space you can devote to the electromagnet, it's duty cycle, cooling, it's mounting, and its possible effect on any neighboring electronics. Sorry I can't offer any more without more application details.

Thanks both DickL and FKIA,

I was hoping someone would say something like "for 1,5v try about XX turns of 0,XXmm wire on about an XX diameter core." Any suggestions out there?

I'll get some very small wire, a few small sintered cores and start winding.

Thanks again, Erik

just take 0.1mm dia copper enameld wire and wound it on 2.5mm dia en 18 material if possible make bobbin for the same make 200 turns minimum and lift your 50 gms magnetic material if need more strength add more turns and v it lift fine without any problen

nayanelectronics@yahoo.co.in

arun j

I'd check out http://www.apwcoinc.com/e-magnet.php

They have an off the shelf magnet, that operates on 3V and is .5" in diameter. Might be overkill for your situation, but I have had them build custom magnets before. They might be willing to build you something smaller. Either way, they know their stuff and might be helpful.

DW