@ njbuch - What you are looking for is called an electro-permanent magnet. The only product I’m aware of that’s using them currently is Google’s Project Ara phone and they are still very much under development.
@ Mr. John Smith
No problem… sorry, I thought about how that sounded afterwards and meant to go back and redo the message. I didn’t mean to sound irritated or anything, just trying to state the current situation I am looking at. I didn’t get back at redoing the post as my youngest got admitted to the hospital and time just got away from me. Personally, I would like to make one myself but that will probably come later. It sound intriguing to make one and I have always been of the mind to do it myself.
@ Samurai, no problems; how is your youngest doing?
He Is doing better. Just needs to put on weight. Went from 5lb 6oz on Friday to about 6.5 lbs now. Someone has to be with him 24/7 at the hospital, so it is a little taxing with his twin and 2 older brothers at home and work. Needless to say, projects and tinkering time is down, A LOT.
I still would like to make a gadgeteer rotary and linea magnetic encoder board. Liekt he ones from AMS.
Here is an Idea Why not use two Disk like Magnets one on each end and use a Servo to turn one magnet 360 degrees or close to repel the other magnet and turn the servo the opposite way and it will suck it in… and to release it just apply power… see the attached pictures of a really dirty demo with green wires, an MS Pen and a small servo…
stick all that above in a nice little box and call it an On Power Magnet Release Switch…
Btw now you owe me a Microsoft Pen, since I broke mine to do the demo for you :), and punched a few holes on my desk…
Edit: you can also use a regular motor instead of a servo to turn the magnet and a rubber band that would get twisted when power is applied, this way when no power the rubber band will untwist causing the motor to turn back to original position allowing the magnets to stick…
This would make it into a nice invention wouldn’t it 
cheers,
Jay.
4 Likes
nice hacking there Jay !
Great invention just there 
I have decided to go with a more stable solution for the product that I am prototyping, as I need it be small, and stable in all kinds of weather.
Unfortunately the price is higher than I hoped for, and ending at least USD50 for each magnet.
Here is the datasheet: http://www.produktinfo.conrad.com/datenblaetter/500000-524999/506161-da-01-en-PERM_ELEKTROMAGNET_ITS__PE_2025__12VDC__.pdf
Thanks for your efforts, and sorry about the holes in your desk 
@ Jay Jay, Look at that workspace! Clearly you’re experienced
Thanks guys 
now I have an excuse to buy a 3D printer… I could have just created a nice little tiny box to hold it all in a permanent seal enclosure…
maybe version 2.0 …
I wouldn’t call that experience more like a mess
cheers and good luck
Jay…
@ Jay Jay - I would call it “a complex order of cleanliness” 
[quote=“njbuch”]Unfortunately the price is higher than I hoped for, and ending at least USD50 for each magnet.
Here is the datasheet: http://www.produktinfo.conrad.com/datenblaetter/500000-524999/506161-da-01-en-PERM_ELEKTROMAGNET_ITS__PE_2025__12VDC__.pdf[/quote]
Is that $50 per magnet and about 10lb of holding force. That isn’t too bad for what I am looking at.
[quote=“Jay Jay”]
Here is an Idea Why not use two Disk like Magnets one on each end and use a Servo to turn one magnet 360 degrees or close to repel the other magnet and turn the servo the opposite way and it will suck it in… and to release it just apply power…[/quote]
That is interesting. I was thinking along those lines actually. The main difference is I was looking at diametric magnetics and turn the cylinder to reverse the polarity. Main issue I was hitting is how to mount the magnets and hold them into position. Also I think I am out of diametric magnets at the moment to test with. Also if the other system is $50, mine would cost more using a micro linear actuator. I was assuming the other device was going to be well over $150.
my version will cost way less than $5
here is version 2 a little better to see in action…
Servos cost: http://www.dx.com/p/towerpro-sg90-9g-mini-servo-with-accessories-12859#.U_d2rdh0yUk can go as low as $0.50 if bought in volume
Magnets:
http://www.dx.com/p/model-small-magnets-silver-50-pcs-pack-230260#.U_d25th0yUk
around $0.07 a piece, or 50 for $3.20
Design a nice way to package all that using AutoCad and send it out for mass production, Priceless
cheers,
Jay.
1 Like
No video. Says it is private. 
just finished uploading please try again…
cheers,
Jay,
I might have to give it a try, just for the tinkering aspect. Only thing is I need 204 of the setups and I was thinking of a “lock type” mechanism that would trigger all of them at once. The diametric might give more pull force, but they are usually more expensive and might be harder to align and mount.
I still will probably look at the $50 manufactured version though. When a +$10K droid is on the line, it just helps ease the mind. We’ll see. If I get a run and do a bulk order, and they work out, I will post in this site to see in anyone is interested.
Now… anyone have any ideas on a compact probably less than a 4"x2"x2" locking mechanism? I have a rod that needs to be held in place and released. I was thinking of something along the lines of the mechanism that holds the headrest in most cars in place… using a door lock solenoid. I will have to continue this subject on my other thread about my build.
As soon as I get some results from any of the magnetic latches I will post results here.
@ Samurai, Link to that thread. You can hold a rod in place in the same way a drill holds a drill bit in place (or a router).
https://www.ghielectronics.com/community/forum/topic?id=3584
that is an interesting idea, kind of like a chuck. Also trying to figure out and idea for being able to apply pressure to move it, that is a bigger issue as space is small and forces can get high. It is basically a large lever total droid with both legs is >225 lbs.tryingt o figure out what the body will be to see what forces are in play, but that is changing with the addition of new features in the droid.
I found another place in the USA that has something along these lines as well.
@ Samurai, Nice. I wonder how this stuff is made.
It might just similar concept I used on video on top…