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This is pretty clever. The major improvements I'd want to make are some sort of RFID chip that deactivates the magnet when I'm close enough, instead of a fingerprint scanner. It seems like anyone who gets close enough can see the scanner, so I'd prefer to have something more invisible.

And the second thing would be just to improve the lag time between grasping the handle and the deactivation of the magnet, so I can just lean down and casually grab it, instead of having to hold it for a second before bringing it up. The more magic, the better.

Still, this is pretty awesome!

There are some ways that he could have improved the deactivation routine, but I thought the most clever thing was that he used a capacitance sensor to activate the magnet the moment the handle was touched. That had to greatly increase the battery life.

But also make it prone to discovery as the guy at the end of the video that spin the hammer out without touching the handle.

You could probably spin it out even with the magnet activated. The friction coefficient is probably too low for any realistic electromagnet to be strong enough to make it impossible to "slide" out.

Just try with a magnet on your fridge door. It's much easier to slide it around than it is to pull it away.

It's a bit of a balancing act between "magical" and "proper". Like it would be very easy to just have a third party control the electro-magnet via a remote control, and it would work perfectly in all situations as long as the third party was acting correctly. But it wouldn't really be a hammer that could only be lifted by one person.

Additionally having the hammer remain locked once he steps away would be a good improvement. It looks like it only locks when a person begins to clasp their hands around the handle.

Seems to me this is by design, to avoid wasting massive amounts of power when the hammer wasn't being grasped.

A Pro Mini draws a tiny amount of power, I'm talking tens of milliamps- he could leave this hammer somewhere for weeks probably without the batteries dying, with the occasional passerby trying and failing to pick it up. To manage that with the magnet running constantly would be impossible.

It's also a great safety mechanism, being stuck between an electromagnet and the metal sounds unpleasant, just shout at the guy stuck to not touch the handle and it will not hurt them!

I think an RFID ring worn on a finger would be the best bet for that.

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