How much electricity would you have to run through something the size of a nail to support/restrain the weight of a person?
Lets say for electric lock hand cuffs
It's a fucking shitload of current. Think about a 120V solenoid. As beefed up and torque-y as they get, you could still push it in with your hand. You want something that would mechanically latch into place.
i think most replies are based on suspending the person from the nail via magnetism.
if however OP you intend only to use the coil magnetic to activate a latch or lock echanism a standard PP3 9v battery should be more than enough.
also depends on how mny times you wind the wire
I turned a microwave transformer into a 1770+ watt (124VAC rectified to 118VDC with 15amp breaker) electric magnet one time. For the 5 seconds the breaker lasts before tripping it can hold all my weight (210lbs) and there's no way I could break it lose at all without the power turning off. If affected light metal stuff 2 feet away and my old CRT monitor about 5 feet away. It made the house wires warm too, so I stopped playing with it.
It is true, but not as bad ass as you'd think.
Whatever the MOT came with originally with its primary coil. Which is why it wanted to fry everything including itself using rectified mains voltages. Transformers are great to take a part and use as electric magnets for lower power usages. Just remove which ever winding that doesn't suit your needs and the "I" part of the E-I frame.
I took the primary wiring off that MOT and put it on the pipe in this image and used an old PSU from a PC to power it. 5 volts 30 amps was the max that PSU could handle.
It's more dependent on the coil than the battery. I recall a science project where we were using some magnet like this that had been heavily wound. Couldn't break it under a 9v battery like that.
Fishing magnets hold something like 200 lbs, which is wild overkill for your application, and can be run from 12v DC. It would be impossible to break with hands behind back... Little leverage there.
>Anyways they sell electromagnetics for holding doors open.
They sell them for holding doors shut too.
I used to work in a school, one of the "pods" was used to hold kids with disabilities. They needed to be able to keep them from wandering off and to be able to keep the hulk tards from getting out.
Out of curiosity one day, I locked them and had my friend hold the catch release and I put a shoulder into it with a running start and I just got a sore shoulder. I'm about 200 pounds and assuming I was doing about 10mph since it was a short sprint. That means my momentum was probably just shy of 400 kg m/s.
We had to take down the magnets when one of the IT guys got stuck in there until the building was armed and he set off the motion sensor and the police responded.
I looked at the locks and they were rated for 2000lbs and were "prison grade". Made me laugh since they were being used to keep children in. No idea where the number comes from though.