Electromagnet

Wrap wire around an iron core and run electricity through the wire

>>60264565
/thread

File: 149368584393.jpg (70KB, 512x383px) Image search: [Google]

70KB, 512x383px

>>60264553

>>60264553
What kind of budget are we talking about?

What kind of operation? Continuous, pulsed, single- or multiuse? Shape of field? DC or AC?

If just for fun, then as instructed; an electromagnet is basically as described in your image. Loop a wire as many times as you can fit and possibly use a suitable core if needed. Iron will do nicely for starters.

Be aware of resistive losses in the coil (heat) and use safe voltages. You actually can get nasty inductive spikes when disconnecting, several times over your supply voltage.

>>60265220
>You actually can get nasty inductive spikes when disconnecting, several times over your supply voltage.
Isn't this resolved by adding a diode in parallel to the coil?

>>60264565
this and the magnet can be stronger by increasing the number of turns in the coil or by increasing the amount of current going through the wire.

>>60265292
>diode

One way to mitigate it, yes. But what kind of coil are we speaking about - and which diode? A healthy spike from just a little overengineered redneck coil will fry things (although the failure mode will quench the spike).

Another way would be a spark gap, but on smaller coils a suitable safety method is simply keeping hands off the circuit. So holding both wires on a car battery by hand is not always a good idea, but will not always kill you either. Trust me, I "know" this...

Try it out. It will teach you things!

>>60264553
it's impossible.
nobody knows how they work.

>>60265292
>One way to mitigate it, yes. But what kind of coil are we speaking about - and which diode? A healthy spike from just a little overengineered redneck coil will fry things (although the failure mode will quench the spike).
I was assuming a simple coil like the picture,of course more complex designs will require more than a single diode to prevent the discharge from reaching the supply terminals.
>So holding both wires on a car battery by hand is not always a good idea, but will not always kill you either
holding the terminals from a battery that can output 300A does not sound very safe, if you are lucky it *might* not kill you but it will launch you in the air AND your body might remember how to breath autonomously again.

>>60265714
>battery that can output 300A

Remember, that the ability to deliver amperage is not itself any dangerous thing at all. It is the voltage that makes those amperes flow. So pretty much any (everyday, limited voltage, like 12V) battery is absolutely safe to touch.

Your resistance (hands) is on the order of megaohms, so current being voltage divided by resistance, it settles somewhere in the ballpark of microamperes. You cannot even feel it, be it a small stack of coin cells or a large automotive battery.

But let us consider a coil. The resistance of a coil winding might be e.g. tens of ohms, giving a current of the order of an ampere or so. Depending on the coil the breakup voltage might be hundreds of volts. This can be clearly perceived, even by hands. This happens because the coil will try to maintain current flowing - and this current will not have anywhere to go, except your hands.

This and other phenomenon of an electric magnet can be quite fascinating. Just start moderately and give it a go. Magnetic fields are fun and playing with them is IMHO the best way to get really aware of the operation of these circuits and devices.