Timeline for Question re Simple Electromagnet
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 4, 2018 at 1:53 | comment | added | Patrick Rynhart | Perfect thank you for the advice - I will start with a 6V "brick" torch battery. (An old school one, i.e. not Alkaline / Lithium.) | |
| Dec 4, 2018 at 1:51 | comment | added | PM 2Ring | If you haven't played with a home-made electromagnet before (or not for a long time), I suggest you try it with a simple battery first. And use an old-fashioned cheap carbon-zinc cell, not an alkaline. And definitely not a lithium! | |
| Dec 4, 2018 at 1:46 | comment | added | Patrick Rynhart | It's alright - I'm not going to do it right now. It's something that can wait weeks, e.g. Just trying to understand the best way to go about doing it safely. Thank you @PM2Ring for suggesting the capacitor. | |
| Dec 4, 2018 at 1:44 | comment | added | akhmeteli | @PatrickRynhart : Look, I am not comfortable with giving such safety-related advice. In my answer I relied on the results of a specific "experiment" performed by others and warned you about fire hazard. | |
| Dec 4, 2018 at 1:43 | comment | added | PM 2Ring | Probably a good idea to put a nice chunky capacitor across your power supply too. When you disconnect the power from the electromagnet you can get a substantial spike of back EMF. | |
| Dec 4, 2018 at 1:41 | comment | added | Patrick Rynhart | Thanks. And yes, I know this is simple electronics. But I just get a bit nervous putting an electrical short across my lab power supply :) .... | |
| Dec 4, 2018 at 1:39 | comment | added | PM 2Ring | A current-limited power supply is good, but it won't hurt to give it some assistance with a small resistor. And put lots of turns on your electromagnet. I assume you'll be holding this electromagnet in your bare hands, so you'll be able to feel how warm it is. ;) | |
| Dec 4, 2018 at 1:38 | comment | added | Alex Trounev | @PatrickRynhart the wire has resistance which can be measured. Voltage is known; Ohm’s law is also known. Calculate the current. | |
| Dec 4, 2018 at 1:36 | comment | added | Patrick Rynhart | I guess it's also dependent on the current.... My lab power supply allows current limits to be specified though | |
| Dec 4, 2018 at 1:34 | comment | added | Patrick Rynhart | Thanks @akhmeteli. If I limited the output voltage of my power supply to around 9V or so, and added a 1-2 Ohm resistor in series would this be safe enough ? (I did a quick google search to find that the internal resistance of a 9V battery is approximately this value.) | |
| Dec 4, 2018 at 1:28 | comment | added | akhmeteli | @PatrickRynhart : As I noted in my answer, shorting an ordinary battery, such as AA, is probably OK, but don't do that with your power supply - the voltage there can be higher and you don't know its internal resistance. | |
| Dec 4, 2018 at 1:25 | answer | added | akhmeteli | timeline score: 0 | |
| Dec 4, 2018 at 1:23 | comment | added | Patrick Rynhart | Okay, but even with insulation isn't it damaging on the battery ? The reason I ask is that I actually want to use a lab power supply as the power source - but don't fancy shorting across the terminals (and damaging my power supply). Should I add a ceramic resistor ? Or is there some property of twisting the wire like this which creates extra resistance whilst under load ? | |
| Dec 4, 2018 at 1:13 | comment | added | Alex Trounev | you need wire covered with insulation. | |
| Dec 4, 2018 at 0:50 | review | First posts | |||
| Dec 4, 2018 at 1:11 | |||||
| Dec 4, 2018 at 0:47 | history | asked | Patrick Rynhart | CC BY-SA 4.0 |