Electromagnet Troubleshooting

Hey folks,
I'm deck carp for a show with a couple electromagnets set to hold a piece of rolling scenery. The magnets have been working great but one day they stopped grabbing well so I remounted them to make better contact with the plates on the scenery. The magnets are holding better now but if the set piece isn't set perfectly when I turn them on, one of the magnets makes a low humming noise that vibrates the scenery it is mounted to. Can anyone give me some tips on troubleshooting loose/humming electromagnets? I've never used them before and Google has not been helpful.
Thanks in advance.

Teko Dumoulin said:

Hey folks,
I'm deck carp for a show with a couple electromagnets set to hold a piece of rolling scenery. The magnets have been working great but one day they stopped grabbing well so I remounted them to make better contact with the plates on the scenery. The magnets are holding better now but if the set piece isn't set perfectly when I turn them on, one of the magnets makes a low humming noise that vibrates the scenery it is mounted to. Can anyone give me some tips on troubleshooting loose/humming electromagnets? I've never used them before and Google has not been helpful.
Thanks in advance.

Click to expand...

@Teko Dumoulin My first guess, and obviously it's purely a guess as I'm not there to see it, keep the surfaces clean. Magnets will attract anything magnetic as well as dust, et al, will settle due to gravity. If your "plates" and electromagnets are in intimate contact, odds are better they'll quietly co-habitate. If they are spaced slightly apart due to dust and / or off center in either direction, they're more likely to chatter noisily like a dirty motor starter or contactor. Are your magnets powered by AC or DC? DC will likely result in quieter operation. DC doesn't need to be excessively well filtered to minimize ripple, spikes and transients as you're powering windings rather than sophisticated electronics.
Toodleoo!
Ron Hebbard.

Love to see some pictures.

Is this home brew or bought? If the latter model numbers would help.

I've always wanted to use ELectromagnets for something like this. I was always concerned, long-term, about heat build-up and just this issue, potential for noise once things began to loosen.

Teko Dumoulin said:

Hey folks,
I'm deck carp for a show with a couple electromagnets set to hold a piece of rolling scenery. The magnets have been working great but one day they stopped grabbing well so I remounted them to make better contact with the plates on the scenery. The magnets are holding better now but if the set piece isn't set perfectly when I turn them on, one of the magnets makes a low humming noise that vibrates the scenery it is mounted to. Can anyone give me some tips on troubleshooting loose/humming electromagnets? I've never used them before and Google has not been helpful.
Thanks in advance.

Click to expand...

@Teko Dumoulin Are your electromagnets designed for AC or DC operation and how are you powering them; DC or AC ? What voltage are they designed for?
Toodleoo!
Ron Hebbard.

Afraid I'm no help, but I too have always been interested in this type of application. If you could provide a little tutorial in the parts and assembly of your system, you'd surely earn some valuable Control Booth Bucks!

I'm guessing AC is getting into it since DC doesn't oscillate and it sounds like something in or near the coil is loose and vibrating. Can you take some pictures? Maybe it is a DC electromagnet and something in the transformer/rectifier feeding it failed?

To kinda give you an idea of coil vibration and maybe an idea of what's happening with your setup, Great Scott! on youtube does an interesting video about getting a microwave oven transformer to play music-

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Easy hack to minimize vibrations: VHB structural foam tape (prep surfaces with alcohol and wipe dry first). Or Gorilla foam tape. Poron lasts longer though.

Regarding heat, an alternative to pulling then de-activation is pushing activation. They could rip off some velcro or pull a permanent magnet away when the electromagnets push apart. This could also eliminate the vibrations except during the brief moment of activation.