Mechanisms of Release

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G4K-DK
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Re: Mechanisms of Release

Post by G4K-DK »

Yeah, i know they heat up... But this is getting so warm that i wont have it near my carpet, and it is even to be build into the door frame... I wouldn't sleep well if I knew I mounted a thing that got so hot inside a wooden door frame...
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cdinbonds
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Re: Mechanisms of Release

Post by cdinbonds »

Contact the manufacturer and ask if this is normal. If you don't trust it after that, send it back.
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ruru67
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Re: Mechanisms of Release

Post by ruru67 »

G4K-DK wrote:Yeah, i know they heat up... But this is getting so warm that i wont have it near my carpet, and it is even to be build into the door frame... I wouldn't sleep well if I knew I mounted a thing that got so hot inside a wooden door frame...
Well, work the numbers. If you're measuring 12V @ 500 mA, then you're dissipating 6 watts of heat. Dissipation rates depend on temperature and medium; the hotter the object is in a given medium, the higher the rate of heat dissipation, so the thing will reach an equilibrium temperature at which it is dissipating all the heat generated (in this case, 6 watts). It should reach that equilibrium within a few minutes, and stay there.

Air is a lousy conductor of heat. Wood is a bit better - thermal conductivity of wood is (very roughly) five times higher.

Anything much over 50 C is hot to the touch (as in ouch). You need to be getting over 80 before there's any real danger of burning your skin, and well over 300 before there's a risk of adjacent wood catching fire.

Believe me, 6 watts spread over a metal device that size isn't going to reach 300 degrees C in air, let alone in wood. A 12W soldering iron gets that hot, but its surface area is *way* less, and it cools down real fast when it touches anything other than air.

After all, since your measured input power (and therefore power dissipation) is exactly what the manufacturer says it ought to be, it sounds like the device is behaving according to specification. I would have difficulty believing that the specification included "burn the surrounding building down" ...
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onestrangeguy
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Re: Mechanisms of Release

Post by onestrangeguy »

This magnet was undoubtedly meant to be mounted on something, probably like a metal door frame. That frame would act as a heat sync and dissipate a lot of that heat by conducting it away from the magnet. I would suspect that mounting the magnet on something that would conduct heat away from it would help.
In addition, reducing the input voltage would reduce the power, and thus reduce reduce the heat output. Of course, this would also reduce the magnetic strength somewhat as well, but many of these devices produce more holding power than may be needed anyway, so that may not be a major concern. :hi:
There's a fine line between cuddling and holding someone down so they can't get away.
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Re: Mechanisms of Release

Post by lj »

if you are bothered about the temperature it reaches, just reduce the supply voltage. The 12 volt mag-lock I bought is very effective at 9dvc. Just reduce the voltage until you can pull it apart, then go up n voltage a bit. Use torch batteries for a guaranteed failsafe release.
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G4K-DK
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Re: Mechanisms of Release

Post by G4K-DK »

And i'm back again... got the magnet replaced, apparently was something wrong with it, the new gets warm too, but far from as much as the other.

I also noticed another thing with the other magnet, it started around 500mA then went up, and kept climbing with the temperature, the wires from the connection to the magnet ended up melted the insulation off, making the power supply switch off after shortening.

The new is reaching about the same temperature as a hard drive, so no cow on the ice there :)
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