How to Magnetize or Demagnetize Small Tools Using a Soldering Gun

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By George Dowell, K0FF

Weller soldering guns operate as a transformer with a single turn short loop secondary. A low voltage developed in the secondary loop is essentially short circuited by the copper tip. The tip is smaller in diameter than the main loop, so has higher resistance, therefore gets hot faster (Kirchhoff's Law).

Near the tip, very strong magnetic fields are created. Since they are alternating, we can do a couple of things unintended by the inventor, all non soldering related!

If an object that is capable of being magnetized is placed within the loop, the power turned on for a moment, then suddenly turned OFF, with the object held stationary, the object will become magnetized by the sudden collapsing of the magnetic field.

On the other hand if the object is already magnetized and you wish to DEmagnetize it, first apply power to the soldering gun, with the object at a distance. Then bring the object into the loop, and slowly withdraw it again, all the while, the power remains ON.

This slow decreasing of the magnetic field will effectively DEmagnetize the object.

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2 Responses to How to Magnetize or Demagnetize Small Tools Using a Soldering Gun

  1. Jim Hannon says:

    Since the magnetic field of the soldering gun is alternating an object placed in the field will be magnetized with one polarity then the other. When the object is withdrawn the amount that it is magnetized in each direction gradually decreases until it is left un-magnetized.

  2. Dave says:

    I seem to remember some people have replaced the tip of the soldering iron with a coil of heavy gauge Copper wire, to increase the magnetic effect.

    There is also the trick for an impromptu replacement of a broken tip. A bit of heavy gauge, solid Copper wire will work in a pinch (It won’t work as well as a regular tip, but it works better than nothing). The usefulness can be enhanced by smashing the center portion of the wire with a hammer, to flatten it out, before folding and mounting it.

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