How to build a degausser to remove magnetism



Degaussers can be used to remove magnetism from car tires, metal beds and other places where it can be a problem for sensitive people.  This article shows how to build your own at a moderate cost.


Keywords:   degauss, how to, build degausser, de-magnetize, magnetism, how degausser works


How the degausser works

Steel and a few other metals can become magnetized, while aluminum, copper, stainless steel, plastic and most other materials cannot.  Magnets can affect sensitive people, such as when sleeping on a steel bed, or when the steel belts in automobile tires spin around.


Magnetization can be removed by a degausser, which works by sending out a very strong alternating magnetic field.  This degausser alternates the magnetic field 50 or 60 times a second, depending on the country.


When the degausser is turned on, it must be at least 50 cm (1½ ft) away from the steel it is to demagnetize.  The coil is then slowly moved towards the metal in a fluid motion.  As the coil gets closer, the metalŐs magnetization changes direction 100 or 120 times a second.  As the coil is then slowly removed again, the magnetization becomes weaker and weaker, for each change in direction of the current.


If the coil is moved abruptly, or held steady in one place, it can create a magnetic hot spot.  It is vitally important to move the coil in steady and fluid motions, without any jerky movements.


The components


For safety, this degausser runs at 12 volt AC in the coil.  The basic parts are:


coil (minimum 1 millihenry air-core, higher inductance is better)

transformer 230/12 or 120/12 volt

plastic box to contain transformer

electrical cords (2)

wire nuts (4), or similar

electrical tape


It is essential to use a high-inductance air-core coil with a heavy-duty wire.  In this example, a 12 millihenry mH coil with 18 AWG wire is used.  It was purchased from Parts Express (, which specializes in components for high-quality audio equipment.  Coils of this type can be difficult to find from regular electronics stores, look at websites catering to do-it-yourself builders of audio speakers.


The transformer is a 3 amp 120/12 volt model from Radio Shack.  Such transformers are widely available from electronic component stores.  People in countries with 230 volt electricity will need a 230/12 volt transformer.  The output voltage and amperage can be a little different than the one used here.



Drill a hole in each end of the plastic box, and stick a cable in through each hole.  Put a knot on both cables, so they cannot be pulled out again.


Find out which side of the transformer is the primary (higher voltage) and solder the leads to the cable for the electrical wall socket.


On the low-voltage secondary side, identify which two leads are for 12 volts.  Some transformers have multiple loads or terminals that allow for multiple voltages, such as 6 and 12 volts.  The transformer should come with basic instructions.  Solder the connection for the 12 volt output to the cable going to the coil.


Use wire nuts, electrical tape or other measures to ensure the exposed leads do not short out.


Then solder the coil onto the other end of the 12 volt cable.  The coil should be wrapped with electrical tape, to protect the very thin insulation on the windings.  Otherwise they will wear off and possibly short out.


This is a very simple project, which requires only basic electronic skills.  If these instructions are not sufficient, then please do not attempt this project, as you can harm yourself.


The transformer has been soldered and just needs the exposed leads to be protected
by wire nuts, before mounting in the black plastic box.


Transformer box ready to be closed.


The coil has been soldered to the 12 volt cable.


The coil has now been covered in protective electrical tape.



Someone who is electrically sensitive should not use a degausser, and should stay at least 15 ft / 5 m away when it is on.


The degaussing coil and the transformer will get hot after a few minutes.  This is normal.  Simply unplug the degausser and let it cool down, before continuing the work.


Heat Problems

If the coil heats up too fast, try to run it at 6 volts instead.  Reducing the voltage by half will also reduce the magnetic field by half, but the heat loss will be just a quarter.


If the transformer gets too hot install one with a higher amperage rating.


Using the degausser

There is a detailed article about degaussing car tires in the car section of this web site:


2014 (updated 2016)