products offers magneto magnetizer products. About 16% of these are mobile phone bags & cases, 7% are magnetic materials, and 5% are. “Could you send plans and drawings for the magneto charger in your article?” This was the most frequent inquiry I had after my November GEM article on . I would like to build a magnet charger like the one John Rex wrote in the January I have been a full time Magneto Restorer/Repairman for quite a number of.
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Take a look at some of the equipment we use in our workshop for magneto servicing and overhauls.
Magneto Chargers collection on eBay!
The internal magnetiser can be used for most jobs, and we prefer it because maggneto is so efficient, effective and quick and easy to use. The internal magnetiser is based on a design by Allan Hurst which was published many years ago in the Velocette Owners’ Club’s Fishtail magazine. Our version of it has a cylindrical core containing an iron cross-piece around which several hundred turns of lacquered copper wire are wound.
The mganeto and winding are encapsulated in car body-filler between two aluminium end pieces. The ends of the winding are connected to terminals mounted on one of the end pieces.
In use, the core is inserted into the magneto body so that the iron cross-piece extends between the magnetic pole pieces inside the magneto body. The core is plugged into a mains-powered box containing a large capacitor, a rectifier circuit, a voltmeter, a push-button switch and some ancillary bits and pieces. When the button is pressed, the capacitor is charged from the mains through the rectifier to a voltage shown on the voltmeter which levels out at just under V. When the button is subsequently released, the capacitor is discharged through the core winding.
That causes a very strong magnetic field to flow in a loop through the core’s cross-piece, one of the magneto’s pole pieces, the magneto’s magnet, the other pole piece and back to the cross-piece. The magnetic field is a pulse of very short duration while the capacitor discharges.
Building a heavy duty magnet charger
When ‘topping-up’ a magnet only one pulse is required. If charging a magnet that is completely demagnetised, or when flipping the polarity of a magnet, we usually use two or three pulses. Lucas K2FC If a magneto’s magnet is driven fully into saturation so that it achieves its full strength, its strength will drop, soon after it is put to use in the magneto, to a maximum operating level. Most Lucas magnetos are designed so that if the magnet does not have some sort of keeper such as the magneto armatureits magnet strength does not fall significantly below the maximum operating level.
So, for these Lucas magnetos, after we have charged the magnet, we can simply remove the magneto magneyizer from the internal magnetiser’s core, and then fit the magneto’s armature.
BTH KC1 With BTH magnetos, on the other hand, to prevent a significant drop in the magneetizer operating level below the maximum, the magneto does require some sort of keeper to be in place all the time between charging the magnet and getting the armature back inside the magneto. Conveniently, the magnetic pole pieces of BTH magnetos are directly accessible from the outside. Therefore, for BTH magnetos, we fit an external keeper to the magneto while we are removing the internal magnetiser’s core and replacing it with the magneto’s armature.
The external keeper is conveniently and simply provided by the large vice in the workshop. With all credit to Allan Hurst assuming he was the first to conceive of the ‘internal’ magnetiser for rotating-coil magnetosits great advantages are: The external magnetiser in our workshop has a frame and coils of conventional design.
In the photo above, it is shown with an RB M1 magneto that has an armature diameter of just under 2″, slightly too small for our smaller internal magnetiser core.
By comparison with the internal magnetiser, the magnetic path length through the external magnetiser externally of the magneto from one side of the magneto to the other is many times longer. All of this means that a far greater magnetising force is needed to achieve the required magnetic flux density at the magnet. Moreover, the sides of magnetos like the Lucas K2F are magneti, and so the magnetiser needs concave jaws in order to avoid more air gap.
The dynamo saddle of the MO1 is concave, and so the magnetiser needs a convex jaw in order to fit it properly. Nowadays we only use the external magnetiser if magnetiser can’t use the internal magnetisers. Brightspark Magnetos Ltd disclaims responsibility for any errors in the translations.
We use two different types of magnetiser for charging the magnets of rotating-coil magnetos: If a magneto’s mangeto is driven fully into saturation so that it achieves its full strength, its strength will drop, soon after it is put to use in the magneto, to a maximum operating level.
With BTH magnetos, on the other hand, magnfto prevent a significant drop in the magnetic operating level below the maximum, the magneto does require some sort of keeper to be in place all the time between charging the magnet and getting the armature back inside the magneto.