[retailer]

My first brush with meters and magnets was when I was a 14yr old in high school, my multimeter had somehow got iron particles in the magnet/coil assembly (probably when I changed the battery) I tried unsuccessfully to get them out with a pair of tweezers and eventually hit on the idea of removing the magnet to make it easier, it was a rectangular steel block that slid into the back of the movement, held in place with tabs, it all went smoothly until I replaced the magnet to find the meter had lost around 1/3 of it's sensitivity, it was my pride and joy, a 'proper' 20K ohm/volt multimeter with a switchable ranges, I was heartbroken.

Here is the circuit of a Lucas magnetiser, the 2 way switch at 38 will charge or discharge the capacitors 44&45 through resistors to the required voltage indicated on the meter 48. A push switch at 57 discharges the capacitors through the magnetising coil 26, coil polarity can be reversed with switch 53/54, a commutating diode 60 prevents possible reverse polarity from coil oscillation and also back emf both of which adversely affect the magnetisation process. Not sure what 46 is, a varistor or transient suppressor diode ?

The full patent can be found at google patents by searching for Method of magnetising the flyweights of a governor

You mentioned that the capacitors were being reverse charged did you add the, diode ? being able to charge the capacitors to a specific voltage and also reverse the coil polarity is useful as one could reverse magnetism a magnet to calibrate a magnet. The two way switch and resistors used to charge and discharge the capacitors is a very simple way to control the capacitor charge voltage, when I eventually get around to building one I think I'll use this idea.