Giorgio, be sure to use the serial connection of the coils, so you get a total wire length of 10 m, which represents a resistor for a voltage of approx. 4 V, and the remaining voltage up to 12 V must be kept on a wire resistor
I can’t really agree here Tone, to recharge a magnet you need a enourmous charge, way over short circuit, but nanoseconds before the wire burns.
For example two heavy duty cable clamps, “hitting” together for a fraction of a second.
Lots of sparks, yes, but we need that ampere rush, fast, to make it work.
I’ve used up to 3 car battery in series, 36 volts, and that is little low for neodymium magnets, is what i feel. In these cases I’ve powered 4 times, with some seconds to cool of in between.
There is also important there is good metal contact, otherwise it looses some, and an air gap could also lead to the magnet hitting the magnetizer, breaking the magnet.
Goran, you are probably right, but this wire cross-section cannot withstand more than 50A, I did a test, below is the video. Well, for a very short time, you could also drop a higher current, but I thought I would restore the magnet in the way shown in the video, when the master connects the coils for 5 seconds and taps the magnet with a small copper object.
I forgot to write that the coil represents a large resistance for short current pulses, this is actually the inductance of the coil, if I charged a large capacitor to a rather high voltage (300V), I could do it, but it would be necessary to connect a diode in between, so that the current ran in one direction only.
Goran, you are right here.
The build guide has them in parallel, but the solenoid allows for a short pulse. I could be wrong, but I thought the diodes were there to prevent back EMF, or the current generated by moving the iron (magnet to be charged) in the magnetic field, since that would create current in the coils and backfeed the battery.
Sean, when the battery drives a large current through the coil, a strong magnetic field is created, which has its own “persistence”, but when we cut off the current source from the battery, the resulting magnetic field begins to decrease, and this decrease in the density of the magnetic field again induces a current in the coil, which has the same direction as the current from the battery, if you look at the diagram, you will find that this current is completed through a diode. The coil can also be called a damper because it resists rapid changes and stifles and rounds off these changes.
I think we are both right here Tone, coils are hard things to calculate, inductance, impedance, the coils resistance against rapid changes in current. My small magneto re-magnetizer i think has 2,5-3mm copper wire, i don’t know how many turns though, it is an “elctromagnetic choke” from a BIG electric forklift charger.
I rebuilt it so the core is open, for placing magnets.
This one i run 2 car batteries, 24volt, short pulses, no resistor in series.
I have no knolidge about this but was thinking, if overheating is a problem, culd one make a coil out of soft copper pipe and hook it up to cold water tap? Like induction forges do?
yesterday was no rain in the outdoor workshop, so we dismantled some magnetos with a extractor…the cone of the impulse coupling stands very sturdy on the axle, so the extractor must use a bit of force till the cone goes off with a bang…
the spring of the impulse coupling is broken…hopely i can weld it without weaken the spring.
kristijan your idea seems very creative when thicker copper wire is not to get… when the windings not touch each other should work?..what says our experts…
tone, your magneto on your fiat tractor seems not being the original one, is it also a marelli?
only when you see a name on it without taking it off from the tractor.
seems also is a model with rotating magnet.
Giorgio, it may not be nessesery to weld it. Ususly the springs are long enaigh for the bend to be cut off and a new one made. Heated with a torch and bent, then slowly cooled down to prevent it being brittle. Its how l usualy do it.
originally it is one spring, bended in the half lenght , and than winded…
but i think, when welding not works, it can also be bended up, how you say…
maybee for fixing in the grove (and after that it stays in the grove) it is easier when it is only one piece
Giorgio, you see all the details, my Fiat has a Lucas ignition system, obviously not original, but so far it has a good spark. Shortly after buying the tractor, I noticed that it was poorly attached, well, I fixed that. Your Fiat does not have a PTO shaft and hydraulics, here are pictures of this assembly, I have not installed the hydraulics arm yet, but I have all the necessary parts. See if this assembly might fit your tractor?
cleaning the magnet rotor, i have seen a lot of thin metal sheets…
i expected one magnet block unit…
who can explain this? is it made from magnetic material thin sheets or is the magnet inside in the rotor?
made in beginning 1950 years…
Yes, laminations, thin metal sheets, reduce eddy currents. This prevents heating and conserves energy.
Yes, the magnet is in the rotor.
Here is a picture of a heavy duty capacitor that I scavenged from a wrecked frequency converter, if I charged it to 300V and let a surge of that electricity through the coil it might be enough to restore the magnet while avoiding the danger of overheating the coils, what do you think Goran, would that work?
Maybe, hard to say, needs a lot of amps, but only for very short time, and it should be good.
This is ofcourse what capacitors do best.
I think it would work?
If you need more current, you can connect capacitors in parallel, and if you are really worried about overheating, you might get away with chilling the coils first.
The formula is current = capacitance * (change in volts over time)
or i = C* (dV/dT)
The only reason why I mention it is not because anyone is actually going to do the math, but you get an idea of what you can change to increase the current.
Ahhhhh, it brings back memories. Memories of how I could never quite make Laplace Transforms (which I think would solve the problem) work right .
I do remember also that:
v=L*(di/dt) for the inductance in the coils. Might as well throw in v=i*R since there is resistance lurking in every part of the circuit. I also recall that when you combine all this, the solutions are either falling exponentials (a nice slope down in voltage and current going to zero) or sine waves (oscillations or ringing), or combinations of both. The first is probably good for magnetizers, the second, with a bit of the first, for ignition systems. If only I could figure out how to do the math. Since I’m really more of a technician than an engineer, I just build one, quick and dirty, and see what it does. Or try a circuit simulator, and avoid the smoke.
who is living proof that you can do useful work (by the grace of God) even if you don’t understand all the details. Anyone feel that way about gasifiers? Show of hands?