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Originally posted by J M Fahey
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Answering a few questions.
1) My home magnetizer is single phase.
As said before, 220V rectified (which amounts to some 180V "mean/average"? (in Spanish the same word "valor medio" applies to both, depending on context) ,25 Amperes.
No, no molten copper, even less flying droplets, in spite of the 220x25=5500W rating because it has a HUGE thermal mass (some 6 lb 2 mm copper wire) and duty cycle is less than 1% : 5 seconds magnetizing , batches of 10/15 speakers tops.
Of course, if I let it "on", it would probably catch fire in less than 15 minutes ... but that amounts to some 150 speakers or more ... not in my wildest dreams.
I was not referring to filter caps, magnetizers are the world's largest choke input power supplies with a huge time constant, measured in seconds.
Puny 100Hz ripple pales before that.
In fact, current buildup is above 2 or 3 seconds (hence the 5 seconds "on" time), then I can't pull the speaker after 5 or 6 seconds until the residual current lowers enough.
Yes, it's a big inductor.
1) My home magnetizer is single phase.
As said before, 220V rectified (which amounts to some 180V "mean/average"? (in Spanish the same word "valor medio" applies to both, depending on context) ,25 Amperes.
No, no molten copper, even less flying droplets, in spite of the 220x25=5500W rating because it has a HUGE thermal mass (some 6 lb 2 mm copper wire) and duty cycle is less than 1% : 5 seconds magnetizing , batches of 10/15 speakers tops.
Of course, if I let it "on", it would probably catch fire in less than 15 minutes ... but that amounts to some 150 speakers or more ... not in my wildest dreams.
I was not referring to filter caps, magnetizers are the world's largest choke input power supplies with a huge time constant, measured in seconds.
Puny 100Hz ripple pales before that.
In fact, current buildup is above 2 or 3 seconds (hence the 5 seconds "on" time), then I can't pull the speaker after 5 or 6 seconds until the residual current lowers enough.
Yes, it's a big inductor.
For "valor medio" in Spanish, both average and mean are correct translations into English, and are used interchangeably.
I need *a ton* of capacitors not for filtering but for a capacitive discharge one.
The cap bank cabinet is small fridge size.
The cap bank cabinet is small fridge size.
If I recall, it was to you that I provided the patent number. Is this an implementation of that patent?
2) the three phase one lives at a friend's factory, who has 3x380V power.
Full wave rectified 380V has very little ripple, even if unfiltered.
I use a huge Siemens contactor, meant to start big motors, switching the **AC** side of things which is doable, switching DC would be close to impossible.
380Vx40A = 15KW but as before there's a lot of thermal mass, that machine has some 60 lbs copper tightly wound on some 400 lb core and duty cycle is also very low.
It has so much inductance that current rise is easily seen on a needle ammeter, so slow (say 5 or 6 seconds) that although max current is around 46A, we stop when the needle reaches 40A, both for uniformity and to minimize heating.
Full wave rectified 380V has very little ripple, even if unfiltered.
I use a huge Siemens contactor, meant to start big motors, switching the **AC** side of things which is doable, switching DC would be close to impossible.
380Vx40A = 15KW but as before there's a lot of thermal mass, that machine has some 60 lbs copper tightly wound on some 400 lb core and duty cycle is also very low.
It has so much inductance that current rise is easily seen on a needle ammeter, so slow (say 5 or 6 seconds) that although max current is around 46A, we stop when the needle reaches 40A, both for uniformity and to minimize heating.
If 300 Vdc causes current to rise from zero to 40 amps in 5 seconds. If I'm understanding, that's 37.5 Henrys. This is a pickup for infrasonic waves from the ionosphere.
Both coils (home and factory) have flyback diodes which make turning OFF much easier.
And both have been flawlessly in operation for 20/25 years, already lost count.
And both have been flawlessly in operation for 20/25 years, already lost count.
There is a lot of stored energy in that inductor, and it will generate whatever voltage it needs to dump the energy: 37.5/2*(40)^2 = 30,000 Joules.
Now the next BIG one is scaring me, whether brute force or CD.
Although I'm mulling making it a different shape: instead of making the big monster (I actually need the same magnetizer as JBL or EV, magnets follow Physics Laws and couldn't care less I am a pygmy compared to them) which can magnetize a finished speaker inside the shipping box, while I'll probably make a closed box magnetizer, *only* for the magnetic assembly, no frame or anything else (this reduces needed power by 80% because of the much reduced magnetic path) and later bolt the pre-magnetized assembly to the frame.
Although I'm mulling making it a different shape: instead of making the big monster (I actually need the same magnetizer as JBL or EV, magnets follow Physics Laws and couldn't care less I am a pygmy compared to them) which can magnetize a finished speaker inside the shipping box, while I'll probably make a closed box magnetizer, *only* for the magnetic assembly, no frame or anything else (this reduces needed power by 80% because of the much reduced magnetic path) and later bolt the pre-magnetized assembly to the frame.
Well, the pattern is clear: first unit has 6# of wire, second unit has 60#, so next unit needs 600#.
We're getting into a region where a capacitive discharge charger may be cheaper.
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