All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

On Monday, March 23, 2015 at 3:01:02 PM UTC-4, wrote:
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

Can you go a little bigger on the diameter? Ebay item 251422762446
is for 2 mm in dia by 1 mm thick magnets. 2 mm is bout .080 inch so drilling a 2 mm. hole thru the rod would not leave much.

I did build a pulse magnetizer way back when I was in college. I used a bunch of electrolytic caps. Charged them up to a couple hundred volts and discharged them thru a coil.

Magnetising in the length wise direction is easy. Radial is harder. I would try having two pole pieces of soft iron maybe 3/4 inch in dia and with a taper to .2 inch with the end contoured to fit the .2 dia rod. And wind a coil on each pole , connect the poles in series. and then connect them to the charged cap bank.

Dan

wrote in message
...
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod
that
is .200 in diameter in the radial direction. The area to be
magnetised
needs to be about .350" from the end of the rod. The magnetism can
be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

Do you have a demagnetizer to erase mistakes?

-jsw

On Mon, 23 Mar 2015 12:06:46 -0700, wrote:

All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

Why not take a decent magnet and simply stroke your tool a few times.
This of course magnitizes the rod.


"At the core of liberalism is the spoiled child,
miserable, as all spoiled children are, unsatisfied,
demanding, ill-disciplined, despotic and useless.
Liberalism is a philosophy of sniveling brats."
PJ O'Rourke

wrote in message
...
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod
that
is .200 in diameter in the radial direction. The area to be
magnetised
needs to be about .350" from the end of the rod. The magnetism can
be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

Use a brass pin.

fired this volley in
:

All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do.

Yup... have done. I built a simple heavy coil, good for about 50A at
110VAC. (yes, AC).

"Fuse" it with a strip of foil -- you'll have to test to get the current
to interrupt at the peak of one half-cycle of the incoming AC.

When it blows - violently - the coil will have been conducting huge
current, and it will be interrupted instantly, with an arc that lasts
through the collapse time of the field in the coil.

Works good!
Lloyd

On Mon, 23 Mar 2015 16:54:51 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do.

Yup... have done. I built a simple heavy coil, good for about 50A at
110VAC. (yes, AC).

"Fuse" it with a strip of foil -- you'll have to test to get the current
to interrupt at the peak of one half-cycle of the incoming AC.

When it blows - violently - the coil will have been conducting huge
current, and it will be interrupted instantly, with an arc that lasts
through the collapse time of the field in the coil.

Works good!
Lloyd
I didn't build it or use it, but the magnets on a couple printed
circuit axial field motors I have hanging around were pulse magnetized
to peak plux at the factory - there is a strand of #14 insulated wire
wrapped around all the magnets and the two ends are brought out of the
case. When the motor was assembled, a large pulse from a capacitor
discharge was applied to the winding to top it up. I'm told the
current used is in the thousand amp range for about a millisecond -
for a resulting 1000 amp turns magnetizing force on each magnet to
"top up" the magnets.

If the motors are dissassembled the magnets loose strength and need to
be "re-pulsed" to acheive dull design power again. Oviously they are
not neomydium magnets - possibly Alnico, but I suspect they are
Ceramic or Ferrite.

On Mon, 23 Mar 2015 12:06:46 -0700, wrote:

All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric
================
I've never built one, but here is someone that did
http://tinyurl.com/le7pnws



--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

Just use a Weller type soldering gun, the kind with the heavy copper tip that is made from a piece of about 9 or 10 gage copper wire. Hold the part in between the legs of the coil and pull the trigger. Let go of the trigger. If you stopped current flow at the peak of the sine wave you get a lot of magnetism; if closer to zero, you get less. Just try it until you get the amount you want.


example of gun:
http://www.testequipmentdepot.com/we...tguns/8200.htm

Also works for demagnetizing stuff. Pull trigger, put part in, then slowly pull part away, until part is about 2 or 3 feet away before releasing trigger.

Pete Stanaitis
--------------

F. George McDuffee writes:

On Mon, 23 Mar 2015 12:06:46 -0700, wrote:

All,

I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I
want to do. The goal is to magnetise a heat treated to 40 Rc steel
rod that is .200 in diameter in the radial direction. The area to
be magnetised needs to be about .350" from the end of the rod. The
magnetism can be pretty weak, it only needs to hold a steel sleeve
in place for a few seconds. But the end of the rod must have a very
weak magnetic strength, weak enough that it won't even hold a
straight pin. Thanks, Eric

I've never built one, but here is someone that did
http://tinyurl.com/le7pnws

Oh, I built one of those. I don't quite get the OP's question so
maybe that isn't applicable to his needs. But it does work as
advertized in the Gingery booklet.


--
Mike Spencer Nova Scotia, Canada

On 3/23/2015 9:13 PM, wrote:
Just use a Weller type soldering gun, the kind with the heavy copper tip that is made from a piece of about 9 or 10 gage copper wire. Hold the part in between the legs of the coil and pull the trigger. Let go of the trigger. If you stopped current flow at the peak of the sine wave you get a lot of magnetism; if closer to zero, you get less. Just try it until you get the amount you want.

What happens if you put a diode in series with the magnetizing loop?
Probably need another diode passing current outside the loop on the opposite
half-cycle to keep the transformer happy.
example of gun:
http://www.testequipmentdepot.com/we...tguns/8200.htm

Also works for demagnetizing stuff. Pull trigger, put part in, then slowly pull part away, until part is about 2 or 3 feet away before releasing trigger.

Pete Stanaitis
--------------

On Monday, March 23, 2015 at 12:01:02 PM UTC-7, wrote:
... to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds.

A tape head demagnetizer (kind of a wand with a power cord) can
demagnetize by slowly pulling away from the object. If, however,
one switches it off instead of pulling away, it magnetizes any object
near its tip.

So, for something this small, I'd get a tape head demagnetizer and put
it onto a foot switch AC outlet.

On Mon, 23 Mar 2015 21:13:54 -0700 (PDT),
wrote:

Just use a Weller type soldering gun, the kind with the heavy copper tip that is made from a piece of about 9 or 10 gage copper wire. Hold the part in between the legs of the coil and pull the trigger. Let go of the trigger. If you stopped current flow at the peak of the sine wave you get a lot of magnetism; if closer to zero, you get less. Just try it until you get the amount you want.


example of gun:
http://www.testequipmentdepot.com/we...tguns/8200.htm

Also works for demagnetizing stuff. Pull trigger, put part in, then slowly pull part away, until part is about 2 or 3 feet away before releasing trigger.

Pete Stanaitis
--------------
Greetings Pete,
I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if I
use one of these guns with a diode in series? If the diode can take
the current, that is.
Eric

wrote in message
...
On Mon, 23 Mar 2015 21:13:54 -0700 (PDT),
wrote:

Just use a Weller type soldering gun, the kind with the heavy copper
tip that is made from a piece of about 9 or 10 gage copper wire.
Hold the part in between the legs of the coil and pull the trigger.
Let go of the trigger. If you stopped current flow at the peak of
the sine wave you get a lot of magnetism; if closer to zero, you get
less. Just try it until you get the amount you want.


example of gun:
http://www.testequipmentdepot.com/we...tguns/8200.htm

Also works for demagnetizing stuff. Pull trigger, put part in, then
slowly pull part away, until part is about 2 or 3 feet away before
releasing trigger.

Pete Stanaitis
--------------
Greetings Pete,
I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if
I
use one of these guns with a diode in series? If the diode can take
the current, that is.
Eric

Measure the voltage on your soldering gun's terminals. Mine shows
0.38VAC operating, 0.59VAC without the element. You'll have to do some
research to find a Schottky diode with a sufficiently low forward drop
at whatever high current you need.
http://www.onsemi.com/PowerSolutions/parametrics.do

If you don't use a fairly predictable capacitor bank, do you have the
equipment to measure single high current pulses rather than guessing?

-jsw

On Wednesday, March 25, 2015 at 8:57:04 AM UTC-7, wrote:

I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if I
use one of these guns with a diode in series?

Don't do that. The low resistance of the tip is the reason the transformer
type gun gets away with a small core, and if you raise the resistance (or
put a diode in) it'll just saturate and blow a fuse.

The diode would not likely pass the 200A or so of current that the
gun tip operates with.

"whit3rd" wrote in message
...
On Wednesday, March 25, 2015 at 8:57:04 AM UTC-7, wrote:

I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if I
use one of these guns with a diode in series?

Don't do that. The low resistance of the tip is the reason the
transformer
type gun gets away with a small core, and if you raise the resistance (or
put a diode in) it'll just saturate and blow a fuse.

The diode would not likely pass the 200A or so of current that the
gun tip operates with.

A long time ago, I fooled with lasers and their power supplies because they
were the future. Until I melted a penny in the fuse box at Dad's.

Diodes able to handle the abuse I was giving were very expensive. Finally,
a guy wrote an article (~1965-66-67)on holograms in Scientific American.
He made a power supply that had a synchronous motor twirling a rotary switch
to(full wave)rectify the AC from a center tapped neon sign transformer. I
made one from his discussion and it worked great. No core saturation anymore
because the switching time was so fast - I think about 3600 rpm.
I just now went to the basement to dig in the archives (never throw anything
away) to see if I could find the copy of the magazine. I know I have it.
But where? Probably at Mom's. The power supply might be there too. If
you're interested, I'll keep looking.

Steve

On Wednesday, March 25, 2015 at 11:57:04 AM UTC-4, wrote:

--------------
Greetings Pete,
I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if I
use one of these guns with a diode in series? If the diode can take
the current, that is.
Eric

If I were doing it, I would use capacitors charged from DC supply and connected to a coil with an air core by a knife switch. The amount of magnitizing current easily adjusted by adding or removing caps and changing the DC voltage. That would be consistent. No guessing about how many cycles of AC used. The drawback is you might not have a large collection of scrap parts to use in making it.

So you might try using your MIG welder as the supply and adjust the magnetizing coil to get the right amount of magnetising force. If you happened to have a mig welder with the optional timer used for spot welding, it would work really well.

Dan

wrote in message
...
On Wednesday, March 25, 2015 at 11:57:04 AM UTC-4,
wrote:

--------------
Greetings Pete,
I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if
I
use one of these guns with a diode in series? If the diode can take
the current, that is.
Eric

If I were doing it, I would use capacitors charged from DC supply and
connected to a coil with an air core by a knife switch. The amount of
magnitizing current easily adjusted by adding or removing caps and
changing the DC voltage. That would be consistent. No guessing about
how many cycles of AC used. The drawback is you might not have a
large collection of scrap parts to use in making it.

So you might try using your MIG welder as the supply and adjust the
magnetizing coil to get the right amount of magnetising force. If you
happened to have a mig welder with the optional timer used for spot
welding, it would work really well.

Dan

=================================
I just tried magnetizing a 3/16" Allen wrench crosswise about 3/8" in
from the end with a Neodymium button magnet. The whole end of the
wrench is now magnetized pretty evenly.

I don't have an easy way to arrange two of them NS NS to concentrate
the field.

-jsw

On 2015-03-25, wrote:
On Mon, 23 Mar 2015 21:13:54 -0700 (PDT),
wrote:

Just use a Weller type soldering gun, the kind with the heavy copper
tip that is made from a piece of about 9 or 10 gage copper wire. Hold
the part in between the legs of the coil and pull the trigger. Let go
of the trigger. If you stopped current flow at the peak of the sine
wave you get a lot of magnetism; if closer to zero, you get less. Just
try it until you get the amount you want.


example of gun:
http://www.testequipmentdepot.com/we...tguns/8200.htm

Also works for demagnetizing stuff. Pull trigger, put part in, then
slowly pull part away, until part is about 2 or 3 feet away before
releasing trigger.

Pete Stanaitis
--------------
Greetings Pete,
I have a couple of these type of soldering guns. I need to have a
repeatable process because I want to make lots of parts. So what if I
use one of these guns with a diode in series? If the diode can take
the current, that is.

There are diodes which will take the current -- not exactly tiny
ones, but some which will.

However, I doubt that the voltage developed in the tip loop will
be high enough to reach the forward conduction threshold of most diodes. :-)

You could build a timer -- a 555 single-shot for example, which
could be set to the time you want -- and have it control a SSR (Solid
State Relay) to turn it on just long enough so you get a half cycle.
Your single-shot would want to be set to something like 1/120th of a
second (a half cycle of US AC current) so you you get a single short
pulse through the gun. Perhaps add a standard silicon rectifier of
appropriate current rating so you get only one half-cycle, not a full
cycle . (Lots more complex circuits possible with counting timers and
power MOSFETs controlling the current into the primary, and a sensor so
the MOSFET is always turned on at the right point in the cycle.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Monday, March 23, 2015 at 3:01:02 PM UTC-4, wrote:
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

I tried to find some information on plain carbon steel, and failed. For four hundred series stainless , the hardened condition retains a lot more magnetism than the annealed condition. Exactly what steel are you planning on using.

It also might make a difference if you have more than two poles when you magnetise the steel.

And when you say straight pin, I assume you are talking about the pins one finds among the sewing supplies.

Dan

On Wed, 25 Mar 2015 16:23:50 -0500
"SnA Higgins" wrote:

snip
Diodes able to handle the abuse I was giving were very expensive. Finally,
a guy wrote an article (~1965-66-67)on holograms in Scientific American.
He made a power supply that had a synchronous motor twirling a rotary switch
to(full wave)rectify the AC from a center tapped neon sign transformer. I
made one from his discussion and it worked great. No core saturation anymore
because the switching time was so fast - I think about 3600 rpm.
I just now went to the basement to dig in the archives (never throw anything
away) to see if I could find the copy of the magazine. I know I have it.
But where? Probably at Mom's. The power supply might be there too. If
you're interested, I'll keep looking.

Is this what you're looking for?

http://jesseenterprises.net/amsci/19...967-02-fs.html

"How to Make Holograms and Experiment with Them or Ready-Made Holograms
by C. L. Stong February, 1967"

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

"Leon Fisk" wrote in message
...
On Wed, 25 Mar 2015 16:23:50 -0500
"SnA Higgins" wrote:

snip
Diodes able to handle the abuse I was giving were very expensive.
Finally,
a guy wrote an article (~1965-66-67)on holograms in Scientific American.
He made a power supply that had a synchronous motor twirling a rotary
switch
to(full wave)rectify the AC from a center tapped neon sign transformer. I
made one from his discussion and it worked great. No core saturation
anymore
because the switching time was so fast - I think about 3600 rpm.
I just now went to the basement to dig in the archives (never throw
anything
away) to see if I could find the copy of the magazine. I know I have it.
But where? Probably at Mom's. The power supply might be there too. If
you're interested, I'll keep looking.

Is this what you're looking for?

http://jesseenterprises.net/amsci/19...967-02-fs.html

"How to Make Holograms and Experiment with Them or Ready-Made Holograms
by C. L. Stong February, 1967"

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email


Yepper! That's it.
I still haven't found anything. Mom's house is 150 miles away, and I won't
be there til Easter. SWMBO does not subscribe to "never throw anything away"
so it might be gone.

Steve

On Wed, 25 Mar 2015 19:46:37 -0700 (PDT), "
wrote:

On Monday, March 23, 2015 at 3:01:02 PM UTC-4, wrote:
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

I tried to find some information on plain carbon steel, and failed. For four hundred series stainless , the hardened condition retains a lot more magnetism than the annealed condition. Exactly what steel are you planning on using.

It also might make a difference if you have more than two poles when you magnetise the steel.

And when you say straight pin, I assume you are talking about the pins one finds among the sewing supplies.

Dan
Greetings Dan,
You are correct about the pins. I will be using probably 4340 steel
because I can get it in the heat treated condition so that it is
already pretty hard and tough. I only need two poles so that's no big
deal. I think I need to just build a C shaped magnetiser out of some
steel rod, wind some wire around it, and try discharging a cap through
it. Maybe use an old flash unit from a disposable camera since I have
a few of them in a drawer somewhere.
Eric

On 3/26/2015 10:01 AM, wrote:
On Wed, 25 Mar 2015 19:46:37 -0700 (PDT), "
wrote:

On Monday, March 23, 2015 at 3:01:02 PM UTC-4, wrote:
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

I tried to find some information on plain carbon steel, and failed. For four hundred series stainless , the hardened condition retains a lot more magnetism than the annealed condition. Exactly what steel are you planning on using.

It also might make a difference if you have more than two poles when you magnetise the steel.

And when you say straight pin, I assume you are talking about the pins one finds among the sewing supplies.

Dan
Greetings Dan,
You are correct about the pins. I will be using probably 4340 steel
because I can get it in the heat treated condition so that it is
already pretty hard and tough. I only need two poles so that's no big
deal. I think I need to just build a C shaped magnetiser out of some
steel rod, wind some wire around it, and try discharging a cap through
it. Maybe use an old flash unit from a disposable camera since I have
a few of them in a drawer somewhere.
Eric

I'd like to hear some discussion on how this might be done.

If you connect a charged cap to an inductor, you're gonna get a damped
sinusoid determined by R, L and C of the series circuit.
Isn't that exactly what happens with a demagnetizer as you move the
piece being demagnetized away?

If magnetization is a mechanical process that takes time to perform,
there should be some interaction between that process time and the frequency
of the damped oscillation??

The more I think about this the more questions I have.
Seems like you need to maintain current for some minimal time
to allow the magnetic domains to rearrange, then interrupt the
current in a manner that does not allow the inductor current to reverse?????

On Thu, 26 Mar 2015 10:46:13 -0700, mike wrote:

On 3/26/2015 10:01 AM, wrote:
On Wed, 25 Mar 2015 19:46:37 -0700 (PDT), "
wrote:

On Monday, March 23, 2015 at 3:01:02 PM UTC-4, wrote:
All,
I have been looking online and have found lots of info but I would
also like to hear from anyone here who has actually done what I want
to do. The goal is to magnetise a heat treated to 40 Rc steel rod that
is .200 in diameter in the radial direction. The area to be magnetised
needs to be about .350" from the end of the rod. The magnetism can be
pretty weak, it only needs to hold a steel sleeve in place for a few
seconds. But the end of the rod must have a very weak magnetic
strength, weak enough that it won't even hold a straight pin.
Thanks,
Eric

I tried to find some information on plain carbon steel, and failed. For four hundred series stainless , the hardened condition retains a lot more magnetism than the annealed condition. Exactly what steel are you planning on using.

It also might make a difference if you have more than two poles when you magnetise the steel.

And when you say straight pin, I assume you are talking about the pins one finds among the sewing supplies.

Dan
Greetings Dan,
You are correct about the pins. I will be using probably 4340 steel
because I can get it in the heat treated condition so that it is
already pretty hard and tough. I only need two poles so that's no big
deal. I think I need to just build a C shaped magnetiser out of some
steel rod, wind some wire around it, and try discharging a cap through
it. Maybe use an old flash unit from a disposable camera since I have
a few of them in a drawer somewhere.
Eric

I'd like to hear some discussion on how this might be done.

If you connect a charged cap to an inductor, you're gonna get a damped
sinusoid determined by R, L and C of the series circuit.
Isn't that exactly what happens with a demagnetizer as you move the
piece being demagnetized away?

If magnetization is a mechanical process that takes time to perform,
there should be some interaction between that process time and the frequency
of the damped oscillation??

The more I think about this the more questions I have.
Seems like you need to maintain current for some minimal time
to allow the magnetic domains to rearrange, then interrupt the
current in a manner that does not allow the inductor current to reverse?????
You know, I think you're right. It seems like the coil and cap would
ring. I'll have to look again at some sites that mentioned discharging
a cap into a coil to make a pulse magnetizer. I know that a lot of
magnetizers work this way, dumping current into a coil. Some turn the
coil on for a brief period using some sort of switch. Others use a
charged capacitor for the power pulse. If a cap and a rectifier are
used in series that would stop the ringing, right?
Anyway, I'll check.
Eric

On Thursday, March 26, 2015 at 5:35:00 PM UTC-4, wrote:



You know, I think you're right. It seems like the coil and cap would
ring. I'll have to look again at some sites that mentioned discharging
a cap into a coil to make a pulse magnetizer. I know that a lot of
magnetizers work this way, dumping current into a coil. Some turn the
coil on for a brief period using some sort of switch. Others use a
charged capacitor for the power pulse. If a cap and a rectifier are
used in series that would stop the ringing, right?
Anyway, I'll check.
Eric

My experience with a one microfarad foil cap charged to 2000 volts and dumped into a 0.2 ohm low inductance load showed no ringing. The cap discharged in a couple of microseconds with no ringing. Peak current was about 2000 amps. I think that electrolytic caps would have a higher equivalent series resistance and would also not ring. But I have not verified that.

Dan

On Thu, 26 Mar 2015 17:18:14 -0700 (PDT), "
wrote:

On Thursday, March 26, 2015 at 5:35:00 PM UTC-4, wrote:



You know, I think you're right. It seems like the coil and cap would
ring. I'll have to look again at some sites that mentioned discharging
a cap into a coil to make a pulse magnetizer. I know that a lot of
magnetizers work this way, dumping current into a coil. Some turn the
coil on for a brief period using some sort of switch. Others use a
charged capacitor for the power pulse. If a cap and a rectifier are
used in series that would stop the ringing, right?
Anyway, I'll check.
Eric

My experience with a one microfarad foil cap charged to 2000 volts and dumped into a 0.2 ohm low inductance load showed no ringing. The cap discharged in a couple of microseconds with no ringing. Peak current was about 2000 amps. I think that electrolytic caps would have a higher equivalent series resistance and would also not ring. But I have not verified that.

Dan
You are right. Without inductance a cap can't ring. The ring is caused
by the magnetic feild collapsing across the coil, inducing a voltage
that recharges the cap, which then discharges into the inductor - nd
it keeps repeating itself. No inductance - no ringing.

On Thu, 26 Mar 2015 17:18:14 -0700 (PDT), "
wrote:

On Thursday, March 26, 2015 at 5:35:00 PM UTC-4, wrote:



You know, I think you're right. It seems like the coil and cap would
ring. I'll have to look again at some sites that mentioned discharging
a cap into a coil to make a pulse magnetizer. I know that a lot of
magnetizers work this way, dumping current into a coil. Some turn the
coil on for a brief period using some sort of switch. Others use a
charged capacitor for the power pulse. If a cap and a rectifier are
used in series that would stop the ringing, right?
Anyway, I'll check.
Eric

My experience with a one microfarad foil cap charged to 2000 volts and dumped into a 0.2 ohm low inductance load showed no ringing. The cap discharged in a couple of microseconds with no ringing. Peak current was about 2000 amps. I think that electrolytic caps would have a higher equivalent series resistance and would also not ring. But I have not verified that.

Dan
Thanks Dan. Some real world testing is what is really needed. I don't
need a strong magnet, in fact I need a weak one. But I do need
reliable and repeatable results. I also need magnetic material that
will not lose its magnetism easily.
Cheers,
Eric

On Thursday, March 26, 2015 at 9:00:43 PM UTC-4, wrote:
. Some turn the
coil on for a brief period using some sort of switch.

A gas tube like you find in a strobe light for a camera is one type of switch. But metal to metal contact also works. But that will pit the metal.



Thanks Dan. Some real world testing is what is really needed. I don't
need a strong magnet, in fact I need a weak one. But I do need
reliable and repeatable results. I also need magnetic material that
will not lose its magnetism easily.
Cheers,
Eric

Your hard 4340 is probably a good choice.

Dan

On Thu, 26 Mar 2015 14:40:45 -0700, wrote:

snip
If a cap and a rectifier are
used in series that would stop the ringing, right?
snip
A diode correctly oriented will dump the ringing to ground,
but will allow the field to initially build. As this is a
one shot a smaller diode may be adequate. If it explodes,
use a bigger diode or several in parallel.


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"