Can a growler be converted to a de-magnetiser?
 

I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.

Can a growler be converted to a de-magnetiser?
 

On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:

I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.

If the armature is not there then the inductance will be very low, and
thus the current will be very high, so the coil will likely burn out
unless it has been designed to handle the power dissipation.

I think you could limit the current through the coil (for example,
with a series electric heater element) and use it as a demagnetizer
(but it might not create a strong enough magnetic field to demagnetize
a strongly magnetized object). You could also try a series degaussing
PTC thermistor out of a CRT monitor or TV.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Can a growler be converted to a de-magnetiser?
 

Spehro Pefhany wrote:
On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:

I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.

If the armature is not there then the inductance will be very low, and
thus the current will be very high, so the coil will likely burn out
unless it has been designed to handle the power dissipation.

I think you could limit the current through the coil (for example,
with a series electric heater element) and use it as a demagnetizer
(but it might not create a strong enough magnetic field to demagnetize
a strongly magnetized object). You could also try a series degaussing
PTC thermistor out of a CRT monitor or TV.

Best regards,
Spehro Pefhany

Or operate it from a "Variac" (reg TM). Lots of generic versions. :-)
...lew...

Can a growler be converted to a de-magnetiser?
 

On Sep 29, 5:26*pm, Lew Hartswick wrote:
Spehro Pefhany wrote:
On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:

I have an old fleamarket growler for checking electric motor
armatures. *It warns not to be turned on without armature in V. *My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? *Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.

If the armature is not there then the inductance will be very low, and
thus the current will be very high, so the coil will likely burn out
unless it has been designed to handle the power dissipation.

I think you could limit the current through the coil (for example,
with a series electric heater element) and use it as a demagnetizer
(but it might not create a strong enough magnetic field to demagnetize
a strongly magnetized object). You could also try a series degaussing
PTC thermistor out of a CRT monitor or TV.

Best regards,
Spehro Pefhany

Or operate it from a "Variac" (reg TM). Lots of generic versions. :-)
* * ...lew...- Hide quoted text -

- Show quoted text -

What if I try increasing the inductance by placing something of
suitable size in the V, could there be sufficient field in the air to
be useful?

John.

Can a growler be converted to a de-magnetiser?
 

wrote:
On Sep 29, 5:26 pm, Lew Hartswick wrote:
Spehro Pefhany wrote:
On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:
I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?
Thanks, John.
If the armature is not there then the inductance will be very low, and
thus the current will be very high, so the coil will likely burn out
unless it has been designed to handle the power dissipation.
I think you could limit the current through the coil (for example,
with a series electric heater element) and use it as a demagnetizer
(but it might not create a strong enough magnetic field to demagnetize
a strongly magnetized object). You could also try a series degaussing
PTC thermistor out of a CRT monitor or TV.
Best regards,
Spehro Pefhany
Or operate it from a "Variac" (reg TM). Lots of generic versions. :-)
...lew...- Hide quoted text -

- Show quoted text -

What if I try increasing the inductance by placing something of
suitable size in the V, could there be sufficient field in the air to
be useful?

John.

You'll "use up" the field in the thing, instead of the thing you want to
demagnetize. This could result in your thing still attracting things,
which would be a bad thing. Something would have to be done, before
things got out of hand.

When you slap anything ferrous into that 'V', you complete the magnetic
circuit, and provide an easy path for the flux. Take it out, and it
takes a lot of ampere-turns to drive the flux through the gap -- this is
why the current goes up when you don't load the 'V'.

Now if you put _two_ things in the gap, then the flux will get split up
between them -- so your "thing" in the gap will steal the flux from
whatever thing you want to demagnetize. So it's best to just fling one
thing into the gap while demagnetizing.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Can a growler be converted to a de-magnetiser?
 

wrote:
I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.

I have used the Sun growler at work a number of times to demagnetize
screwdrivers and it still works OK. I put the screwdriver on the magnet
and turn it on and quickly remove the screwdriver straight up and turn
it off, all in about 1 second.

Can a growler be converted to a de-magnetiser?
 

On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:

I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Sell it on eBay and put the money in your pocket, then pick up a demag
while you're there. http://tinyurl.com/4kd7k9 about $15, delivered.

Armature testers/growlers are going for $10 to $3k.

-
If the gods had meant us to vote, they'd have given us candidates.
--------------

Can a growler be converted to a de-magnetiser?
 

wrote in message
...
I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.


Wire a light bulb into the circuit. It will work as a current limiter.

Steve R.

Can a growler be converted to a de-magnetiser?
 

In article ,
Larry Jaques wrote:

On Mon, 29 Sep 2008 13:42:11 -0700 (PDT), the renowned
wrote:

I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Sell it on eBay and put the money in your pocket, then pick up a demag
while you're there. http://tinyurl.com/4kd7k9 about $15, delivered.

Armature testers/growlers are going for $10 to $3k.

-
If the gods had meant us to vote, they'd have given us candidates.
--------------

I use an old TV Degaussing coil, similar to this one:

http://www.happcontrols.com/monitors/49055900.htm

It's great, I've had it for probably 35 years and it works wonderful on
hand tools, and is big enough to do the vise.

I hate magnetized tools... unless I purposely magnetize a screwdriver or
whatever for something special. Magnetized vise jaw inserts are much
nicer when you can quickly degauss your vise jaws once done with them.

Turn it on an arm's length away from the object/s to be demagnetized,
bring it and the object together and wave it around, then pull it back
away before releasing the switch. The whole operation only needs like 5
or 7 seconds tops. (I don't know the duty cycle of these things, but I
bet it's not long.)

In my opinion, the one in the link above is pricy. I bet if you snooped
around a serviceable used one could be had for a few bucks...

I try to keep my watch, wallet, cell phone, VOM's and the like away
during use, but have forgotten a few times with no apparent ill effects.

Once for snorts and giggles, I tried erasing a VHS tape with it... it
didn't work worth a damn.

Erik

Can a growler be converted to a de-magnetiser?
 

"Steve R." writes:


I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.


Wire a light bulb into the circuit. It will work as a current limiter.

Yes, a lamp is an excellent current limited.
Why? Its impedence varies with current....
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Can a growler be converted to a de-magnetiser?
 

Thanks for the replies and suggestions. I'll try the light bulb and I will
also experiment with a few turns, ~5-10 of #12 fire connected to the output
of a Weller type resistance heating soldering gun.
John.
~~~~~~~~~~~~~~~~~~~~~~~~
"David Lesher" wrote in message
...
"Steve R." writes:


I have an old fleamarket growler for checking electric motor
armatures. It warns not to be turned on without armature in V. My
physics has faded over the years, what will happen with an incomplete
magnetic circuit? Can this be modified to use as a de-magnetiser or
is it a piece of junk just worth the copper?

Thanks, John.


Wire a light bulb into the circuit. It will work as a current limiter.

Yes, a lamp is an excellent current limited.
Why? Its impedence varies with current....
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433


** Posted from http://www.teranews.com **

Can a growler be converted to a de-magnetiser?
 

"John Wilson" writes:

Thanks for the replies and suggestions. I'll try the light bulb and I will
also experiment with a few turns, ~5-10 of #12 fire connected to the output
of a Weller type resistance heating soldering gun.
John.

Just use the lamp. Choose one ~equal to the nameplate rating
of the growler.

When cold, the lamp will allow lots of current. But as it brightens, its
resistance goes up. So this tends to allow constant current through the
growler.



--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Can a growler be converted to a de-magnetiser?
 

"John Wilson" wrote in message
...
Thanks for the replies and suggestions. I'll try the light bulb and I
will also experiment with a few turns, ~5-10 of #12 fire connected to the
output of a Weller type resistance heating soldering gun.
John.
~~~~~~~~~~~~~~~~~~~~~~~~
** Posted from http://www.teranews.com **
My Wen 250W gun works well as is for demagnetizing screwdrivers or anything
else you can get between the posts.

Don Young