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Ringer Loses Magnetism When it is Disassembled

Started by Dennis Markham, March 29, 2009, 02:45:17 PM

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Dennis Markham

I'm going to try and upload a pdf file of a document that was written by a member of the T.C.I., Jorge Amely.  You have seen postings with links to some of Jorge's beautifully restored telephones.  Jorge is an electrical engineer.   Using his scientific background he conducted a test of a Western Electric C4A ringer in an effort to determine if disassembling parts of the ringer would effect performance.  Prior to his testing he and I had both been removing the ringer's coil and I had even removed the small bar-stock magnet to allow for cleaning.  As it turns out we were doing more harm than good.  A couple of the ringers lost some strength and a couple barely work afterward.  

I thought I would post this here initially so that there could be some discussion if desired.  It can be moved to the technical section later.

Just click the link below and the document will open using the Adobe reader.


bingster

There's no need to bring Orville and Wilbur into this.

Thanks for the info, Dennis.  I think we all assume that if it went together in the first place, then we can take it apart and put it back with no problems.  This shows that such is not always the case.
= DARRIN =



BDM


--Brian--

St Clair Shores, MI

Dan/Panther

whood a thunked ?
Isn't a ringer just an electro magnet, and wouldn't any magnetism just be ambient from the charging of the coils in proximity to the metal frame parts. I would like to measure a N.O.S. ringer that had never been charged to see if the same applies.

D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

benhutcherson

Quote from: Dan/Panther on March 29, 2009, 04:40:22 PM
whood a thunked ?
Isn't a ringer just an electro magnet, and wouldn't any magnetism just be ambient from the charging of the coils in proximity to the metal frame parts. I would like to measure a N.O.S. ringer that had never been charged to see if the same applies.

D/P

The C-type ringers have both a permanent magnet(I think that it's just a basic Alnico rod) and electromagnet. Normally, the clapper is held in one position by the permanent magnet, although it's being fought all the time by the bias spring.

When the ringer is activated, the polarity of the electromagnet changes every half cycle, or 40 times a second(20 hz AC). Half the time, the electromagnet reinforces the flux of the permanent magnet, and half the time it cancels it out. This is what causes the clapper to move back and forth.

BDM

Interesting to say the least. I know magnets lose flux over time. I was always told to leave a magnet sticking to a metal surface for storage. Ever notice those old horseshoe magnets manufactured by "GENERAL" of England, came with a slab of steel? That was to keep the magnetic flux strong during storage and shipment. So, you remove it after 40 or 50 years, and it suffers a loss right away. Something it cannot regain.

Thanks Dennis

--Brian--

St Clair Shores, MI

benhutcherson

If the magnets are Alnico, which I strongly suspect they are, it's relatively easy to regenerate them with a strong magnetic field.

Dan/Panther

Quote from: benhutcherson on March 29, 2009, 07:56:52 PM
If the magnets are Alnico, which I strongly suspect they are, it's relatively easy to regenerate them with a strong magnetic field.

Would the energizing of the coils upon ringing recharge the magnets field ?
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

benhutcherson

Quote from: Dan/Panther on March 29, 2009, 08:16:16 PM
Quote from: benhutcherson on March 29, 2009, 07:56:52 PM
If the magnets are Alnico, which I strongly suspect they are, it's relatively easy to regenerate them with a strong magnetic field.

Would the energizing of the coils upon ringing recharge the magnets field ?
D/P

No, because you need a flux of a relatively constant intensity and direction.

Due to the fact that the coils are powered by AC, the flux is changing in both intensity and direction. If, however, you were to power a ringer coil on DC for a few minutes, it might regenerate the magnet.

Dan/Panther

I have an extra Flux capacitor, could I use that ? ;D

D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

bingster

As long as it's not a black beauty flux capacitor.  They're just junk.
= DARRIN =



AtomicEraTom

If you want your phone to go back to the future, a flux capacitor would be ideal!
I am a lineman for the county and I drive the main roads. Searchin' in the sun for another overload.  I hear you singin' in the wires, I can hear you through the whine, and the Witchita Lineman is still on the line.

Dan/Panther

I have a 55/500 that looks suprisingly good for it's age, I just wonder HHMMMMM?
No couldn't be.
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

McHeath

QuoteWould the energizing of the coils upon ringing recharge the magnets field ?

and

QuoteNo, because you need a flux of a relatively constant intensity and direction.

Wow, pretty soon we will be telling Lt. LaForge to reconfigure the lateral sensor pallet to scan for neutrinos in a narrow alpha wave. 

AtomicEraTom

Quote from: Dan/Panther on March 30, 2009, 01:25:09 PM
I have a 55/500 that looks suprisingly good for it's age, I just wonder HHMMMMM?
No couldn't be.
D/P

Hahaha D/P!!  You're killing me!!!
I am a lineman for the county and I drive the main roads. Searchin' in the sun for another overload.  I hear you singin' in the wires, I can hear you through the whine, and the Witchita Lineman is still on the line.