Magnetics

© Brooke Clarke 2015

Background
Description
    Field Strength
    Measuring
Applications
    Magnetic Recording
    Magnetostriction
Related
Links

Background

This is a way to collect things magnetic in the same way that the Optics or Battery pages collect those things.

Description

Field Strength

There are two areas of interest: 

Earth's magnetic filed

 Which is about 50,000 nano Tesla or 0.5 Gauss and important for things like compass determination of direction.

Permanent & Electromagnets

These develop much higher forces than the Earth's field and typically are measured by different instruments.

Measuring

There are many magnetic sensors some of which measure only the total magnitude of the magnetic field and others which measure the field in a specific direction and so have a vector output, like for a compass.

1925872 Apparatus for making magnetic tests, Hermann Peter C, Gen Electric, Sep 5, 1933 324/227 - when a ring of material can not be used.
RE?

2829338 Test transformer for ring-type magnetic cores, Lord Harold W, Gen Electric, Apr 1, 1958, 324/223, 336/220, 324/260, 324/211, 336/212, 336/73, 336/174, 336/222 -  intended for measuring strip wound cores of high permeability material.

5008621 Multiparameter magnetic inspection system with magnetic field control and plural magnetic transducers, David C. Jiles, Iowa State U, Apr 16, 1991, 324/227, 324/232, 324/243, 324/223 - many citations and references, just the test set for developing magnetostriction materials.

5012189 Method for deriving information regarding stress from a stressed ferromagnetic material, David C. Jiles Iowa State U, Apr 30, 1991, 324/209 - 

Applications

Magnetic Recording

Wire recording (Wiki) was the first type of magnetic recording.
661619 Method of recording and reproducing sounds or signals, Valdemar Poulsen, Nov 13, 1900, 360/87; 235/449; 360/136; 379/70 - for signals, messages or speech

The label on a "Webster Chicago (Wiki) Model 80-1 RMA 375" wire recorder says "This unit licensed under Armour Research Foundation patents"  So I looked for them:
2456767 Combination of magnetic transducing and erasing heads, Camras Marvin, Armour Res Found, Filed: Nov 29, 1945 Pub: Dec 21, 1948, 360/123.17, 360/121, 360/125.1, 361/151, 29/603.9 - This is for a single head where one coil is for recording/playback and the other is the erase head for a wire recorder.  Referenced by 38 other patents.

Tape recording works pretty much as wire recording except since the tape is much wider the signal to noise ratio is very much improved.  When learning how to adjust the Magnacord M1024 tape recorder I
discovered that the material being recorded acts like the bias signal and so the amount of bias depends on what's being recorded.  Very little bias is needed to record white noise whereas more bias is needed to record a single tone.

Magnetostriction (Wiki)

A lot of work was done on magnetostriction at Iowa State University, Ames Iowa and the nearby Ames Lab.

Note that magnetostriction is complementary to the piezoelectric effect.  In one case mechanical motion comes about by magnetic fields and in the other by electric fields.

Materials

Iron (Wiki) and a number of iron alloys change dimensions when a magnetic filed is applied.  This is why transformers make noise.
Nickel (Wiki) was used in W.W.II About -50 ppm
Cobalt (Wiki) highest Magnetostriction of any pure element, about 60 pm.
Metglas (Wili) - Fe81Si3.5B13.5C2 - see Magnetic Shielding & Fluxgate Core Material. don't know the coefficient
Terfenol-D
                        Rods
Terfenol-D
(Wiki) TbxDy1−xFe2 (x ~ 0.3), named after terbium, iron (Fe), Naval Ordnance Laboratory (NOL), and the D comes from dysprosium.  1000 ppm from room temperature Patent search on Tefenol-D.  Saturates at about 1 Tesla.

Galfenol (Wiki) is an alloy of iron and Gallium.  About 350 ppm in ~100 Oemagnetic field. Patent search on Galfenol.Used in the CRT-1 Sonobuoy as the hydrophone. 

There is a list of patents for the CRT-1 sonobuoy hydrophone on that web page.
942897 Apparatus for receiving submarine sounds, Thomas Alexander Garrett, William Lucas, Dec 14, 1909, 367/168; 114/21.2; 318/118; 381/180 - " We make use of the well known fact that subjecting a longitudinally magnetized nickel rod or wire to variations of longitudinal stress causes variations in its magnetization and consequently causes variations of electric current in a coil of insulated wire around the rod or wire."

Patents issued on Oct 11, 1932 in a block to G.W. Pierce all on Magnetostrictive technology

1750124 Vibratory system and method,  George W. Pierce, Filed: Jan 3, 1927, Pub: Mar 11, 1930, 331/157, 310/26, 367/168, 318/118 - based on magnetostriction w/application to ships.
2014410  Electromagnetostrictive vibrator, Pierce George W, Priority: Jan 3, 1927, Pub: Sep 17, 1935, 318/118, 367/168, 73/662 - parallel rods or tubes

The below patents reference this one.

1882393 Magnetostrictive vibrator, Washington Pierce George, Priority: Mar 23, 1928,  Pub: Oct 11, 1932, 318/118, 367/168, 601/2, 29/607 -
1882394 Magnetostrictive vibrator, Washington Pierce George, Priority: Mar 23, 1928, Pub: Oct 11, 1932, 318/118, 310/26, 307/151, 367/176, 333/201, 322/3, 367/168, 331/157, 310/15 -
1882395 Frequency indicator, George W Pierce, Priority: Dec 31, 1927, Pub: Oct 11, 1932, 324/76.49, 318/118, 331/64, 29/607, 361/182, 331/157, 367/168, 367/176, 361/206, 601/2 -
1882396 Magnetostrictive transformer, Pierce George W, Priority: Dec 31, 1927, Pub: Oct 11, 1932, 333/201, 335/215, 318/118, 336/20 -  
1882397 Magnetostrictive vibrator, George W. Pierce, Filed: Aug 17, 1928, Pub: Oct 11, 1932, 333/201, 318/118, 361/206 - Nickel-Steel rod 0.5 cm (5mm or 0.196") dia X 10 cm (100mm or 3.937") long vibrates at 21 kHz. A rod 10X longer (1 meter) vibrates at 2.1 kHz.  Iron-Chromium vibrate at 27 kHz and 2.7 kHz respectively. By adding other metals with different coefficients of temperature a net zero temperature coefficient can be obtained.  Includes equations for the frequency of some standard configurations.
1882398
Magnetostrictive vibrator, Pierce George Washington, Priority: Aug 17, 1928, Pub: Oct 11, 1932,  318/118, 361/206, 428/595, 381/190, 261/DIG.480, 428/680, 261/1, 367/168, 428/684, 601/2 -
1882399 Magnetostrictive vibrator, Washington Pierce George, Priority: Aug 17, 1928, Pub: Oct 11, 1932, 318/118, 148/312, 367/168, 324/93, 148/315, 324/76.49, 451/165, 361/206, 148/310 -
1882400 Vibratory device, Alvord Buckingham Stephen, Washington Pierce George, Oct 11, 1932, 369/146, 381/190, 367/185, 318/118 - phonograph pickup using magnetostrictive element
1882401 Loud speaker, Washington Pierce George, Priority: Aug 17, 1928, Pub: Oct 11, 1932, 381/190, 318/118, 310/26, 340/384.73, 366/127 -

1962154 Magnetostrictive vibrator, George W. Pierce (Wiki), Priority Dec 31, 1927, Pub: Jun 12, 1934, 331/157, 116/137.00A, 318/118, 367/168 -
1962155 Vibratory system and apparatus, Pierce George W, Priority: Dec 31, 1927, Pub: Jun 12, 1934, 329/347, 318/118, 330/61.00R, 310/317, 310/328 - piezo-electric crystals


2116522
Compressional wave sender and receiver, Willy Kunze, Submarine Signal Co, May 10, 1938, 367/168, 318/118, 335/215, 310/26, 29/609 -


2422425 Art of tuning magnetostrictive elements, Edward Lane Albert, Rca Corp, Jun 17, 1947, 310/26, 318/118, 367/168 -   

2249835 Magnetostrictive vibrator, Emory Lakatos, Bell Telephone Labor Inc, Jul 22, 1941, 367/168, 381/190, 156/516, 335/215, 318/118, 310/26 - closing magnetic path
2166359 Magnetostrictive device, Emory Lakatos, Bell Telephone Labor Inc, Jul 18, 1939, 333/201, 420/581, 252/62.55, 148/312, 367/168, 420/459, 310/26, 148/315, 335/215, 318/118, 367/176 - hi Q circuit elements
2170206 Electrical and electromechanical system employing magnetostrictive devices, Warren P Mason, Bell Telephone Labor Inc, Aug 22, 1939, 333/201, 381/190, 367/156, 310/26 - circuit elements & loud speaker + submarine sound projector.

2984819 Magnetostrictive transducer, Miller Laymon N Cambridge, MA, Sec of Navy,  Filed: Jul 14 (17 year delay) 1944, Pub:   May 16, 1961 - 18 citations
4907209 Low frequency sound transducer, Martin Marietta Corporation, Mar 6, 1990, 367/168, 310/26, 367/156 -

8155344 Vehicle speaker, Toyota, Dec 23, 2008, 381/86, -  magnetostrictive vibrator used as part of speaker system.

Submarine Signal Co. patents using the word
Magnetostrictive.

Related

3am 3 Axis Magnetometer
Aircraft Pilot's Standby Magnetic Compass
Collins PN-101 Pictorial Navigation System (gyroscope & flux valve)
CRT-1B Expendable Radio SonoBuoy (ESRB) - uses a magnetostriction (Wiki) sensor as the hydrophone  
DC Gaussmeter Model 1
    AMY6 Magnetic Polarity Tester
    GE Gauss Meter & Reference Magnet
EM_Toy Engine  Electromagnet Toy Engine
FGPat Fluxgate (& other) Patents
Helmholtz Coil
    Sensitive Research Instrument Co. Fluxmeter
    Annis M25 Pocket Magnetometer
    Cenco Scientific 79860 Dynamo Analysis Apparatus - works with Fluxmeter
HT20 2000 mT Magnetic Flux Meter
Home Built Magnetometers
HP 428 Clip-on Milliammeter Magnetometer
KVHC100FG KVH C100 Flux Gate Compass module
Magnets
Magnetometer
MC1 MC-1 Magnetic Compass Calibration Set similar to AN/ASM-344
Permanent Magnet DC Motors
Sonobuoys use magnatometers
Telegraph Telegraph Equipment, Stock Ticker, District Telegraph, Teletype, Keys, Relays, Sounders, Veedre Counter, Early Connectors, Electro-magnets
Torpedoes use magnetic exploders
Weeden-El-Mtr  Weeden DC Electro0magnetic Machine (Motor or Generator)
Wireless Driveway Monitor - STI-34100 solar power magnetometer

Links

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale