Mu_metal_CRT_shields.jpg
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Summary
| Description |
English:
Magnetic shields for
cathode ray tubes
(CRTs) made of
mu metal
for use in
oscilloscopes
, from an ad by James Millen Mfg. Co. in a 1945 electronics magazine. The electron beams used in cathode ray tubes to draw on the tube's screen could be deflected by magnetic fields from transformers and other electronic components in the oscilloscope's insides. So the sides of the long CRT tube were surrounded by a shield made of mu metal. Mu metal is a high permeability nickel-iron alloy which could shield against magnetic fields by conducting the magnetic field lines around the shielded space.
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| Date | |
| Source | Retrieved June 12, 2014 from Radio News magazine, Ziff-Davis Publishing Co., New York, Vol. 33, No. 3, March 1945, p. 12 on American Radio History site |
| Author | Unknown author |
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Permission
( Reusing this file ) |
This image is from an advertisement for James Millen Mfg. Co. without a copyright notice published in a 1945 magazine. In the United States, advertisements published in collective works (magazines and newspapers) are not covered by the copyright notice for the entire collective work. (See U.S. Copyright Office Circular 3 , "Copyright Notice", page 3, "Contributions to Collective Works".) Since the advertisement was published before 1978 without a copyright notice, it falls into the public domain. |
Licensing
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This work is in the
public domain
in the United States because it was
published
in the United States between 1929 and 1977, inclusive,
without a
copyright notice
. For further explanation, see
Commons:Hirtle chart
as well as a
detailed definition
of "publication" for public art. Note that it may still be copyrighted in jurisdictions that do not apply the
rule of the shorter term
for US works (depending on the date of the author's death), such as Canada (50
p.m.a.
), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
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