Resistor Nomenclature

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Ed B.
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Resistor Nomenclature

Post by Ed B. » Wed Sep 24, 2003 10:45 pm

Hi. I'm new to this forum.
Although I have an electronic background - Amateur Extra class - FCC 1st Phone license - I have, all of a sudden, noticed resistor size ( ohms ) in Ray Marsten's column / schematics which confuse me.
He refers to some resistors in the following ways...
R1 = 68R R2 = 4K7 R3 = 1Mo ( see April 2003 issue ) and yet other resistors are shown as what I would normally expect, such as...
R4 = 100K R5 = 22k.
Can any of you enlighten me about the new nomenclature, its meaning and whhere/when did it start ?
Thanks for any reply.
Ed B.

Dean Huster
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Re: Resistor Nomenclature

Post by Dean Huster » Wed Sep 24, 2003 11:09 pm

Well, Ed, the "new" notation isn't all that new. The Europeans have been using that method for a long time and it's really a superior way of notation, in my opinion. Where we would note a resistor value as 4.7K ohms, they will note it as 4K7 or 4k7, where the "k" locates the decimal point as well as providing the metric prefix multiplier. So a 6M2 resistor will be 6.2M ohms; a 62K resistor will be 62K ohms; a 620K resistor will be 620K ohms. Values below 1K ohms are noted a little differently. 620 is 620 ohms; 62 or 62R0 is 62 ohms; 6R2 is 6.2 ohms; R62 is 0.62 ohms. In those cases, the R denote the decimal point and NO multiplier (X1). The U.S. military has been using the "R" notation in their resistor markings since before 1970 for sure, where you might find a power resistor marked R56 (0.56 ohms) or 2R2 (2.2 ohms).<p>The nice thing about this form of notation is that you don't have to worry about a decimal point "disappearing" as they sometimes do. Those little dots often don't make it to the page properly and the Euro method keeps you from mistaking a 6 2 K ohm resistor with a missing dot from a 6.2 K ohm resistor.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

Ed B.
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Re: Resistor Nomenclature

Post by Ed B. » Wed Sep 24, 2003 11:33 pm

Dean -
Thanks.
I'm the guy with the lighthouse flasher that you designed. They work wonderfully.
TNX
Ed B.

dyarker
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Re: Resistor Nomenclature

Post by dyarker » Thu Sep 25, 2003 12:50 am

Dean,<p>That's interesting. All this time I thought the printing company didn't have the omega character in their machine.
Dale Y

sundancer87
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Re: Resistor Nomenclature

Post by sundancer87 » Thu Sep 25, 2003 9:33 am

If I remember correctly, Nuts&Volts ran an article explaining the Eurpoean style of nomenclature.<p>However, Dean did an excellant job of splaining what it's all about.
;)

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