Use of units

Discussion in 'General Electronics Chat' started by uwezi, Jun 5, 2012.

  1. uwezi

    Thread Starter New Member

    Jun 5, 2012
    I have been recommending the Lessons in Electric Circuits to friends and students in the past, but yesterday I - again after quite a while - had a look into Chapter 6 myself.

    The use of units in this chapter needs to be revised, because it is inconsequent and partly wrong. I have no general objections against the use of imperial units (inches, wire gauge,...) though even the USA now strongly recommend the use of SI- or metric units. Everyone with this field of interest from outside the USA should be able to convert inches to meters and look up wire gauge tables...

    My comments mainly refer to section 8 about the 555-timer circuits.
    At some places in the source code a μ from a Windows keyboard has been inserted, which is not correctly transferred to neither the HTML, nor the LaTeX-PDF code.

    The SI-prefix for kilo (=1000) is a small k, not a capital K, i.e. it has to be kΩ and not KΩ.

    The SI-unit for current is the A (ampère) with a capital A and not a small a as consequently used at least in section 8.

  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    Hm, what does "Lessons in Electric Circuits" have to do with Allaboutcircuits?
    I think you should contact Tony R. Kuphaldtn as mentioned on the top of the page about that site.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    In the USA the convention is capital K for kilo when referring to ohms. I believe Europe uses small k, and they use the unit as a decimal point. So:

    In the USA, 1,200 ohms gets written as 1.2K (ohms implied from context)

    In Europe 1,200 ohms gets written as 1k2 (ohms implied from context)

    Europe people feel free to correct this. Otherwise, it is what it is and you ain't gonna change it.
  4. atferrari

    AAC Fanatic!

    Jan 6, 2004
    For my own work I use capital letters to anything denoting a multiple of the unit for the parameter in question and lower case for any submultiple.

    3 Km 3 kilometers
    4 Dm 4 decameters
    3 cm 3 centimeters
    6 mm 6 milimeters

    Why they changed that everywhere is a mistery. Worked well avoiding confusion. But not now anymore.
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    I believe the proper international standard is k for kilo and K for Kelvin, as for 1.2k vs 1k2 I don't know if that is a proper standard or a popular convention. These days I'm preferring 1k2 as it removes risk of that tiny decimal point . being missed.
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
    1k2 is the "electrical standard" and definitely is not a proper number for physicists etc, but I love that microcap simulator can take numbers like that without complaints. The proper number would be 1.2kΩ, because you just can´t have a k in the middle of a number and without ohms the number is meaningless. But since we allways know in what context it is used we can safely do without it (cause you don´t get kilohenries or kilofarads everyday)