Anyone major in maths? please correct this
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 26th May 2005, 12:12 PM #1 chris ma   diyAudio Member     Join Date: Sep 2001 Location: Pickering, Canada Anyone major in maths? please correct this See my calculation here: L=2.91mH C=68.2pF + 180pF=248.2pF L=2.91mH=0.0291H C=248.2pF=0.0000000002482F Rs=sqrt(L/C) Rs=sqrt(0.0291/0.0000000002482) Rs=sqrt(117244157.937147461) Rs=10827.9341 Cs=[2*pi*sqrt(LC)]/Rs Cs=[2*(22/7)*sqrt(0.0291*0.0000000002482)]/10827.9341 Cs=0.000000000156010404798 If 10^-9 = n Then Cs=1.56nF So I get Rs=10k8 Cs=1.56nF Sorry that I have only O level maths and that was grade B I got many many many years ago!! __________________ The Butcher
jackinnj
diyAudio Member

Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Re: Anyone major in maths? please correct this

Quote:
 Originally posted by chris ma See my calculation here: L=2.91mH C=68.2pF + 180pF=248.2pF L=2.91mH=0.0291H
L=0.00291H -- you missed a zero.
btw, a scientific calculator makes life a lot easier -- and the Texas Instruments version can even talk to your DVM. (I am embarrassed to say that I use an HP41 which is over 20 years old.)

four decades ago when I took physics and calculus we had to do this stuff with a book of logarithms and a slide rule.

jack

Mr Evil
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Join Date: Aug 2004
Location: Behind you
Re: Re: Anyone major in maths? please correct this

Quote:
 Originally posted by jackinnj ...I am embarrassed to say that I use an HP41 which is over 20 years old...
You should be proud, not embarassed! Not succumbing to the modern disposable mentality is one step closer to a sustainable existence. Plus old stuff is often the best

I have a not-so-old TI-86 myself, although I never use it anymore, instead preferring to use 'Virtual TI' (a TI calc emulator for Windows), since it is far faster than any real calculator.
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planet10
frugal-phile(tm)
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Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Re: Re: Anyone major in maths? please correct this

Quote:
 Originally posted by jackinnj and the Texas Instruments version can even talk to your DVM. (I am embarrassed to say that I use an HP41 which is over 20 years old.)
Hey... the HP is RPN, i can't use those other silly calculators that aren't... i'd still be using my HP25C if it hadn't gotten left in an ex's glovebox.

My HP is virtual these days (althou i have a rarely used HP (maybe 15 years old) somewhere in the lab -- needs fresh batteries)

dave
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 26th May 2005, 09:08 PM #5 jackinnj   diyAudio Member     Join Date: Apr 2002 Location: Llanddewi Brefi, NJ I told my kids I had to get an RPN calculator as my mom is Polish. I used to program little magnetic tapes -- worked out the tractrix horn formula in RPN.
planet10
frugal-phile(tm)
diyAudio Moderator

Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Quote:
 Originally posted by jackinnj -- worked out the tractrix horn formula in RPN.
I think i was using an HP11 when i figured out my 1st tractrix horn... then i did a FORTH program, now i have a Trapeze spreadsheet.

dave
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 27th May 2005, 10:44 AM #7 John Hope   diyAudio Member     Join Date: Feb 2005 Location: nr LongHope, Glos. UK RPN I am an RPN addict and simply cannot use anything else than an RPN. And I use my trusty HP32SII because it's awake INSTANTLY when I need it; I do not have to PLEASE WAIT for anything to get it's act together. __________________ At Spes Infracta __________________
jan.didden
diyAudio Member

Join Date: May 2002
Location: The great city of Turnhout, BE
Re: Re: Re: Anyone major in maths? please correct this

Quote:
 Originally posted by Mr Evil You should be proud, not embarassed! Not succumbing to the modern disposable mentality is one step closer to a sustainable existence. Plus old stuff is often the best I have a not-so-old TI-86 myself, although I never use it anymore, instead preferring to use 'Virtual TI' (a TI calc emulator for Windows), since it is far faster than any real calculator.

I can beat that. 1978 Casio fx-451 scientific calculator with Solar Cell - 27 years of calculation with zero batteries - and I have two of them!

Jan Didden
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