Groups > sci.electronics.design > #453619

Re: A resistor network with a curious property

From	rickman <gnuarm@gmail.com>
Newsgroups	sci.electronics.design
Subject	Re: A resistor network with a curious property
Date	2017-03-25 18:57 -0400
Organization	A noiseless patient Spider
Message-ID	<ob6sek$u40$1@dont-email.me> (permalink)
References	<oav7t0$99t$1@dont-email.me> <fa6cf46a-88c5-4437-9d71-b3c33f130141@googlegroups.com>

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On 3/23/2017 8:53 AM, Wanderer wrote:
> On Wednesday, March 22, 2017 at 9:23:30 PM UTC-4, Tim Williams wrote:
>> https://www.seventransistorlabs.com/Images/DistAttenuator.png
>>
>> Solved by minimization... should like to come up with the equation that
>> generates it, though.
>>
>> Tim
>>
>> --
>> Seven Transistor Labs, LLC
>> Electrical Engineering Consultation and Contract Design
>> Website: http://seventransistorlabs.com
>
> I don't get it.
>
> def resnet():
>     Rs =  [0.00,
>            4.975589275,
>            407.4288442,
>            6.288703772,
>            312.41813304,
>            8.53980209,
>            217.7050614,
>            13.27885061,
>            123.4502975,
>            29.4024347,
>            32.35807277,
>            633.5919372,
>            54.12833875]
>
>     Rnode = [0]
>     Rsum =  Rs[12]
>     j = 5
>     for i in range(10,0,-2):
>         Rsum += Rs[i+1]
>         Rsum = (Rsum * Rs[i])/(Rsum +Rs[i])
>         Rnode.append(Rsum)
>         print "Resistance after V%d is %.6f" % (j, Rsum)
>         j -=1
>     Rsum += Rs[1]
>     Rnode.append(Rsum)
>     print "Resistance after V0 is %.6f" % (Rsum)
>     print Rnode
>     print
>
>     Rratio = []
>     for i in range(1,6,1):
>         Rratio.append(Rnode[i]/Rnode[i+1])
>         print "V%d = V%d * %.4f" % (i, i-1, Rnode[i]/Rnode[i+1])
>     print Rratio
>     print
>
>     Rrat = 1.0
>     for i in range(5):
>         Rrat *= Rratio[i]
>         print "V%d = V0 * %.4f" % (i+1, Rrat)
>
>
>
>
> The Output is:
>
> Resistance after V5 is 30.904002
> Resistance after V4 is 40.514692
> Resistance after V3 is 43.135126
> Resistance after V2 is 44.340819
> Resistance after V1 is 45.033405
> Resistance after V0 is 50.008994
> [0, 30.904002007769993, 40.51469234494225, 43.135126236666615, 44.34081927349529, 45.03340519870456, 50.008994473704554]
>
> V1 = V0 * 0.7628
> V2 = V1 * 0.9393
> V3 = V2 * 0.9728
> V4 = V3 * 0.9846
> V5 = V4 * 0.9005
> [0.7627850594212391, 0.9392505802035443, 0.9728085079034753, 0.9846206183575656, 0.9005061124031152]
>
> V1 = V0 * 0.7628
> V2 = V0 * 0.7164
> V3 = V0 * 0.6970
> V4 = V0 * 0.6862
> V5 = V0 * 0.6180

What happened to Vout?

I'd use a spread sheet for this.  Spread sheets are pretty functional 
and easy to do.

-- 

Rick C

Thread

A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-22 20:23 -0500
  Re: A resistor network with a curious property George Herold <gherold@teachspin.com> - 2017-03-22 19:11 -0700
    Re: A resistor network with a curious property George Herold <gherold@teachspin.com> - 2017-03-22 19:49 -0700
      Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-22 23:43 -0500
    Re: A resistor network with a curious property Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-23 10:56 -0400
      Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 02:15 -0500
  Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-22 22:24 -0400
  Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-22 23:05 -0400
    Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-22 23:44 -0500
      Re: A resistor network with a curious property Jasen Betts <jasen@xnet.co.nz> - 2017-03-23 07:20 +0000
  Re: A resistor network with a curious property Robert Baer <robertbaer@localnet.com> - 2017-03-22 19:48 -0800
    Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-22 23:47 -0500
  Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 21:20 -0700
    Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-22 23:55 -0500
      Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-23 01:15 -0400
        Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 02:41 -0500
          Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-25 09:45 -0400
      Re: A resistor network with a curious property Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-23 09:16 +0000
        Re: A resistor network with a curious property Martin Brown <'''newspam'''@nezumi.demon.co.uk> - 2017-03-23 14:51 +0000
      Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-23 08:41 -0700
        Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 03:30 -0500
          Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 09:25 -0700
          Re: A resistor network with a curious property George Herold <gherold@teachspin.com> - 2017-03-25 09:59 -0700
            Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 15:25 -0500
    Re: A resistor network with a curious property Winfield Hill <hill@rowland.harvard.edu> - 2017-03-23 12:38 -0700
  Re: A resistor network with a curious property "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-03-23 06:41 +0000
  Re: A resistor network with a curious property Wanderer <wanderer@dialup4less.com> - 2017-03-23 05:53 -0700
    Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-23 13:41 -0400
    Re: A resistor network with a curious property rickman <gnuarm@gmail.com> - 2017-03-25 18:57 -0400
  Re: A resistor network with a curious property Jon Elson <jmelson@wustl.edu> - 2017-03-23 14:28 -0500
    Re: A resistor network with a curious property tabbypurr@gmail.com - 2017-03-23 20:59 -0700
      Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 09:27 -0700
    Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 02:58 -0500
      Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 09:31 -0700
        Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-25 15:32 -0500
          Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 13:54 -0700
            Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-25 17:26 -0400
              Re: A resistor network with a curious property "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-03-26 02:51 -0500
                Re: A resistor network with a curious property bitrex <bitrex@de.lete.earthlink.net> - 2017-03-26 12:18 -0400
            Re: A resistor network with a curious property whit3rd <whit3rd@gmail.com> - 2017-03-25 16:11 -0700
              Re: A resistor network with a curious property John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-26 11:36 -0700
    Re: A resistor network with a curious property rickman <gnuarm@gmail.com> - 2017-03-25 18:57 -0400
  Re: A resistor network with a curious property bloggs.fredbloggs.fred@gmail.com - 2017-03-24 09:08 -0700

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