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Re: A resistor network with a curious property

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"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message 
news:qgq7dc5p2oroebe1vbvqi8clrddjivitj5@4ax.com...
>>> Why is it not symmetric?
>>
>>You mean left to right? ...How could it?
>
> Well, symmetric with equal power dissipation per unit length would be
> a challenge.

The contrasting subjective experiences of "challenge" seen in this thread 
are interesting to me.  Bitrex seems to think it's in some way intractible; 
I think it's no worse than quadratic (and some others seem to support that 
intuition); and you think it's a "challenge" (not for the given problem, 
which was solved to your satisfaction -- if it has numbers, it works -- but 
for a related problem, which is always fun to think about).

Yet for this related problem, I can instantly see why that cannot be.  (I 
have the unfair advantage of having created and solved the problem in the 
first place.  Not trying to rub it in, but I think I'd like to leave the 
answer to be puzzled out, so I won't show why, right now anyway.)

So I wonder if your sense of "challenge" is calibrated more along the lines 
of a manager -- it calls to mind some recent debacles from the crowdfunding 
world: their managers seem to well and truly believe that "we'll solve it in 
development", nevermind that what they're trying to solve happens to be 
thermodynamics itself!

Fortunately, you know better than to fight thermodynamics itself, but the 
fact remains: if it's not immediately obvious that the problem being solved 
is equivalent to thermodynamics, or causality, or something like that, then 
you want to continue pushing for that solution, as long as it might be 
possible.

It's not an indictment of your scientific knowledge, indeed it's a very 
practical, managery thing to do, to push for a solution regardless of the 
nature of the problem.  I mean very specifically that it's a "calibration of 
'challenge'".  It's not practical for a manager to have complete knowledge 
of the subproblems going into their projects, it's only their duty to make 
sure they get solved.  And, if it should happen that the problems cannot be 
solved, adjust the schedule or project design to avoid that pitfall.

I just think it's interesting to see different worldviews applied to the 
perception of a problem.


> I'm thinking about an old HP APC7 attenuator, 20 GHz or something.
> Inside looks like a sheet of glass with a really pretty blue film on
> top.

Hmm, metal thin film, perhaps?  Or maybe a conductive plastic that happens 
to have that color.  Fun in any case.


> Here's a MiniCircuits trimmed thinfilm:
>
> https://dl.dropboxusercontent.com/u/53724080/Gear/Mini-Ckts/DSC01870.JPG
>
> https://dl.dropboxusercontent.com/u/53724080/Gear/Mini-Ckts/DSC01874.JPG
>
> https://dl.dropboxusercontent.com/u/53724080/Gear/Mini-Ckts/DSC01876.JPG
>

Looks like they did a pi attenuator, more or less, which limits power on the 
first resistor, probably.  What is that, 1/2W or 1W, something around there?

Interesting that they have a bunch of unused pads on that substrate.  I 
wonder if they use the same substrate, with different carbon tracks and 
bond-outs, for a whole slew of parts.


> What sort of power and frequency range did you have in mind? Or is
> this a theoretical exercize?
>
> Plain cheap 0805 resistors are fine to several GHz. Those values might
> be hard to get from Digikey.

Close enough values are certainly available in spades; the resulting network 
would only be good to a watt or two, though.  You could just as well make a 
couple low-dB attenuators (in the 1-10dB range) out of 1218s or 2512s, to 
get a couple watts out of chip resistors, without sacrificing much 
bandwidth.

My initial concept was to use thick film power resistors (TO-220 style, and 
the like), without simply connecting them in series-parallel (which would 
worsen the frequency response).  Now that I've shown the equi-power network 
exists, it should be quite achievable to do 200-1000W with these parts, with 
good performance into the 100s of MHz.  Which is far more than anything I 
have on my project list at the moment, so I'm happy. :)

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

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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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