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Re: Python programming

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On Friday 07 March 2014 12:29:38 Grant Edwards did opine:

> On 2014-03-07, William Ray Wing <wrw@mac.com> wrote:
> > On Mar 6, 2014, at 8:24 PM, Roy Smith <roy@panix.com> wrote:
> >>> I spotted a device on the table of the company calibration office...
> >>> 
> >>> As I recall, it was a 100A capable resistor... 0.10 OHM.
> >>> 
> >>> No idea what it was meant for; big binding posts at one end, and a
> >>> slab of sheet steel in a "W" shape (smooth curves, not sharp bends).
> >> 
> >> External shunt for an ammeter?
> > 
> > More likely a dummy load for power supply testing.
> 
> Could be.  Back when I was working on PWM controllers for golf cart
> and small car motors, we used to use steel coathangers for test loads,
> but once they got past orange and more towards yellow, they started to
> get too soft.  An appropriately dimensioned chunk of sheet steel would
> have been ideal.
> 
> > (Normally, ammeter shunts are sized to dissipate as little power as
> > possible.)
> 
> I've used chunks of coathanger for that too, but I don't think the
> resistance was stable enough over temperature to trust the results at
> higher currents.

This is really really offtopic but since its turned into war stories,
I recall one time that I needed to test a 5v 200amp supply that there were 
2 of in an old NEC Digital Video Effects unit,  I looked up the R per 1000' 
of standard romex in the various gauges & went over the Lowes and bought a 
100' roll of of 10/2.  Soldered the inside end together after striping and 
twisting it together,  It worked well, but the PSU didn't.  Made by HP back 
when they _thought_ they knew about how to build cement block sized power 
supplies. The psu went into foldback at about 20 amps.  All the bugs were 
good, nothing running warm.  Analyzing backwards in view of the curie point 
on some ferrite's being below the boiling point of water, I finally came to 
the conclusion that the ferrite in the output transformer had gone 
austenitic, eg totally non-magnetic, like it was just so much air, which is 
what many of those compounds will do if magnetized near saturation when 
they hit the curie point, and will never recover from.  HP of course didn't 
have the transformer or a replacement supply, but I found some Pioneer's 
with a suitable rating at M.P.Jones in FL and broke their hands putting a 
check for 2 of them in them, shipped yesterday.  That was in about 1997 & 
they were still in service when we turned analog tv off June 30, 2008. 

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.

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Python programming ngangsia akumbo <ngangsia@gmail.com> - 2014-02-11 16:21 -0800
  Re: Python programming Chris Angelico <rosuav@gmail.com> - 2014-02-12 12:17 +1100
  Re: Python programming Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-11 21:06 -0500
  Re: Python programming Rustom Mody <rustompmody@gmail.com> - 2014-02-11 18:46 -0800
  Re: Python programming Roy Smith <roy@panix.com> - 2014-02-11 22:02 -0500
    Re: Python programming Gene Heskett <gheskett@wdtv.com> - 2014-02-11 23:14 -0500
    Re: Python programming Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-02-12 13:41 +0000
    Re: Python programming Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-12 21:00 -0500
      Re: Python programming Grant Edwards <invalid@invalid.invalid> - 2014-02-13 02:57 +0000
        Re: Python programming Roy Smith <roy@panix.com> - 2014-02-12 22:04 -0500
          Re: Python programming Chris Angelico <rosuav@gmail.com> - 2014-02-13 14:13 +1100
            Re: Python programming Grant Edwards <invalid@invalid.invalid> - 2014-02-13 15:13 +0000
          Re: Python programming William Ray Wing <wrw@mac.com> - 2014-02-12 22:56 -0500
            Re: Python programming Dan Sommers <dan@tombstonezero.net> - 2014-02-13 05:18 +0000
          Re: Python programming Larry Martell <larry.martell@gmail.com> - 2014-02-13 03:30 -0500
            Re: Python programming John Ladasky <john_ladasky@sbcglobal.net> - 2014-03-07 10:03 -0800
              Re: Python programming Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-03-07 19:38 -0500
                Re: Python programming John Ladasky <john_ladasky@sbcglobal.net> - 2014-03-08 14:06 -0800
              Re: Python programming William Ray Wing <wrw@mac.com> - 2014-03-07 21:46 -0500
          Re: Python programming albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-03-06 02:51 +0000
            Re: Python programming Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-03-06 19:25 -0500
              Re: Python programming Roy Smith <roy@panix.com> - 2014-03-06 20:24 -0500
                Re: Python programming William Ray Wing <wrw@mac.com> - 2014-03-06 21:27 -0500
                Re: Python programming Larry Hudson <orgnut@yahoo.com> - 2014-03-06 23:56 -0800
                Re: Python programming Grant Edwards <invalid@invalid.invalid> - 2014-03-07 17:00 +0000
                Re: Python programming Gene Heskett <gheskett@wdtv.com> - 2014-03-07 12:49 -0500
  Re: Python programming Asdrúbal Iván Suárez <asdrubalivan.listas@gmail.com> - 2014-02-11 20:01 -0430
  Re: Python programming Ben Finney <ben+python@benfinney.id.au> - 2014-02-12 15:09 +1100
  Re: Python programming Larry Martell <larry.martell@gmail.com> - 2014-02-12 08:55 -0500
    Re: Python programming Roy Smith <roy@panix.com> - 2014-02-12 09:13 -0500
      Re: Python programming Larry Martell <larry.martell@gmail.com> - 2014-02-12 11:43 -0500
      Re: Python programming Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-12 21:13 -0500
  Re: Python programming Tim Delaney <timothy.c.delaney@gmail.com> - 2014-02-13 08:02 +1100
  Re: Python programming Chris Angelico <rosuav@gmail.com> - 2014-02-13 08:34 +1100
  Re: Python programming Tim Delaney <timothy.c.delaney@gmail.com> - 2014-02-13 09:57 +1100
  Re: Python programming Neil Cerutti <neilc@norwich.edu> - 2014-02-13 15:30 +0000
    Re: Python programming ngangsia akumbo <ngangsia@gmail.com> - 2014-02-14 12:29 -0800
    Re: Python programming 88888 Dihedral <dihedral88888@gmail.com> - 2014-03-05 20:05 -0800
  Re: Python programming Beowulf <offroad.adventures.engr@gmail.com> - 2014-03-05 20:19 -0800
    Re: Python programming Dan Sommers <dan@tombstonezero.net> - 2014-03-06 04:43 +0000
      Re: Python programming Roy Smith <roy@panix.com> - 2014-03-05 23:51 -0500
        Re: Python programming Grant Edwards <invalid@invalid.invalid> - 2014-03-06 14:49 +0000
    Re: Python programming Steven D'Aprano <steve@pearwood.info> - 2014-03-06 06:17 +0000
      Re: Python programming Tim Chase <python.list@tim.thechases.com> - 2014-03-06 07:09 -0600
        Re: Python programming Grant Edwards <invalid@invalid.invalid> - 2014-03-06 14:52 +0000

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