Groups > sci.electronics.design > #446177

Re: OT: in favour of gradualism

From	"tom" <tmiller11147@verizon.net>
Newsgroups	sci.electronics.design
Subject	Re: OT: in favour of gradualism
Date	2017-02-04 18:22 -0500
Organization	A noiseless patient Spider
Message-ID	<o75nio$3fj$1@dont-email.me> (permalink)
References	(6 earlier) <o75g67$6t9$1@dont-email.me> <tqjc9ct91aa4dopd9rvu2d96j16ss8loug@4ax.com> <o75ju9$jc7$1@dont-email.me> <o75ktq$mk7$1@dont-email.me> <o75lgn$oa3$2@dont-email.me>

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"Don Y" <blockedofcourse@foo.invalid> wrote in message 
news:o75lgn$oa3$2@dont-email.me...
> On 2/4/2017 3:36 PM, tom wrote:
>> "Don Y" <blockedofcourse@foo.invalid> wrote in message
>> news:o75ju9$jc7$1@dont-email.me...
>>> On 2/4/2017 3:02 PM, John Larkin wrote:
>>>>> You spec a 2000hr part in a power supply.  It meets the design
>>>>> specifications.
>>>>> It meets the expected lifespan of the product (e.g., clears warranty).
>>>>> But,
>>>>> realistically, you KNOW that this will result in the $200 product 
>>>>> being
>>>>> shit-canned in 2-3 years (of normal use).
>>>>
>>>> A typical aluminum electrolytic cap will have a rated lifetime of 2000
>>>> hours, and a shelf life the same. That's 80 days, totally insane. Does
>>>> Digikey stock them for hours, like dougnnuts? They actually work for
>>>> decades.
>>>
>>> The hour rating on an ecap indicates lifetime to a particular loss of
>>> capacitance AT WVDC AND OPERATING TEMPERATURE.
>>>
>>> So, spec a 105C cap in a device that is operating at an ambient of 25C
>>> with virtually no self-heating from ripple current and it will degrade
>>> at a rate ~250 times slower than that exact same component operating
>>> at a combined ambient + self-heating temperature of 100C.
>>>
>>> E.g., in a power supply where ripple currents tend to be high AND
>>> ambient temperature elevated (because other nearby components are
>>> dissipating power) and you WILL notice a marked difference in
>>> lifetimes between 2000hr components and 5000hr devices.
>>>
>>> Given that the cost (labor) of repairing damn near anything makes
>>> a $100-200 item effectively disposable, then specing a 2000hr part
>>> when you could just as easily spec a 5000hr part (without incurring
>>> HUGE cost increases IN BIG VOLUME) is far from "perfection"...
>>> regardless of how well it fits the spec and cost targets!
>>>
>>> (think: externalities)
>>
>> Exactly. Think warranty timer.
>
> Conversely, for a few pennies more, you could produce a QUALITY
> product (though often depriving yourself of a REPLACEMENT SALE
> a couple of years down the road).
>
> [But, heck, you may not even be in business, then!]

I look at it as a blessing for us old engineers that could never afford to 
personally own some very high quality test equipment. As an example, a HP 
8566B 22 GHz spectrum analyzer for a few hundred dollars because the scrap 
yard can't get it to run. Replace a few power supply caps and you have a 
wonderful instrument.

That and NVRAM chips with internal Li cells that have finally after 20+ 
years failed.

It's a strange new world.

Regards

Thread

OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 03:39 -0800
  Re: OT: in favour of gradualism Winfield Hill <hill@rowland.harvard.edu> - 2017-02-03 04:21 -0800
    Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 04:57 -0800
      Re: OT: in favour of gradualism Jon Elson <elson@pico-systems.com> - 2017-02-03 11:38 -0600
        Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 07:21 -0800
          Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 10:42 -0500
            Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 08:15 -0800
              Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 11:36 -0500
                Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 09:40 -0800
                Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 13:52 -0500
                Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 11:50 -0800
                Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:31 -0500
            Re: OT: in favour of gradualism Jon Elson <elson@pico-systems.com> - 2017-02-04 18:04 -0600
              Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:33 -0500
    Re: OT: in favour of gradualism jurb6006@gmail.com - 2017-02-03 05:00 -0800
      Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 09:03 -0800
    Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-03 09:35 -0700
      Re: OT: in favour of gradualism bill.sloman@ieee.org - 2017-02-03 09:10 -0800
      Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-03 17:18 -0800
      Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 07:24 -0800
        Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 12:34 -0700
          Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-04 12:04 -0800
          Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 12:07 -0800
            Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 14:15 -0700
              Re: OT: in favour of gradualism John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 14:02 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:19 -0700
                Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 17:36 -0500
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:46 -0700
                Re: OT: in favour of gradualism Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-04 14:56 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 16:17 -0700
                Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 18:22 -0500
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 16:55 -0700
                Re: OT: in favour of gradualism John Robertson <spam@flippers.com> - 2017-02-04 18:22 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 21:26 -0700
                Re: OT: in favour of gradualism "tom" <tmiller11147@verizon.net> - 2017-02-04 17:35 -0500
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 15:44 -0700
                Re: OT: in favour of gradualism "dcaster@krl.org" <dcaster@krl.org> - 2017-02-04 17:42 -0800
                Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:56 -0500
              Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-05 08:14 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-05 11:56 -0700
                Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-06 14:35 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-06 16:43 -0700
                Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-06 17:12 -0800
                Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-06 18:59 -0700
                Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-07 07:40 -0800
                Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-07 12:16 -0800
                Re: OT: in favour of gradualism krw@notreal.com - 2017-02-06 21:11 -0500
                Re: OT: in favour of gradualism tabbypurr@gmail.com - 2017-02-05 12:43 -0800
          Re: OT: in favour of gradualism krw@notreal.com - 2017-02-04 20:42 -0500
      Re: OT: in favour of gradualism John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 10:05 -0800
        Re: OT: in favour of gradualism Joerg <news@analogconsultants.com> - 2017-02-04 10:24 -0800
        Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 12:45 -0700
          Re: OT: in favour of gradualism "dcaster@krl.org" <dcaster@krl.org> - 2017-02-04 17:54 -0800
            Re: OT: in favour of gradualism Don Y <blockedofcourse@foo.invalid> - 2017-02-04 21:45 -0700

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