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| Re: 1956 -- circuit reliability book [message #361408 is a reply to message #361383] |
Tue, 23 January 2018 03:18   |
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Originally posted by: AndyW
On 22/01/2018 23:56, hancock4@bbs.cpcn.com wrote:
> In 1956 McGraw Hill published a book, "Reliability Factors for
> Ground Electronic Equipment". It may be downloaded from:
> http://www.tubebooks.org/Books/Atwood/Henney%201956%20Reliab ilty%20Factors%20in%20Ground%20Electronic%20Equipment.pdf
>
> It seems to be an excellent book with a lot of good ideas on how
> to design electronic circuits for maximum reliability and
> effectiveness (as of 1956). Interesting reading.
>
> I was wondering, although obviously microprocessors have replaced
> vacuum tubes and components today are different than 60 years ago,
> what techies think of this book.
>
> Thanks.
>
> (public replies, please).
This is my particular area of expertise, my physics degree is geared
toward material physics and the physics of failure and I started working
on equipment reliability as a student in the 1980s running a 'shake and
bake' oven to reveal early-life failures in test equipment with Marconi
(Marconi CheckMATE system) before moving into design for reliability.
Broadly speaking it is out of date in terms of technology and theory.
Some of this forms the core of modern Reliability & Maintainability but
they have refined and grown considerably with time. Some is totally
outdated technology and so is not longer applicable.
The sections dealing with redundancy are still valid and the section on
human factors and interfaces is pretty much similar to today's human
factors.
A lot has changed and there is a greater emphasis on metallurgy,
soldering, pre-stressing, automation for consistency and on the physical
security of connections. There is also more emphasis on system
reliability and planned maintenance.
Early reliability was about calculating failure as precisely as possible
using calculation models such as Bell Labs, NPRD, or MIL-HBBK-217, these
are largely discredited.
There was also emphasis on preventing failures, often by the incredibly
expensive techniques of pre-stressing or 'hardening' components that
gave you confidence in terms of reliability but increased the cost by
orders of magnitude. Now we design systems to work around failures or
else to identify impending failures and schedule replacement in
down-time so as not to impact the mission.
It also goes down the wrong path of the 'bath tub curve' which has been
shown to only be valid in 14% of failures (mostly mechanical) in the
Nowlan and Heap report that basically kick-started the RCM industry.
In terms of reliability it covers the basics such as thermal stability
and cooling, vibration reduction, low humidity etc. These are still
valid today. It also covers common sense techniques such as not running
components near their limit
On the Maintainability section it is broadly similar but simpler to
today's techniques and includes a lot of common sense guides such as
consistency, simplicity etc although things have changed in the
maintainability fields these core items still remain.
Andy
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| Re: 1956 -- circuit reliability book [message #361419 is a reply to message #361408] |
Tue, 23 January 2018 08:33 |
jmfbahciv
Messages: 6173
Registered: March 2012
Karma: 0
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Senior Member |
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AndyW wrote:
> On 22/01/2018 23:56, hancock4@bbs.cpcn.com wrote:
>> In 1956 McGraw Hill published a book, "Reliability Factors for
>> Ground Electronic Equipment". It may be downloaded from:
>> http://www.tubebooks.org/Books/Atwood/Henney%201956%20Reliab ilty%20Factors%
20in%20Ground%20Electronic%20Equipment.pdf
>>
>> It seems to be an excellent book with a lot of good ideas on how
>> to design electronic circuits for maximum reliability and
>> effectiveness (as of 1956). Interesting reading.
>>
>> I was wondering, although obviously microprocessors have replaced
>> vacuum tubes and components today are different than 60 years ago,
>> what techies think of this book.
>>
>> Thanks.
>>
>> (public replies, please).
>
> This is my particular area of expertise, my physics degree is geared
> toward material physics and the physics of failure and I started working
> on equipment reliability as a student in the 1980s running a 'shake and
> bake' oven to reveal early-life failures in test equipment with Marconi
> (Marconi CheckMATE system) before moving into design for reliability.
Was that kind of work fun? How much waiting was involved? (or could
you start something up and then leave to do something else?)
/BAH
>
> Broadly speaking it is out of date in terms of technology and theory.
> Some of this forms the core of modern Reliability & Maintainability but
> they have refined and grown considerably with time. Some is totally
> outdated technology and so is not longer applicable.
>
> The sections dealing with redundancy are still valid and the section on
> human factors and interfaces is pretty much similar to today's human
> factors.
>
> A lot has changed and there is a greater emphasis on metallurgy,
> soldering, pre-stressing, automation for consistency and on the physical
> security of connections. There is also more emphasis on system
> reliability and planned maintenance.
>
> Early reliability was about calculating failure as precisely as possible
> using calculation models such as Bell Labs, NPRD, or MIL-HBBK-217, these
> are largely discredited.
>
> There was also emphasis on preventing failures, often by the incredibly
> expensive techniques of pre-stressing or 'hardening' components that
> gave you confidence in terms of reliability but increased the cost by
> orders of magnitude. Now we design systems to work around failures or
> else to identify impending failures and schedule replacement in
> down-time so as not to impact the mission.
>
> It also goes down the wrong path of the 'bath tub curve' which has been
> shown to only be valid in 14% of failures (mostly mechanical) in the
> Nowlan and Heap report that basically kick-started the RCM industry.
>
> In terms of reliability it covers the basics such as thermal stability
> and cooling, vibration reduction, low humidity etc. These are still
> valid today. It also covers common sense techniques such as not running
> components near their limit
>
> On the Maintainability section it is broadly similar but simpler to
> today's techniques and includes a lot of common sense guides such as
> consistency, simplicity etc although things have changed in the
> maintainability fields these core items still remain.
>
> Andy
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| Re: 1956 -- circuit reliability book [message #361444 is a reply to message #361408] |
Tue, 23 January 2018 16:25 |
hancock4
Messages: 6746
Registered: December 2011
Karma: 0
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Senior Member |
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On Tuesday, January 23, 2018 at 3:18:36 AM UTC-5, AndyW wrote:
[snip]
> On the Maintainability section it is broadly similar but simpler to
> today's techniques and includes a lot of common sense guides such as
> consistency, simplicity etc although things have changed in the
> maintainability fields these core items still remain.
Thanks for the information.
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| Re: 1956 -- circuit reliability book [message #361446 is a reply to message #361408] |
Tue, 23 January 2018 16:26 |
Charlie Gibbs
Messages: 5313
Registered: January 2012
Karma: 0
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Senior Member |
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On 2018-01-23, AndyW <Andy@nojunqmail.com> wrote:
> It also goes down the wrong path of the 'bath tub curve' which has been
> shown to only be valid in 14% of failures (mostly mechanical) in the
> Nowlan and Heap report that basically kick-started the RCM industry.
What has taken the place of the bathtub curve? Presumably failure rates
still vary over time, but what do you use now?
--
/~\ cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
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| Re: 1956 -- circuit reliability book [message #361490 is a reply to message #361419] |
Wed, 24 January 2018 02:58 |
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Originally posted by: AndyW
On 23/01/2018 13:33, jmfbahciv wrote:
> AndyW wrote:
>> On 22/01/2018 23:56, hancock4@bbs.cpcn.com wrote:
>>> In 1956 McGraw Hill published a book, "Reliability Factors for
>>> Ground Electronic Equipment". It may be downloaded from:
>>> http://www.tubebooks.org/Books/Atwood/Henney%201956%20Reliab ilty%20Factors%
> 20in%20Ground%20Electronic%20Equipment.pdf
>>>
>>> It seems to be an excellent book with a lot of good ideas on how
>>> to design electronic circuits for maximum reliability and
>>> effectiveness (as of 1956). Interesting reading.
>>>
>>> I was wondering, although obviously microprocessors have replaced
>>> vacuum tubes and components today are different than 60 years ago,
>>> what techies think of this book.
>>>
>>> Thanks.
>>>
>>> (public replies, please).
>>
>> This is my particular area of expertise, my physics degree is geared
>> toward material physics and the physics of failure and I started working
>> on equipment reliability as a student in the 1980s running a 'shake and
>> bake' oven to reveal early-life failures in test equipment with Marconi
>> (Marconi CheckMATE system) before moving into design for reliability.
>
> Was that kind of work fun? How much waiting was involved? (or could
> you start something up and then leave to do something else?)
The student work was basically a human robot, lots of waiting for the
ovens and shock and vibrations tables to finish then a flurry of
activity and form filling. But it was honest work and paid for my
studies and the wait time allowed me to do a lot of reading which
probably boosted my final scores.
Design for reliability was basically operating as an advisor to the
chief engineer on refining designs as pert of the design process. Basic
engineering.
Andy
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| Re: 1956 -- circuit reliability book [message #361491 is a reply to message #361446] |
Wed, 24 January 2018 03:10 |
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Originally posted by: AndyW
On 23/01/2018 21:26, Charlie Gibbs wrote:
> On 2018-01-23, AndyW <Andy@nojunqmail.com> wrote:
>
>> It also goes down the wrong path of the 'bath tub curve' which has been
>> shown to only be valid in 14% of failures (mostly mechanical) in the
>> Nowlan and Heap report that basically kick-started the RCM industry.
>
> What has taken the place of the bathtub curve? Presumably failure rates
> still vary over time, but what do you use now?
There are 6 main curves of which the bathtub is one, the vast majority
of failure curves are constant (with a rise/fall at the start for
early-life failures or break-in that can be bench stressed to remove
from deployed kit).
< http://www.maintenance.org/topic/doing-the-right-mix-of-main tenance-work>
For a population of similar items there is no real sudden rise in
probability of failures with time, the point at which the failure starts
is generally random which does go against the common belief.
Andy
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| Re: 1956 -- circuit reliability book [message #361521 is a reply to message #361491] |
Wed, 24 January 2018 13:04 |
Charlie Gibbs
Messages: 5313
Registered: January 2012
Karma: 0
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Senior Member |
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On 2018-01-24, AndyW <Andy@nojunqmail.com> wrote:
> On 23/01/2018 21:26, Charlie Gibbs wrote:
>
>> On 2018-01-23, AndyW <Andy@nojunqmail.com> wrote:
>>
>>> It also goes down the wrong path of the 'bath tub curve' which has been
>>> shown to only be valid in 14% of failures (mostly mechanical) in the
>>> Nowlan and Heap report that basically kick-started the RCM industry.
>>
>> What has taken the place of the bathtub curve? Presumably failure rates
>> still vary over time, but what do you use now?
>
> There are 6 main curves of which the bathtub is one, the vast majority
> of failure curves are constant (with a rise/fall at the start for
> early-life failures or break-in that can be bench stressed to remove
> from deployed kit).
>
> < http://www.maintenance.org/topic/doing-the-right-mix-of-main tenance-work>
Interesting article, thanks. In a world dominated by Microsoft, it's easy
to forget that there are still some organizations interested in reliability.
> For a population of similar items there is no real sudden rise in
> probability of failures with time, the point at which the failure starts
> is generally random which does go against the common belief.
This might be due to the consumer mindset, which eschews maintenance.
Buy a gadget, run it like hell until it breaks, throw it out. Lather,
rinse, repeat. Under such conditions I can see a bathtub curve as a
combination of infant mortality and wear out - both of which would be
eliminated by conscientious installation and maintenance.
--
/~\ cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
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| Re: 1956 -- circuit reliability book [message #361526 is a reply to message #361491] |
Wed, 24 January 2018 14:00 |
Gene Wirchenko
Messages: 1166
Registered: January 2012
Karma: 0
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Senior Member |
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On Wed, 24 Jan 2018 08:10:57 +0000, AndyW <Andy@nojunqmail.com> wrote:
[snip]
> For a population of similar items there is no real sudden rise in
> probability of failures with time, the point at which the failure starts
> is generally random which does go against the common belief.
Actually, I found that I did have a sudden rise in failures on
socks. I would buy a lot of one type. For a long time, none would
wear out, then the odd one, then suddenly in a period of weeks, I
would have socks wearing out sometimes more than one in a week. About
then, I would buy new socks and toss the old ones.
I have since switched to socks with a lifetime guarantee.
Sincerely,
Gene wirchenko
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| Re: 1956 -- circuit reliability book [message #361552 is a reply to message #361408] |
Wed, 24 January 2018 16:52 |
hancock4
Messages: 6746
Registered: December 2011
Karma: 0
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Senior Member |
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On Tuesday, January 23, 2018 at 3:18:36 AM UTC-5, AndyW wrote:
> There was also emphasis on preventing failures, often by the incredibly
> expensive techniques of pre-stressing or 'hardening' components that
> gave you confidence in terms of reliability but increased the cost by
> orders of magnitude. Now we design systems to work around failures or
> else to identify impending failures and schedule replacement in
> down-time so as not to impact the mission.
From reading various early 1950s writings, it seems the cost
of failure in industrial electronics was high enough to justify
the pre-stress approach, especially for vacuum tubes. For an
early computer, tracing a faulty component could take a lot of
time, especially if the failure was not total, but rather a degrade
in performance. Computers were located at customer sites, which
meant skilled technicians had to travel out (though in the earliest
days I think some techs were resident full time). There wasn't only
the cost of diagnosis and repair, but also the high cost of downtime.
Early on, they were desperately trying to improve downtime.
From the various writings it seems there was finger pointing
between the design engineers, builders, and component manufacturers.
In a way, the debate 60 years ago reminds me of the debate today
among software developers--there are some who use the latest bells
and whistles, such as in web design, while others who hold back a bit.
I suppose some engineers in the past (and the writings suggest this)
wanted to use the latest and greatest circuits, perhaps to squeeze
out some additional speed or miniaturization.
(I think the early AFIPS write-ups on bitsavers cover this.)
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| Re: 1956 -- circuit reliability book [message #361567 is a reply to message #361554] |
Wed, 24 January 2018 19:19 |
Gene Wirchenko
Messages: 1166
Registered: January 2012
Karma: 0
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Senior Member |
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On Wed, 24 Jan 2018 22:23:24 +0000, Ahem A Rivet's Shot
<steveo@eircom.net> wrote:
> On Wed, 24 Jan 2018 11:00:33 -0800
> Gene Wirchenko <genew@telus.net> wrote:
>
>> I have since switched to socks with a lifetime guarantee.
>
> Intrigued!
Sport Chek -- spelling is correct -- is a Canadian sporting goods
store. Their Icebreaker line of socks has a lifetime guarantee. They
are about $25 per pair. They are great, and I have yet to manage to
wear out a pair though not through lack of trying. They are all I
wear for socks now.
Sincerely,
Gene Wirchenko
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| Re: 1956 -- circuit reliability book [message #361581 is a reply to message #361567] |
Thu, 25 January 2018 01:53 |
Mike Spencer
Messages: 997
Registered: January 2012
Karma: 0
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Senior Member |
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Gene Wirchenko <genew@telus.net> writes:
> On Wed, 24 Jan 2018 22:23:24 +0000, Ahem A Rivet's Shot
> <steveo@eircom.net> wrote:
>
>> On Wed, 24 Jan 2018 11:00:33 -0800
>> Gene Wirchenko <genew@telus.net> wrote:
>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> Intrigued!
>
> Sport Chek -- spelling is correct -- is a Canadian sporting goods
> store. Their Icebreaker line of socks has a lifetime guarantee. They
> are about $25 per pair. They are great, and I have yet to manage to
> wear out a pair though not through lack of trying. They are all I
> wear for socks now.
Nylon/wool. My wife inherited a pair of socks knit by her grandmother
for her father from nylon/wool yarn. At 25 yrs, they were in poor
condition and wore out before 30 yrs. I had a set of thermal-knit
long-johns from nylon/wool yarn that developed holes in the knees at
25 yrs but were otherwise in fairly good condition.
It should be obvious why this fiber combo has not become popular
with companies who want to sell you useful garments.
I mostly now wear heavy, hand-knit woolen socks. With hand washing,
boots that fit properly and attention to toe nail maintenance, they
last about a decade.
--
Mike Spencer Nova Scotia, Canada
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| Re: 1956 -- circuit reliability book [message #361584 is a reply to message #361521] |
Thu, 25 January 2018 02:31 |
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Originally posted by: AndyW
On 24/01/2018 18:04, Charlie Gibbs wrote:
> This might be due to the consumer mindset, which eschews maintenance.
> Buy a gadget, run it like hell until it breaks, throw it out. Lather,
> rinse, repeat. Under such conditions I can see a bathtub curve as a
> combination of infant mortality and wear out - both of which would be
> eliminated by conscientious installation and maintenance.
The modern mindset is to accept that the failure will occur despite
preventive maintenance and instead work on making the failure
convenient. You can prevent failure by throwing money at the problem
(which is a diminishing returns situation) or you can detect an
impending failure and just schedule a replacement at the next docking
period, production line shutdown, holiday period etc.
Most items, say a bearing, will degrade over time in a regular and
predictable way* from tiny pitting in the bearing face,noise and
deflection from the bearings hitting the 'potholes' that result in heat
and vibration, through the complete collapse of the bearing. At various
stages of the collapse the impending failure is detectable through
various means such as vibration monitoring, temperature monitoring,
acoustic monitoring etc. If you can detect it early enough then you can
say with reasonable confidence how long it will be until failure.
*note that an individual bearing will show a wear-out curve but the
point at which the wear out starts is random hence the graphs for
populations of bearings show a constant failure rate flat graph.
sorry rambling on... 30 years at this and I get a bit geeky.
Andy
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| Re: 1956 -- circuit reliability book [message #361585 is a reply to message #361526] |
Thu, 25 January 2018 02:33 |
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Originally posted by: AndyW
On 24/01/2018 19:00, Gene Wirchenko wrote:
> I have since switched to socks with a lifetime guarantee.
WAIT!!!
You get guaranteed socks????
We are truly living in the future.
I have never seen such witchcraft in the UK.
Andy
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| Re: 1956 -- circuit reliability book [message #361587 is a reply to message #361565] |
Thu, 25 January 2018 03:41 |
mausg
Messages: 2483
Registered: May 2013
Karma: 0
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Senior Member |
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On 2018-01-24, Gareth's Downstairs Computer <headstone255.but.not.these.five.words@yahoo.com> wrote:
> On 24/01/2018 22:23, Ahem A Rivet's Shot wrote:
>> On Wed, 24 Jan 2018 11:00:33 -0800
>> Gene Wirchenko <genew@telus.net> wrote:
>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> Intrigued!
>>
>
> I have a wristwatch with a lifetime guarantee, for when
> it malfunctions, the main spring jumps out and slashes
> your wrist
>
!
--
greymaus.ireland.ie
Just_Another_Grumpy_Old_Man
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| Re: 1956 -- circuit reliability book [message #361588 is a reply to message #361584] |
Thu, 25 January 2018 03:50 |
mausg
Messages: 2483
Registered: May 2013
Karma: 0
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Senior Member |
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On 2018-01-25, AndyW <Andy@nojunqmail.com> wrote:
> On 24/01/2018 18:04, Charlie Gibbs wrote:
>
> predictable way* from tiny pitting in the bearing face,noise and
> deflection from the bearings hitting the 'potholes' that result in heat
> and vibration, through the complete collapse of the bearing. At various
> stages of the collapse the impending failure is detectable through
> various means such as vibration monitoring, temperature monitoring,
> acoustic monitoring etc. If you can detect it early enough then you can
> say with reasonable confidence how long it will be until failure.
>
> *note that an individual bearing will show a wear-out curve but the
> point at which the wear out starts is random hence the graphs for
> populations of bearings show a constant failure rate flat graph.
>
> sorry rambling on... 30 years at this and I get a bit geeky.
>
> Andy
I had a car trailer that used Volkswagen hubs, one of which was
making noises, so a friend told me where a beetle had been dumped,
it was there, a mess of rust, but the bearings were perfect, I wish I
could say that the trailer lasted for years, but it was stolen soon
after.
--
greymaus.ireland.ie
Just_Another_Grumpy_Old_Man
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| Re: 1956 -- circuit reliability book [message #361599 is a reply to message #361584] |
Thu, 25 January 2018 10:05 |
jmfbahciv
Messages: 6173
Registered: March 2012
Karma: 0
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Senior Member |
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AndyW wrote:
> On 24/01/2018 18:04, Charlie Gibbs wrote:
>
>> This might be due to the consumer mindset, which eschews maintenance.
>> Buy a gadget, run it like hell until it breaks, throw it out. Lather,
>> rinse, repeat. Under such conditions I can see a bathtub curve as a
>> combination of infant mortality and wear out - both of which would be
>> eliminated by conscientious installation and maintenance.
>
> The modern mindset is to accept that the failure will occur despite
> preventive maintenance and instead work on making the failure
> convenient. You can prevent failure by throwing money at the problem
> (which is a diminishing returns situation) or you can detect an
> impending failure and just schedule a replacement at the next docking
> period, production line shutdown, holiday period etc.
>
> Most items, say a bearing, will degrade over time in a regular and
> predictable way* from tiny pitting in the bearing face,noise and
> deflection from the bearings hitting the 'potholes' that result in heat
> and vibration, through the complete collapse of the bearing. At various
> stages of the collapse the impending failure is detectable through
> various means such as vibration monitoring, temperature monitoring,
> acoustic monitoring etc. If you can detect it early enough then you can
> say with reasonable confidence how long it will be until failure.
>
> *note that an individual bearing will show a wear-out curve but the
> point at which the wear out starts is random hence the graphs for
> populations of bearings show a constant failure rate flat graph.
>
> sorry rambling on... 30 years at this and I get a bit geeky.
Please continue to be geeky. This is interesting to those of us
who haven't done the work.
/BAH
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| Re: 1956 -- circuit reliability book [message #361600 is a reply to message #361526] |
Thu, 25 January 2018 10:05 |
jmfbahciv
Messages: 6173
Registered: March 2012
Karma: 0
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Senior Member |
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Gene Wirchenko wrote:
> On Wed, 24 Jan 2018 08:10:57 +0000, AndyW <Andy@nojunqmail.com> wrote:
>
> [snip]
>
>> For a population of similar items there is no real sudden rise in
>> probability of failures with time, the point at which the failure starts
>> is generally random which does go against the common belief.
>
> Actually, I found that I did have a sudden rise in failures on
> socks. I would buy a lot of one type. For a long time, none would
> wear out, then the odd one, then suddenly in a period of weeks, I
> would have socks wearing out sometimes more than one in a week. About
> then, I would buy new socks and toss the old ones.
>
> I have since switched to socks with a lifetime guarantee.
LLBean's stuff lasts a long time. The t-shirts I bought in 1995
are now fraying at the edges. I just bought another batch which
should last me a lifetime.
/BAH
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| Re: 1956 -- circuit reliability book [message #361614 is a reply to message #361383] |
Thu, 25 January 2018 13:31 |
Charlie Gibbs
Messages: 5313
Registered: January 2012
Karma: 0
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Senior Member |
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On 2018-01-25, Huge <Huge@nowhere.much.invalid> wrote:
> On 2018-01-25, AndyW <Andy@nojunqmail.com> wrote:
>
>> On 24/01/2018 19:00, Gene Wirchenko wrote:
>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> WAIT!!!
>> You get guaranteed socks????
>> We are truly living in the future.
>>
>> I have never seen such witchcraft in the UK.
>
> And it appears you can't get them here. Every time I find a favourite
> sock, I buy a dozen pairs, but by the time they've worn out, they're
> no longer made, so I have to buy random socks until I find another
> favourite. As a result, I have a drawer full of socks I do not like.
My wife found mail-order socks that she really likes - but they'll
only let her order 5 pairs at a time. She'd order a couple of dozen
if she could - and save the time, materials, and hassle of multiple
orders - but apparently some bean counter has decreed that this is
the Way It Should Be.
--
/~\ cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
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| Re: 1956 -- circuit reliability book [message #361624 is a reply to message #361567] |
Thu, 25 January 2018 15:54 |
Peter Flass
Messages: 8375
Registered: December 2011
Karma: 0
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Senior Member |
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Gene Wirchenko <genew@telus.net> wrote:
> On Wed, 24 Jan 2018 22:23:24 +0000, Ahem A Rivet's Shot
> <steveo@eircom.net> wrote:
>
>> On Wed, 24 Jan 2018 11:00:33 -0800
>> Gene Wirchenko <genew@telus.net> wrote:
>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> Intrigued!
>
> Sport Chek -- spelling is correct -- is a Canadian sporting goods
> store. Their Icebreaker line of socks has a lifetime guarantee. They
> are about $25 per pair. They are great, and I have yet to manage to
> wear out a pair though not through lack of trying. They are all I
> wear for socks now.
For the cost of sox I'm not sure this is a good bargain. I get six pairs
for, what, $8.00 (forget, haven't bought any in a year or so) If this is
the right price I'm paying 75¢/pr, so I'd have to hang around about 30 more
years to get my money's worth.
--
Pete
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| Re: 1956 -- circuit reliability book [message #361625 is a reply to message #361584] |
Thu, 25 January 2018 15:54 |
Peter Flass
Messages: 8375
Registered: December 2011
Karma: 0
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Senior Member |
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AndyW <Andy@nojunqmail.com> wrote:
> On 24/01/2018 18:04, Charlie Gibbs wrote:
>
>> This might be due to the consumer mindset, which eschews maintenance.
>> Buy a gadget, run it like hell until it breaks, throw it out. Lather,
>> rinse, repeat. Under such conditions I can see a bathtub curve as a
>> combination of infant mortality and wear out - both of which would be
>> eliminated by conscientious installation and maintenance.
>
> The modern mindset is to accept that the failure will occur despite
> preventive maintenance and instead work on making the failure
> convenient. You can prevent failure by throwing money at the problem
> (which is a diminishing returns situation) or you can detect an
> impending failure and just schedule a replacement at the next docking
> period, production line shutdown, holiday period etc.
Sounds like that IBM Watson ad where it schedules airplane maintenance.
>
> Most items, say a bearing, will degrade over time in a regular and
> predictable way* from tiny pitting in the bearing face,noise and
> deflection from the bearings hitting the 'potholes' that result in heat
> and vibration, through the complete collapse of the bearing. At various
> stages of the collapse the impending failure is detectable through
> various means such as vibration monitoring, temperature monitoring,
> acoustic monitoring etc. If you can detect it early enough then you can
> say with reasonable confidence how long it will be until failure.
>
> *note that an individual bearing will show a wear-out curve but the
> point at which the wear out starts is random hence the graphs for
> populations of bearings show a constant failure rate flat graph.
>
> sorry rambling on... 30 years at this and I get a bit geeky.
This sounds good for mechanical parts, but what about electronics? Things
seem to fail catastrophically with lots of magic smoke.
--
Pete
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| Re: 1956 -- circuit reliability book [message #361628 is a reply to message #361565] |
Thu, 25 January 2018 16:54 |
Andreas Kohlbach
Messages: 1456
Registered: December 2011
Karma: 0
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Senior Member |
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On Wed, 24 Jan 2018 23:21:56 +0000, Gareth's Downstairs Computer wrote:
>
> On 24/01/2018 22:23, Ahem A Rivet's Shot wrote:
>> On Wed, 24 Jan 2018 11:00:33 -0800
>> Gene Wirchenko <genew@telus.net> wrote:
>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> Intrigued!
>>
>
> I have a wristwatch with a lifetime guarantee, for when
> it malfunctions, the main spring jumps out and slashes
> your wrist
When I read some 80s magazines, for example about dot-matrix printers,
the ads say "Has all you'll ever need".
I mean back in 1986 to have a 24 needle printer must have been awesome
and you might have though, how could this can get any better.
Well you didn't know about laser- or ink printers back then, although
technology existed already. ;-)
--
Andreas
You know you are a redneck if
your wife has a beer belly and you find it attractive.
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| Re: 1956 -- circuit reliability book [message #361632 is a reply to message #361600] |
Thu, 25 January 2018 17:16 |
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Originally posted by: Bob Eager
On Thu, 25 Jan 2018 15:05:58 +0000, jmfbahciv wrote:
> Gene Wirchenko wrote:
>> On Wed, 24 Jan 2018 08:10:57 +0000, AndyW <Andy@nojunqmail.com> wrote:
>>
>> [snip]
>>
>>> For a population of similar items there is no real sudden rise in
>>> probability of failures with time, the point at which the failure
>>> starts is generally random which does go against the common belief.
>>
>> Actually, I found that I did have a sudden rise in failures on
>> socks. I would buy a lot of one type. For a long time, none would
>> wear out, then the odd one, then suddenly in a period of weeks, I would
>> have socks wearing out sometimes more than one in a week. About then,
>> I would buy new socks and toss the old ones.
>>
>> I have since switched to socks with a lifetime guarantee.
>
> LLBean's stuff lasts a long time. The t-shirts I bought in 1995 are now
> fraying at the edges. I just bought another batch which should last me
> a lifetime.
Don't know if you have Rohan in the USA, but I've worn little else on a
daily basis since 1984. OK, I have geeky T-shirts, often my design, but
apart from that...
(T-shirt example, in suitable (Greek-ish) font: ANCIENT GEEK
Rohan: http://www.rohan.co.uk
--
Using UNIX since v6 (1975)...
Use the BIG mirror service in the UK:
http://www.mirrorservice.org
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| Re: 1956 -- circuit reliability book [message #361633 is a reply to message #361383] |
Thu, 25 January 2018 17:18 |
mausg
Messages: 2483
Registered: May 2013
Karma: 0
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Senior Member |
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On 2018-01-25, Dave Garland <dave.garland@wizinfo.com> wrote:
> On 1/25/2018 9:05 AM, jmfbahciv wrote:
>> Gene Wirchenko wrote:
>>> On Wed, 24 Jan 2018 08:10:57 +0000, AndyW <Andy@nojunqmail.com> wrote:
>>>
>>> [snip]
>>>
>>>> For a population of similar items there is no real sudden rise in
>>>> probability of failures with time, the point at which the failure starts
>>>> is generally random which does go against the common belief.
>>>
>>> Actually, I found that I did have a sudden rise in failures on
>>> socks. I would buy a lot of one type. For a long time, none would
>>> wear out, then the odd one, then suddenly in a period of weeks, I
>>> would have socks wearing out sometimes more than one in a week. About
>>> then, I would buy new socks and toss the old ones.
>>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> LLBean's stuff lasts a long time. The t-shirts I bought in 1995
>> are now fraying at the edges. I just bought another batch which
>> should last me a lifetime.
>>
>> /BAH
>>
> And Bean's guarantees satisfaction for as long as you own the product.
> That's not precisely a lifetime guarantee, but it's close.
<fantasy>
"Sir, there is a customer out front that wants his money back, the
socks wore out."
"The usual, bring him out back so the socks can be examined, then use
the Magnum pistol"
</fantasy>
--
greymaus.ireland.ie
Just_Another_Grumpy_Old_Man
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| Re: 1956 -- circuit reliability book [message #361636 is a reply to message #361628] |
Thu, 25 January 2018 18:16 |
Jon Elson
Messages: 646
Registered: April 2013
Karma: 0
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Senior Member |
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Andreas Kohlbach wrote:
>
> When I read some 80s magazines, for example about dot-matrix printers,
> the ads say "Has all you'll ever need".
>
> I mean back in 1986 to have a 24 needle printer must have been awesome
> and you might have though, how could this can get any better.
In about 1982 or so, I had a 300 LPM Honeywell drum printer hooked to my
Z-80 CP/M system. That was quite a reverse engineering project to figure
out how to control it.
Jon
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| Re: 1956 -- circuit reliability book [message #361637 is a reply to message #361636] |
Thu, 25 January 2018 18:21 |
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Originally posted by: Gareth's Downstairs Computer
On 25/01/2018 23:16, Jon Elson wrote:
> Andreas Kohlbach wrote:
>
>
>>
>> When I read some 80s magazines, for example about dot-matrix printers,
>> the ads say "Has all you'll ever need".
>>
>> I mean back in 1986 to have a 24 needle printer must have been awesome
>> and you might have though, how could this can get any better.
> In about 1982 or so, I had a 300 LPM Honeywell drum printer hooked to my
> Z-80 CP/M system. That was quite a reverse engineering project to figure
> out how to control it.
>
> Jon
>
The joys of the ribbon belt stretching on the left side where it got the
most use!
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| Re: 1956 -- circuit reliability book [message #361643 is a reply to message #361628] |
Thu, 25 January 2018 20:24 |
Charlie Gibbs
Messages: 5313
Registered: January 2012
Karma: 0
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Senior Member |
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On 2018-01-25, Andreas Kohlbach <ank@spamfence.net> wrote:
> On Wed, 24 Jan 2018 23:21:56 +0000, Gareth's Downstairs Computer wrote:
>
>> On 24/01/2018 22:23, Ahem A Rivet's Shot wrote:
>>
>>> On Wed, 24 Jan 2018 11:00:33 -0800
>>> Gene Wirchenko <genew@telus.net> wrote:
>>>
>>>> I have since switched to socks with a lifetime guarantee.
>>>
>>> Intrigued!
>>
>> I have a wristwatch with a lifetime guarantee, for when
>> it malfunctions, the main spring jumps out and slashes
>> your wrist
>
> When I read some 80s magazines, for example about dot-matrix printers,
> the ads say "Has all you'll ever need".
>
> I mean back in 1986 to have a 24 needle printer must have been awesome
> and you might have though, how could this can get any better.
>
> Well you didn't know about laser- or ink printers back then, although
> technology existed already. ;-)
Oh, we knew about laser printers - but we didn't want to spend a quarter
of a million dollars on one, nor did we need to be able to print several
thousand pages at 167 pages per minute.
--
/~\ cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
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| Re: 1956 -- circuit reliability book [message #361666 is a reply to message #361614] |
Fri, 26 January 2018 03:35 |
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Originally posted by: AndyW
On 25/01/2018 18:31, Charlie Gibbs wrote:
> My wife found mail-order socks that she really likes - but they'll
> only let her order 5 pairs at a time. She'd order a couple of dozen
> if she could - and save the time, materials, and hassle of multiple
> orders - but apparently some bean counter has decreed that this is
> the Way It Should Be.
I love bean counters, they don't understand the real world at all.
In my place of work the bean counters think that if it takes an hour to
paint the inside of a phone booth then if we get 60 people to do the job
it will only take a minute.
Andy
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| Re: 1956 -- circuit reliability book [message #361667 is a reply to message #361625] |
Fri, 26 January 2018 03:52 |
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Originally posted by: AndyW
On 25/01/2018 20:54, Peter Flass wrote:
> This sounds good for mechanical parts, but what about electronics? Things
> seem to fail catastrophically with lots of magic smoke.
Modern electronics (with the exception of capacitor drift) usually just
fail without appreciable degradation which is where redundant systems
come into play with supervisor systems to handle the votes. For critical
systems it is common to have multiple parallel systems all voting with a
supervisor system making the decision based on the votes. The failure of
one system can be detected and worked around. For really critical
systems the parallel systems are often built using different design
teams and technology to eliminate common mode failures.
Less critical systems have a supervisor to detect a failure and switch
to a 'graceful degradation' mode that provides basic level service like
your car switching to 'limp home' mode.
At one time we spent millions of toughening up electronics,
pre-stressing and hardening etc but they still failed. The modern idea
for repairable systems (eg not one-shot items such as space probes) is
to accept that they will fail and design the system to handle those
failures. Even desktop PCs can be built to handle failure with the use
of RAID arrays that saves you data even after a catastrophic failure.
I always had the thought to add a filter to server room AirCon then we
might be able to catch the magic smoke and glue it back into the escape
point. Maybe this is my million dollar idea.......
Andy
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| Re: 1956 -- circuit reliability book [message #361668 is a reply to message #361628] |
Fri, 26 January 2018 04:02 |
|
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Originally posted by: AndyW
On 25/01/2018 21:54, Andreas Kohlbach wrote:
> When I read some 80s magazines, for example about dot-matrix printers,
> the ads say "Has all you'll ever need".
>
> I mean back in 1986 to have a 24 needle printer must have been awesome
> and you might have though, how could this can get any better.
>
> Well you didn't know about laser- or ink printers back then, although
> technology existed already. ;-)
Nothing quite like the sound of a DM printer. Crackle of a log fire,
roar of a waterfall, zizz of a DM printer and the hiss of a paraffin
pressure lamp. Favourite sounds.
I had a DM printer in regular use until about 10 years ago. I was
contacted by a local church in the early 90s who wondered if they should
get a desktop publishing system with laser printers for the notices and
orders of service. Until then they has a typewriter and a Gestetner
duplicator (I think Mimeograph if you are left side of the pond).
I got hold of a Mac SE and a dot matrix printer being dumped by my work
and, without a ribbon, the DM printer cut the stencil perfectly giving
access to 'hi res' graphics.
It was a cracking little set up and was only retired when the duplicator
ink became hard to obtain.
Now they have a PC and laser printer. Perfect prints but souless and no
character.
Andy
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| Re: 1956 -- circuit reliability book [message #361669 is a reply to message #361666] |
Fri, 26 January 2018 04:06 |
mausg
Messages: 2483
Registered: May 2013
Karma: 0
|
Senior Member |
|
|
On 2018-01-26, AndyW <Andy@nojunqmail.com> wrote:
> On 25/01/2018 18:31, Charlie Gibbs wrote:
>> My wife found mail-order socks that she really likes - but they'll
>> only let her order 5 pairs at a time. She'd order a couple of dozen
>> if she could - and save the time, materials, and hassle of multiple
>> orders - but apparently some bean counter has decreed that this is
>> the Way It Should Be.
>
> I love bean counters, they don't understand the real world at all.
> In my place of work the bean counters think that if it takes an hour to
> paint the inside of a phone booth then if we get 60 people to do the job
> it will only take a minute.
>
> Andy
>
Also the old story about
"If a woman can produce a child in nine months,
X number of women can do it in a day."
Sadly , from whatI hear from obs and gynie, the latter may be true in
time.
--
greymaus.ireland.ie
Just_Another_Grumpy_Old_Man
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| Re: 1956 -- circuit reliability book [message #361675 is a reply to message #361383] |
Fri, 26 January 2018 09:11 |
jmfbahciv
Messages: 6173
Registered: March 2012
Karma: 0
|
Senior Member |
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Dave Garland wrote:
> On 1/25/2018 9:05 AM, jmfbahciv wrote:
>> Gene Wirchenko wrote:
>>> On Wed, 24 Jan 2018 08:10:57 +0000, AndyW <Andy@nojunqmail.com> wrote:
>>>
>>> [snip]
>>>
>>>> For a population of similar items there is no real sudden rise in
>>>> probability of failures with time, the point at which the failure starts
>>>> is generally random which does go against the common belief.
>>>
>>> Actually, I found that I did have a sudden rise in failures on
>>> socks. I would buy a lot of one type. For a long time, none would
>>> wear out, then the odd one, then suddenly in a period of weeks, I
>>> would have socks wearing out sometimes more than one in a week. About
>>> then, I would buy new socks and toss the old ones.
>>>
>>> I have since switched to socks with a lifetime guarantee.
>>
>> LLBean's stuff lasts a long time. The t-shirts I bought in 1995
>> are now fraying at the edges. I just bought another batch which
>> should last me a lifetime.
>>
>> /BAH
>>
> And Bean's guarantees satisfaction for as long as you own the product.
> That's not precisely a lifetime guarantee, but it's close.
They do. I had a pair of gloves that had some of the fingers fraying.
They offered to fix them. I refused saying it wasn't worth the expense
and buying a new pair was best for both of us.
/BAH
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| Re: 1956 -- circuit reliability book [message #361677 is a reply to message #361669] |
Fri, 26 January 2018 10:40 |
Charles Richmond
Messages: 2754
Registered: December 2011
Karma: 0
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Senior Member |
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On 1/26/2018 3:06 AM, mausg@mail.com wrote:
> On 2018-01-26, AndyW <Andy@nojunqmail.com> wrote:
>> On 25/01/2018 18:31, Charlie Gibbs wrote:
>>> My wife found mail-order socks that she really likes - but they'll
>>> only let her order 5 pairs at a time. She'd order a couple of dozen
>>> if she could - and save the time, materials, and hassle of multiple
>>> orders - but apparently some bean counter has decreed that this is
>>> the Way It Should Be.
>>
>> I love bean counters, they don't understand the real world at all.
>> In my place of work the bean counters think that if it takes an hour to
>> paint the inside of a phone booth then if we get 60 people to do the job
>> it will only take a minute.
>>
>> Andy
>>
>
> Also the old story about
> "If a woman can produce a child in nine months,
> X number of women can do it in a day."
>
> Sadly , from whatI hear from obs and gynie, the latter may be true in
> time.
>
The population bloat occurs because a woman has a baby every 8 seconds.
What we have to do... is get to that woman and STOP her!!! ;-)
--
numerist at aquaporin4 dot com
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| Re: 1956 -- circuit reliability book [message #361681 is a reply to message #361668] |
Fri, 26 January 2018 12:37 |
Charlie Gibbs
Messages: 5313
Registered: January 2012
Karma: 0
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Senior Member |
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On 2018-01-26, AndyW <Andy@nojunqmail.com> wrote:
> Nothing quite like the sound of a DM printer. Crackle of a log fire,
> roar of a waterfall, zizz of a DM printer and the hiss of a paraffin
> pressure lamp. Favourite sounds.
Yes, it was quite distinctive. Too bad the guys who produced the
original Tron movie didn't realize this; near the end there's a
close-up view of a daisy-wheel printer showing some messages,
while the dubbed-in sound is that of a dot-matrix printer.
--
/~\ cgibbs@kltpzyxm.invalid (Charlie Gibbs)
\ / I'm really at ac.dekanfrus if you read it the right way.
X Top-posted messages will probably be ignored. See RFC1855.
/ \ HTML will DEFINITELY be ignored. Join the ASCII ribbon campaign!
|
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| Re: 1956 -- circuit reliability book [message #361682 is a reply to message #361681] |
Fri, 26 January 2018 13:32 |
|
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Originally posted by: Gareth's Downstairs Computer
On 26/01/2018 17:37, Charlie Gibbs wrote:
> On 2018-01-26, AndyW <Andy@nojunqmail.com> wrote:
>
>> Nothing quite like the sound of a DM printer. Crackle of a log fire,
>> roar of a waterfall, zizz of a DM printer and the hiss of a paraffin
>> pressure lamp. Favourite sounds.
>
> Yes, it was quite distinctive. Too bad the guys who produced the
> original Tron movie didn't realize this; near the end there's a
> close-up view of a daisy-wheel printer showing some messages,
> while the dubbed-in sound is that of a dot-matrix printer.
>
How quiet we thought the DecWriter to be after the
clanking Teletypes!
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| Re: 1956 -- circuit reliability book [message #361690 is a reply to message #361584] |
Fri, 26 January 2018 15:51 |
hancock4
Messages: 6746
Registered: December 2011
Karma: 0
|
Senior Member |
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On Thursday, January 25, 2018 at 2:31:32 AM UTC-5, AndyW wrote:
>> This might be due to the consumer mindset, which eschews maintenance.
>> Buy a gadget, run it like hell until it breaks, throw it out. Lather,
>> rinse, repeat. Under such conditions I can see a bathtub curve as a
>> combination of infant mortality and wear out - both of which would be
>> eliminated by conscientious installation and maintenance.
>
> The modern mindset is to accept that the failure will occur despite
> preventive maintenance and instead work on making the failure
> convenient. You can prevent failure by throwing money at the problem
> (which is a diminishing returns situation) or you can detect an
> impending failure and just schedule a replacement at the next docking
> period, production line shutdown, holiday period etc.
When the Bell System brought out electronic switching, the devices
had dual processors for reliability. How often the active device
failed and they had to switch to backup I don't know. One book
suggests that while overall ESS was more reliable than relays,
if ESS failed, it all failed, as opposed to merely slowing down.
The book also said if an ESS got overloaded it would fail, while
relays would slow down (giving a warning first). ("Telephone" by
John Brooks).
In Jan 61, Bell tried out a new telephone set in a trial. They
found that, as they put it, "the mylar foil capacitor and diodes
did not 'perform as expected' and needed to be redesigned".
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| Re: 1956 -- circuit reliability book [message #361691 is a reply to message #361625] |
Fri, 26 January 2018 15:54 |
hancock4
Messages: 6746
Registered: December 2011
Karma: 0
|
Senior Member |
|
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On Thursday, January 25, 2018 at 3:54:14 PM UTC-5, Peter Flass wrote:
>> The modern mindset is to accept that the failure will occur despite
>> preventive maintenance and instead work on making the failure
>> convenient. You can prevent failure by throwing money at the problem
>> (which is a diminishing returns situation) or you can detect an
>> impending failure and just schedule a replacement at the next docking
>> period, production line shutdown, holiday period etc.
>
> Sounds like that IBM Watson ad where it schedules airplane maintenance.
Was this in the late 1940s with tab machines? IBM did a lot of
advertising back then.
In the 1960s, an engineering firm developed railroad maintenance
software. By tracking failures of every component, they were
able to identify problem components, more so than practical before.
On a big railroad, it ran on a 360-65. On a small line, it ran on
an 1130.
>
>>
>> Most items, say a bearing, will degrade over time in a regular and
>> predictable way* from tiny pitting in the bearing face,noise and
>> deflection from the bearings hitting the 'potholes' that result in heat
>> and vibration, through the complete collapse of the bearing. At various
>> stages of the collapse the impending failure is detectable through
>> various means such as vibration monitoring, temperature monitoring,
>> acoustic monitoring etc. If you can detect it early enough then you can
>> say with reasonable confidence how long it will be until failure.
>>
>> *note that an individual bearing will show a wear-out curve but the
>> point at which the wear out starts is random hence the graphs for
>> populations of bearings show a constant failure rate flat graph.
>>
>> sorry rambling on... 30 years at this and I get a bit geeky.
>
> This sounds good for mechanical parts, but what about electronics? Things
> seem to fail catastrophically with lots of magic smoke.
>
> --
> Pete
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