On 02/02/2017 09:36 PM, Jeff Liebermann wrote:
On Thu, 02 Feb 2017 16:44:53 -0600, wrote:

I'm 66 years old. According to my doctor, I dont have any bad
capacitors, (just arthritis).

I'm 69 years old. My body mechanic says I have pump and inside
plumbing problems. Perhaps I should replace him with a plumber?

Seriously, I wonder what the life expectancy is for the new caps
(meaning the replacements for the wax coated paper caps. ???)

There are online lifetime calculators for electrolytic and other types
of capacitors. For example:
http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
http://www.chemi-con.com/education (click on Capacitor Life)
The major culprit is internal heating from high ripple current
resulting the electrolyte leaking or evaporating. Temperature also
has a big effect. There are graphs on the capacitor data sheets that
approximate the lifetime characteristics.

And what are these newer ones made from?

For electrolytics, try polymer caps:
https://en.wikipedia.org/wiki/Polymer_capacitor#Lifetime.2C_service_life
http://www.mouser.com/pdfdocs/Panasonic_Capacitors_WP_final.PDF

I know the mica and ceramic caps are reliable and last almost forever.

Not all ceramics are that reliable. MLCC (multi-layer ceramic caps)
are rather fragile and microphonic.

A for electrolytic caps, it seems that the newer ones have a much
shorter life than the old ones did.

Nope. The old ones filtered at 120 Hz. The new caps filter at 100 to
300 KHz. Internal dissipation follows frequency.

That's
why those old radios still work after 60 or 80 years, while most stuff
made today is in a landfill in less than 10 years.

Todays products are intentionally designed to be difficult to repair
and to only last as long as the warranty period. With the proper
design tools and models, it is possible to predict the life of an
electronic (or mechanical) product. Anything that lasts longer than
the warranty period is deemed to be "over-designed". It is then
redesigned using lower rating or cost components so that everything
blows up at the same time. I've seen it happen.


Oliver Wendell Holmes wrote a very funny poem about that, "The Deacon's
Masterpiece, Or, The Wonderful One-Hoss Shay".

Here it is, read by Eddie Albert.

https://www.youtube.com/watch?v=wiOHhhwnK6k

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net