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From: "Al Gietzen" <ALVentures@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Tantlum capacitors
Date: Sat, 12 May 2007 22:22:22 -0800
Message-ID: <000001c79527$1155fe60$6400a8c0@BigAl>
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Here's the opinion of my "expert" who has been designing and breadboarding
custom microprocessors and electronics stuff for 15 years  -- Oh, BTW, the
Ta capacitors on my board are rated for 16V and are on a 5V circuit.

Al

Subject: Re: FW: [FlyRotary] Re: EC2 question

A few things to know about tantalum capacitors:
Just about all electronic devices manufactured in the last 25 years 
use tantalum capacitors.  If the explosion problem was an issue, then 
cell phones, laptops, auto engine controllers, medical life support 
equipment, satellites, televisions, nuclear power plants would all be 
having problems.  And believe me, when it comes to consumer 
electronics, there is no voltage de-rating because a higher voltage 
capacitor costs more.

Although the more I think about it, the idea of exploding cell phones 
is appealing, especially when people are talking while driving.:-)

The claim about not using tantalum capacitors in aircraft is 
dubious.  If this were the case, then nobody would be able to bring 
their electronics on-board a commercial aircraft.  I would find it 
amazing if your EFIS/GPS doesn't have tantalum capacitors in it.

I'm quite certain that Tracy already has tantalum caps on the ECU 
board.  The primary failure mode of this type of capacitor is a short 
circuit.  Since it's unlikely to have two fail at once, the short 
would be isolated to one controller and you would fly on the other.

In all of the circuits I've designed, I have never had a board come 
back from the field with a failed tantalum capacitor.  All of the 
failures I've seen (2) occurred in the first few seconds of testing 
(1) or because the electronic assembler installed the capacitor 
backwards (reverse polarity) (1).