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Date: Fri, 11 May 2007 17:19:56 -0700 (PDT)
From: Perry Mick <pjmick@verizon.net>
Subject: Re: [FlyRotary] Re: EC2 question
To: flyrotary@lancaironline.net
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If you use them, derate well. For a 14V power source use at least 25V parts, 50V would be better. The dielectric contains oxygen that feeds the fire once it gets started. I work in the avionics business and we aren't allowed to use them in new designs.
   
   
   
  Geeze, Jim.  Here I've been using tantalum capacitors in my circuit boards.  Are these failure modes spontaneous or are they triggered by something like over voltage, over temp, etc.  I guess I'm a bit surprised at the violence of their demise - I would think something like that would have curtailed their use in electronic circuits.
   
  Ed
    ----- Original Message ----- 
  From: James Maher 
  To: Rotary motors in aircraft 
  Sent: Friday, May 11, 2007 5:50 PM
  Subject: [FlyRotary] Re: EC2 question
  

  Al,
  I would be very careful about adding any tantalum capacitors.
  Back when I worked as an electronic technician I discovered the failure mode of these devices.
  They start off with a little leakage current.
  As they leak the get hotter.
  The hotter they get the more they leak.
  This continues until they build to critical temp and then explode
  sending a molten projectile 10 feet or more.
  I actually had some blowup while testing and they burnt a hole in the floor
  10-20 feet away.
After that I always made sure that there was a metal cover over the unit being tested.
  Just a word to the wise.
  Jim
  
Al Gietzen <ALVentures@cox.net> wrote:
    SNIP
   
  
47uf, 16V tantalum were added to each processor

Pin 8 of connector is now grounded.
Pin 28 of connector is now grounded.

Al


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<div>If you&nbsp;use them,&nbsp;derate well. For a 14V power source use at least 25V parts, 50V would be better. The dielectric contains oxygen that feeds the fire once it gets started. I work in the avionics business and we aren't allowed to use them in new designs.</div>  <div>&nbsp;</div>  <div>&nbsp;</div>  <div>&nbsp;</div>  <DIV><FONT face=Arial>Geeze, Jim.&nbsp; Here I've been using tantalum capacitors in my circuit boards.&nbsp; Are these failure modes spontaneous or are they triggered by something like over voltage, over temp, etc.&nbsp; I guess I'm a bit surprised at the violence of their demise - I would think something like that would have curtailed their use in electronic circuits.</FONT></DIV>  <DIV><FONT face=Arial></FONT>&nbsp;</DIV>  <DIV><FONT face=Arial>Ed</FONT></DIV>  <BLOCKQUOTE>  <DIV>----- Original Message ----- </DIV>  <DIV><B>From:</B> <A title=deltaflyer@prodigy.net href="mailto:deltaflyer@prodigy.net" target=_blank>James Maher</A> </DIV> 
 <DIV><B>To:</B> <A title=flyrotary@lancaironline.net href="mailto:flyrotary@lancaironline.net" target=_blank>Rotary motors in aircraft</A> </DIV>  <DIV><B>Sent:</B> Friday, May 11, 2007 5:50 PM</DIV>  <DIV><B>Subject:</B> [FlyRotary] Re: EC2 question</DIV>  <DIV><BR></DIV>  <DIV>Al,</DIV>  <DIV>I would be very careful about adding any tantalum capacitors.</DIV>  <DIV>Back when I worked as an electronic technician I discovered the failure mode of these devices.</DIV>  <DIV>They start off with a little leakage current.</DIV>  <DIV>As they leak the get hotter.</DIV>  <DIV>The hotter they get the more they leak.</DIV>  <DIV>This continues until they build to critical temp and then explode</DIV>  <DIV>sending a molten projectile 10 feet or more.</DIV>  <DIV>I actually had some blowup while&nbsp;testing and they burnt a hole in the floor</DIV>  <DIV>10-20 feet away.<BR>After that I always made sure that there was a metal cover over the unit being tested.</DIV>  <DIV>Just a word
 to the wise.</DIV>  <DIV>Jim</DIV>  <DIV><BR><B><I>Al Gietzen &lt;ALVentures@cox.net&gt;</I></B> wrote:</DIV>  <BLOCKQUOTE class=replbq>  <DIV>SNIP</DIV>  <DIV>&nbsp;</DIV>  <DIV><BR>47uf, 16V tantalum were added to each processor<BR><BR>Pin 8 of connector is now grounded.<BR>Pin 28 of connector is now grounded.<BR><BR>Al<BR></DIV></BLOCKQUOTE></BLOCKQUOTE>
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