flyrotary@lancaironline.net Mailing List Archive

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.

----- 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