Re: Detectig fan failure - modes of failude

From: Jim Thompson (thegreatone_at_example.com)
Date: 09/15/04 

Date: Wed, 15 Sep 2004 08:02:02 -0700

On Wed, 15 Sep 2004 13:02:49 GMT, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Wed, 15 Sep 2004 15:00:02 +0200, the renowned "SioL"
><Sio_spam_L@same.net> wrote:
>
>>I'm designing a device with two convenient solder pads on the PCB
>>providing LC filtered power to the fan to. This will be a smallish 1W
>>12V fan, with only two connections (those are cheaper and I can't get
>>the 3-pin version of 40x40x20 easily).
>>
>>It occurred to me that it might be great to have failure detection. Now
>>it'd be easy if these were the 3-pin fans, but they're not. I wonder whether
>>someone has some experience on modes of failure. Does it consistently
>>draw more current, no current or should I watch for some AC ripple on
>>supply line during normal operation, I'd expect there would be some and
>>it'd stop if the fan stopped rotating.
>
>Yes, that will work. It might be patented however.
>
>>I'll possibly settle for a NTC if everything else fails, but I have some
>>PCB real-estate left for other solutions.
>>
>>SioL
>
>
>
>Best regards,
>Spehro Pefhany

They have horrible current ripple, so bad that I once designed a
quick-fix circuit to fill-in the ripple, because the ripple was
disturbing a nearby CRT in a piece of OmniComp/GenRad portable gear.

Did someone actually patent looking at the ripple ?:-)

                                        ...Jim Thompson 

-- 
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

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