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Date: Wed, 04 Feb 2009 19:03:52 -0500
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From: "Richard T. Schaefer" <schaefer@rts-services.com>
Subject: RE: [LML] Electrical System Voltage Waveforms
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Cool ... The excursions can still be a problem for avionics that do not
comply with strict aviation standards. (Which include size and length of
voltage excursions during normal operations)

i.e. during the voltage sag, or low voltage, you can start driving some
transistor switches in the power supplies into a linear mode ... they then
have to dissipate considerably more power, and if they are not heat sinked
can burn up.

i.e. during some of the over voltage events, caused by shutting off high
current devices where the regulator has to adjust, you can get close to 
maximum junction voltages on some transistors. The best protection here is
good condition LARGER batteries. 


NOTE: Internal resistance of a battery which increases with age and
inversely with size (typically) of the battery will cause larger swings on
both of these events.
 
r.t.s.  

-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Isaac
Heizer
Sent: Tuesday, February 03, 2009 2:57 PM
To: lml@lancaironline.net
Subject: [LML] Electrical System Voltage Waveforms

Some posts about failing avionics got my attention a couple of weeks back,
and I resumed worrying about noise or other evil doings on the electrical
bus of my newly completed ES-P.  So I cobbled together some equipment to
investigate.  Bottom line is I didn't find anything unexpected....some
details are in the attached PDF file.

-isaac
ES-P N7842K