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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-745348@logan.com>
Subject: Re: [FlyRotary] Re: Digital Fuel Monitoring System
Date: Fri, 18 Feb 2005 23:34:43 -0500
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Ok, folks I got the message on showing resistor "legs" - too risqué for some
folks I guess {:>).

Seriously, I think I will redesign the board to use Surface mount resistors
and capacitors and that will eliminate legs - of course it was sure nice to
use those legs to leap over traces.

Thanks for the input, Finn, Todd, Charlie, et al

Ed


----- Original Message -----
From: "Charlie England" <ceengland@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, February 18, 2005 10:46 PM
Subject: [FlyRotary] Re: Digital Fuel Monitoring System


> Hey Ed, want a 2nd opinion? What Finn said.
>
> Same reason that 13B through-bolts break.
>
> Charlie
>
>
> Finn Lassen wrote:
>
> > Hi Ed.
> >
> > This of course all only applies to electronics in a vibration exposed
> > environment.
> > Good practice, as I was taught it many years ago, is to have hole
> > spacings to allow components to lie flat on the board.
> > Of course there are exceptions like power resistors that need airflow
> > around them, but they should be mounted with "stand-offs" (small tubes
> > on their legs). The rule used to be that components should not be held
> > in place by the solder, but by their mechanical mounting. That's why
> > the pins are typically bent 45 degrees where they stick through the
> > PCB before being cut off and soldered. Heavy components are
> > additionally secured with some kind of mechanical fastener or globs of
> > goo (technical term). Now obviously the weight of the body of the
> > component in relationship to number of pins/legs is a factor. An
> > example would be an IC with oodles (another technical term) of pins.
> >
> > I "grew up" in a company that secialized in sound and vibration. It
> > was very educational to watch a PCB board mounted on a "shaker"
> > (basically a loudspeaker where there membrame was replaced with a
> > mounting place) lit with a strobe light synchronized to the frequency
> > sweep. Components dancing around and finally falling off if not
> > properly supported (mounted).
> >
> > But that was then. Now we have surface mounted components which I know
> > nothing about...
> >
> >
> > Finn (Looks like I've been kicked off the list again)
> >
> >
> > Geez, Finn, I was unaware that there was a "protocol" for resistor
> > sizes on PC boards.  Seriously, is there some reason (vibration?) for
> > forcing resistors all the way to the board or is it just "esthetics?".
> >
> > Ed A
>
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>