Today's Message Index:
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1. 08:31 AM - Re: Re: star washers (Rick Beebe)
2. 01:40 PM - Transistor Dimmers (Paul Millner)
3. 08:41 PM - Re: Transistor Dimmers (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: star washers |
I love Nord Lock washers even though they're expensive. I used them on
all the battery connections in the truck I converted to electric. I
check them every 6 months and have never found one coming loose.
--Rick
On 12/14/2018 10:27 PM, user9253 wrote:
> I am not familiar with Rotax split washers. Where are they used on the
> Rotax?
> The prop bolts on my Rotax have wedge-lock washers, no safety wire required.
Matco breaks also use wedge-lock washers.
> When wedge-lock (Nord Lock) washers are used, it is actually harder to loosen
a fastener than to tighten it.
>
> --------
> Joe Gores
>
Message 2
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Subject: | Transistor Dimmers |
Robert L. Nuckolls, III wrote:
> Somewhere in my archives, I have a letter from
> the head-shed of single engine electrical systems
> rejecting my proposal for replacing the too-warm,
> panel dimming rheostats with a remotely mounted
> array of power transistors on heat sinks. This
> would have been about 1964 or thereabouts.
>
> He offered a litany of down-sides . . .
>
> A about 5 years later, the same idea cropped up
> across town on the light twins . . . a short
> time later, solid state dimming migrated into the
> single engine airplanes. We COULD have beat
> the twin engine line to this enhancement by
> several years. Oh well . . .
There was that AD on 172s with those rheostats in the overhead panel...
as the panel aged, heated, and deformed, the rheostat contacts would
contact ground, and start a nice little fire fueled by the plastic panel
and surrounding materials...
Of course, those of us blessed with the transistor dimmers got good at
replacing the 2N3203 power transistors (and later the RCA equivalent
replacements), 'cause there was no current limiting, and even a
momentary short, easy to do when wiggling a plastic overlay panel, would
blow the transistor. A one ohm resistor in series with the load would
nicely current limit so that the transistor wouldn't blow... not
elegant, but it worked! :-)
Paul
Message 3
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Subject: | Re: Transistor Dimmers |
>
>There was that AD on 172s with those rheostats in the overhead
>panel... as the panel aged, heated, and deformed, the rheostat
>contacts would contact ground, and start a nice little fire fueled
>by the plastic panel and surrounding materials...
>
>Of course, those of us blessed with the transistor dimmers got good
>at replacing the 2N3203 power transistors (and later the RCA
>equivalent replacements), 'cause there was no current limiting, and
>even a momentary short, easy to do when wiggling a plastic overlay
>panel, would blow the transistor. A one ohm resistor in series with
>the load would nicely current limit so that the transistor wouldn't
>blow... not elegant, but it worked! :-)
Oh yeah . . . forgot about that. Same problem
at Beech. Seems that the assembly line would
go through a couple of dimmer assemblies before
they cleaned all the shorts out of the post-lites
installations. Got to revisit the dimmer issues
for Beech while I was at ElectroMech. I designed
a 4-channel incandescent/1-channel E.L. supply with
all four outputs short circuit tolerant. I think
they still build that for the Bonanzas and Barons.
Electromech Electronics Circuit Board
I found it interesting that all three of the featured
products on ElectroMech's electronic products promo
http://www.electromech.com/images/data-sheets/Electronics.pdf
are devices I designed for Beech back in the 80's . . .
Gee, I would think they had some something newer
since I worked there!
Bob . . .
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