$429 Dimmer Switch

Jay Honeck wrote:
Personally, I think the dimmer circuitry in the Cherokee is perhaps the
dumbest thing I've seen in aviation. Even I, as a total neophyte, can see
that the system is hopelessly obtuse.

Ray has explained to you, twice in this thread, why transistors are used.
If you can't understand the technology, stop commenting on it.

--- Jay


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Roy Smith wrote:

Ray Andraka wrote:

When my dimmer does go, or I add more lighting to the panel, I'll
probably opt for one of the pulse width modulated ones (those are
much more complicated than the piper pass transistor, but they also
dissipate very little power).

The next step in the evolution is to get rid of all those incandescant
bulbs and replace them with LEDs. Lower power consumption for the same
light output, and they never burn out.

Yep.., I've made my own GE330 replacements for the annuniciator and
gear-down lights using white LEDs.
I believe there are commercially avialable units but be carefull
because incandescent lamps are non-polarised but the polarity of the
lamp sockets is random. (My Arrow requires a + base for the gear lamps
but a - base for the annunciators)

-And any engineer that designs a dimming circuit without short circuit
protection
of the output device should be staked out with ants and honey.

Yes, I agree, however it wasn't designed with output protection and anybody
that works on it shoud understand that

- I have my sources that I've
published with a Chief Counsel's opinion.

A chief counsel doesn't survail those of us out in the field.


As
-the chief inspector for a large repair station, if I see an aircraft for an
-annual with some kind of aftermarket or home made dimmer system....it better
-have a 337 associated with it....not because I'm a jerk or an a**hole, but
-because that is what the regulations require.
-And again, I beg to differ with your interpretation, as does the Chief
Counsel.

I beg to differ with you and your chief counsel's opinion, if its not as it
came from the factory then it does not conform to its type design and needs a
vehicle of approval, what-ever that may be. I'll be glad to argue that point
to you or counsel (as long as we can avoid the flaming)


- Them's the breaks, ain't they?

Yup, its a heck of a biz....gotta love it or it'll kill ya....figuratively


- Ask your FAA inspector for the
approved definition of safety. There is none. How can any agency guide toward
that which it can't even define?"

Jim, of all the stuff of your's I've read, I must say that is a great line.....
Lets not however, miss the forest for the trees. Some legal eagle in a nice
air conditioned office hasn't a clue about what really happens out here on the
front lines of the maintenance battlefield. Those of us with grease under our
finger nails don't deal with a Chief Counsel, we deal with Aviation Safety
Inspectors that may or may not know as much as we do. Truth be told, I really
enjoy "playing ball" with the FAA, but, ya know.....if I make 'em mad enough,
they'll take the ball and bat and go home....if you know what I mean.

By the way, I'd enjoy arguing regulations with you....as chief inspector for a
repair station, that's what I do for a living. Unfortunately, my responses may
be a little delayed if it involves quoting regs. I surf news groups from home
and all my reg stuff is at work.

I've proven the Feds wrong a few times, but eaten a lot of crow along the way!


By the way Jim, didn't I read in one of your posts that you were a Ham?? Be
glad to try a sked on HF and we can really get into a spirited discussion.....I
can work 160 up to 10 with 100 watts to a dipole oriented east to west.

best 73 John

Ray has explained to you, twice in this thread, why transistors are used.
If you can't understand the technology, stop commenting on it.

Wow, we normally can't find anyone here to defend the high-tech 1974 Chevy
Nova technology found in my Piper -- thanks!

Your view is, um, refreshing, somehow. Kinda like the Amish, I suppose, but
I guess I could get used to it.

Actually, flying a 30 year old airplane, I have little choice. :-(
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

: Personally, I think the dimmer circuitry in the Cherokee is perhaps the
: dumbest thing I've seen in aviation. Even I, as a total neophyte, can see
: that the system is hopelessly obtuse.

: Strangely, older Cherokees had a much simpler dimmer circuit. I wonder why
: Piper made it so complex later on, and I wonder if they've corrected this
: mess in their new planes?

I won't debate the older vs. newer circuit too much, except to say that it
moves the heat loss from a rheostat to a transistor. Both are linear "regulators",
but due to the changing load requirements a resistor makes a very poor choice. My
plane's the older variety, and the lights are off for about 75% of the travel of the
dimmer. The other 25% goes from off to full bright, and makes the last 25% of the
rheostat coils have to dissipate all the power.

They're both a bit clunky (PWM being more efficient, but prone to noise as
previously mentioned). Aside from this being an AIRPLANE, the transistor setup is
CHEAPER and "better" from the linearity and robustness standpoint (TO-3 package 2N3055
is a tough transistor that can dissipate a lot of power). In reality, the 20W or so
max is negligible power lost (1-2A draw) and a decent compromise for complexity
and noise immunity. Still better are LEDs... less power, and even a linear regulator
won't have to dissipate much.

Hope that helps describe why they went to it.

-Cory



--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

Hope that helps describe why they went to it.

Thanks, Cory!

Do you know if there's a legal way to put LEDs in my plane?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message news:rkp4c.18266$mM.131800@attbi_s02...
And it's not even for the Dept. of Defense! :-)

For those of you thinking about airplane ownership (and I know you're
lurking out there!), we just got the bill to replace one of the two dimmer
switches (and a few light bulbs) in our Pathfinder's panel.

$104 in parts, 5 hours labor (It's a real bitch to diagnose and get at in a
Cherokee...).

Total: $429.73.

Gotta love aviation.

That is why alot of us are building experimental planes. I have owned
several certified ships and "Never" again will I get
screwed......Happy Flying.

Ben Haas N801BH

On Sat, 13 Mar 2004 08:10:48 -0800, Jim Weir wrote:


Had a double helping of bitch flakes this morning, did we Stu?

Jim

Man, I just couldn't resist!



Stu Gotts
shared these priceless pearls of wisdom:

-Oh no! Someone having the audacity to disagree with King Weir!
-That'll make him spit out his morning latte! Stand by for the flames.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

On 13 Mar 2004 22:26:18 GMT, ospam (JohnN3TWN)
wrote:

snip

By the way, I'd enjoy arguing regulations with you....as chief inspector for a
repair station, that's what I do for a living. Unfortunately, my responses may
be a little delayed if it involves quoting regs. I surf news groups from home
and all my reg stuff is at work.

http://www.access.gpo.gov/nara/cfr/w...4cfrv1_04.html

enjoy

TC

And please to add:

http://www.awp.faa.gov/new/fsdo/ans_jan2_98.htm

http://www.awp.faa.gov/new/fsdo/ans_july1_97.htm

http://www.awp.faa.gov/new/fsdo/ans_apr3_99.htm

Jim


shared these priceless pearls of wisdom:

-On 13 Mar 2004 22:26:18 GMT, ospam (JohnN3TWN)
-wrote:
-
-snip
-
-By the way, I'd enjoy arguing regulations with you....as chief inspector for
a
-repair station, that's what I do for a living. Unfortunately, my responses
may
-be a little delayed if it involves quoting regs. I surf news groups from
home
-and all my reg stuff is at work.
-
-http://www.access.gpo.gov/nara/cfr/w...4cfrv1_04.html
-
-enjoy
-
-TC



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com