Jim Weir: help to add car radio to aviation audio panel music input

[Brian DeFord]

Jim,

I've read your columns regarding aircraft electronics for years and I
just can't seem to get an answer for a problem I have. I'm trying to
connect a Alpine AM/FM/CD player in my plane to the music input of my
audio panel (a GMA340) The problem is that I can't hear the music
because the volume is so low. I believe it has something to do with
the input and output level of the two devices, but not being an
electronics guru I don't know how I can make them work together. Do you
have any suggestions? The output of the radio (pre-amplified) is 4V /
10K ohms max voltage and the audio panel music input is 510 ohm
impedance and <500 mV RMS for full output typical, 1V AC RMS MAX (3V
peak to peak).

I'd be happy to supply more info is required. This is probably a
simple question, but I'm stumped!

Regards,
Brian DeFord

[RST Engineering]

It is a relatively simple problem involving nothing more complex than a high
impedance output (intended to drive 10k) and a low impedance input (510 ohm)
intended for line level inputs. If that output impedance is really meant to
deliver 4 volts (probably peak to peak, although you didn't state) into 10k,
then the voltage into a 510 ohm resistor will be something on the order of a
quarter of a volt peak to peak, or 72 millivolts RMS. If your audio panel
requires 500 mV to drive it to full volume, then I'd expect the output with
72 mV to be about 17 dB below full output ... or in lay terms, "damned low".

There are several solutions, some better than others.

1. Call Garmin? (GMA-340) and ask them if you can clip a resistor that
provides the 510 ohm load for the input. For example, on the RST-564 audio
panel, we have a 560 ohm resistor on every audio input to ground to simulate
a standard 600 ohm load. If you clip that resistor out, the input impedance
jumps up to the value of the input summing resistor (10k)
(www.rstengineering.com and download schematics for the RST-564 -- drawing
564-5803). Problem solved. The main problem is to get Garmin? to give you
that data.

2. Failing that, you can kluge together a simple little single transistor
emitter follower amplifier that will take the 10K output impedance and
translate it directly to a 510 ohm input impedance. If somebody can tell me
how to post a binary to this group (no, I'm LOUSY at ascii schematic
artwork) or some other method of posting an image in the ra* groups, I'll be
happy to do so.

3. You can use the speaker output of the Alpine (if it has one) to drive
the audio panel directly ... unless it has what is called a "bridge
amplifier" and then we have to do a little dicking around (ahem, pardon me,
heuristic engineering) to get it to play properly.

There are more, but these are the easiest...

Jim



"Brian DeFord" > wrote in message
news:XhR8e.35465$A31.28773@fed1read03...
> Jim,
>
> I've read your columns regarding aircraft electronics for years and I just
> can't seem to get an answer for a problem I have. I'm trying to connect a
> Alpine AM/FM/CD player in my plane to the music input of my audio panel (a
> GMA340) The problem is that I can't hear the music
> because the volume is so low. I believe it has something to do with
> the input and output level of the two devices, but not being an
> electronics guru I don't know how I can make them work together. Do you
> have any suggestions? The output of the radio (pre-amplified) is 4V / 10K
> ohms max voltage and the audio panel music input is 510 ohm impedance and
> <500 mV RMS for full output typical, 1V AC RMS MAX (3V peak to peak).

[[email protected]]

I'd try an impedance matching transformer. Something like a Tamura
MET-17 (available from Digikey for about $20 each and other places).
If they do what you want, put heat shrink tubing around them and call
it a done deal.

Does your stereo or intercomm have a way of controlling the pre-amp
output volume of the music? You might be a little "hot" compared your
comm radio.

[RST Engineering]

You are kidding, aren't you?

Jim






> wrote in message
ups.com...
> I'd try an impedance matching transformer. Something like a Tamura
> MET-17 (available from Digikey for about $20 each and other places).
> If they do what you want, put heat shrink tubing around them and call
> it a done deal.
>
> Does your stereo or intercomm have a way of controlling the pre-amp
> output volume of the music? You might be a little "hot" compared your
> comm radio.
>

[[email protected]]

I'm absolutely serious, what's the issue?

Well since we're critiqing solutions...
1) I didn't like this one because you're asking the guy to take apart
his fancy audio panel (warrenty?). And there is a good chance that
resistor, if it exists, is a tiny surface mount part about the size of
a piece of pepper. Plus the solution only works for people who own the
same make/model audio panel.

2) I didn't like the emitter-follower amp because then you have to pull
(and breaker) power out to power the amps. His signal already has
enough power, its just the wrong impedance.

3) You might get away with this, but then again, as you alluded to,
that stereo may not like having its outputs connected to ground. Its
kind of a kludge to drive that 500 ohm input with an 8 (or less) ohm
output, there may be distortion because of the mismatch.


RST Engineering wrote:
> You are kidding, aren't you?
>
> Jim
>
>
>
>
>
>
> > wrote in message
> ups.com...
> > I'd try an impedance matching transformer. Something like a Tamura
> > MET-17 (available from Digikey for about $20 each and other
places).
> > If they do what you want, put heat shrink tubing around them and
call
> > it a done deal.
> >
> > Does your stereo or intercomm have a way of controlling the pre-amp
> > output volume of the music? You might be a little "hot" compared
your
> > comm radio.
> >

[RST Engineering]

> wrote in message
oups.com...
> I'm absolutely serious, what's the issue?
>
> Well since we're critiqing solutions...

Thankful we aren't crititquing spelling...


> 1) I didn't like this one because you're asking the guy to take apart
> his fancy audio panel (warrenty?). And there is a good chance that
> resistor, if it exists, is a tiny surface mount part about the size of
> a piece of pepper. Plus the solution only works for people who own the
> same make/model audio panel.


I'm not asking the guy to do anything. I'm simply pointing out how the
problem can be solved. You predicate surface mount, and even if it is, the
part is about the size of a matchhead, not a piece of pepper. So what if
the solution only is valid for that particular make/model of audio panel?
The general solution is valid for ALL audio panels, not just this
make/model. What don't you understand about generic solutions to problems?


>
> 2) I didn't like the emitter-follower amp because then you have to pull
> (and breaker) power out to power the amps. His signal already has
> enough power, its just the wrong impedance.

Didn't spend too much time in engineering school, didja? Do me a favor. Do
an Ohm's law calculation for the volts into 10K versus the volts into 500
ohms as a function of power. It isn't the wrong impedance, dunderhead, it
is not enough power to drive the requisite load. Your stupid suggestion of
a transformer indicates that you have not a clue about power transfer.



>
> 3) You might get away with this, but then again, as you alluded to,
> that stereo may not like having its outputs connected to ground. Its
> kind of a kludge to drive that 500 ohm input with an 8 (or less) ohm
> output, there may be distortion because of the mismatch.


Oh, bull****. Don't post here with this sort of stuff unless you've done it
before.


Jim

[Scott]

> Didn't spend too much time in engineering school, didja?

Oh here we go. Somebody dares to question the great Jim Weir and is going
to catch a rash of it. His next post will tell us again how many years he's
been doing electronics and how anybody not wanting to use their real name on
usenet is a coward.

Asking you for help on usenet is like calling into a radio talk show
psychologist. While the psychologist is usually right, the caller soon
becomes very sorry he asked.

[Darrel Toepfer]

Scott wrote:

>>Didn't spend too much time in engineering school, didja?
>
> Oh here we go. Somebody dares to question the great Jim Weir and is going
> to catch a rash of it. His next post will tell us again how many years he's
> been doing electronics and how anybody not wanting to use their real name on
> usenet is a coward.
>
> Asking you for help on usenet is like calling into a radio talk show
> psychologist. While the psychologist is usually right, the caller soon
> becomes very sorry he asked.

Yeah, I really hated it in school when the teachers made you think...

Shame they didn't do it more often...

[RST Engineering]

I answered the person asking for help straight up with several answers that
solved his problem. What is your beef with that?

If you are talking about the guy that answered without doing the homework,
what is your beef with that?


Jim

>
> Asking you for help on usenet is like calling into a radio talk show
> psychologist. While the psychologist is usually right, the caller soon
> becomes very sorry he asked.
>
>

[[email protected]]

Without all the name calling here's what I took about a minute to do:

Stereo preamp out: 4V, into 10K impedance
Audio panel input : 500mV, into 510ohm impedance.

Using formula :P=V^2/R I get

Stereo preamp outputs 1.6mW=2dBm
Audio panel plays full volume at .5mW= -3dBm

So we're in the ball park. You've got a little more power (about 5dB)
coming out of the preamp, but that's a a nice place to be because its
easy to lose power, hard to add it (you need to do crazy stuff like put
in amplifiers ;^) ).

Regarding formal engineering education, unless you're Dr. Weir, I win
that contest which really shouldn't be a requirement to participate in
a forum like this anyway.

[Scott]

> I answered the person asking for help straight up with several answers
that
> solved his problem. What is your beef with that?
>

Thankful we aren't crititquing spelling...
What don't you understand about generic solutions to problems?
Didn't spend too much time in engineering school, didja?
It isn't the wrong impedance, dunderhead
Your stupid suggestion of a transformer indicates that you have not a clue
Oh, bull****.


Do you listen to yourself ? You're a jerk, that's the problem.

[Montblack]

"Scott" <
> Asking you for help on usenet is like calling into a radio talk show
> psychologist. While the psychologist is usually right, the caller soon
> becomes very sorry he asked.


Ya, like when you're out on a ledge and they ask you if you can hold on
through the break?


Montblack

[RST Engineering]

Stereo preamp out is almost always given as volts peak-to-peak. The person
giving us the question stated that the audio panel input voltage was rms.
You will note that I converted into like units in my original post. If
Alpine DID give their output in RMS, then you will note that they are trying
to swing within less than a volt to the 12 volt rail and ground -- and I
can't conceive of any quality audio manufacturer trying to do that.

We can go either way, but the easy way is to convert the p-p to rms. 4V pp
= 1.4 volts RMS. 1.4^2 / 10E3 = 200 uW.

Audio panel plays full volume with 0.5^2 / 510 = 500 uW (in round numbers).

Seems to me we are just a bit short here. No transformer is 100% efficient,
so the problem gets worse as we go along. We start off life being down (10
log (500 uW/200uW)) (about -4 dB) and any passive solution simply adds to
the problem.

Let's give you the benefit of the doubt. Let's say that Alpine has their
act together and gave the output voltage as RMS. The equation then tells us
(as you noted) that we have 1.6 mW output and need 500 uW input, or an
excess of 5 dB. Let's see if we can practically do the solution you
propose.

You have to design for people who don't have access to their own transformer
factory as well as those in East Undershirt who only have access via mail
order, so let's examine the usual suspects.

Rat Shack has nothing of the kind.

Mouser has a few, the 42TU011 being the best of the bunch. However, if you
examine the curves of the transformer, you find that the frequency response
down in the bass is particularly terrible. The 3 dB points are given as 300
Hz and 3.4 kHz. respectively, so this great little Alpine tuner has turned
itself into a tin horn. I find that solution unacceptable.

Digi-Key is no joy, as is LKG/Philmore, Jameco, and half a dozen other
lesser lights.

One possible jury-rig solution may be to use a filament transformer as an
audio transformer to get the low frequency end, but if you have ever tried
this, you find that the high end falls off WELL before a couple of
kilohertz...lots of bass, but dearly lacking in treble. Not a solution.
Not only is it not a solution, but with a hunk of iron that will get down
into the tens of hertz range, you start picking up a fair amount of weight.
Remember, this is an AVIATION as well as an ELECTRONIC problem.

As to power, the fellow already needs to pick off power for both the tuner
and the audio panel. Stuffing a tiny single stage transistor impedance
converter inside either of these boxes and tying into the existing power
coming into the box isn't a great problem. NPN transistors can be had by
the bucketful at your local Hobby Shack store, as can a couple of resistors
and a couple of capacitors. Weight? A couple of ounces with enough left
over to stuff a flea's navel.

As to the Dr. Weir, no, I dropped out of the doctoral program when I
realized that what was being taught was roughly five to seven years behind
the stuff that I had already done. That wasn't what I wanted to waste my
time on ... and my own company wasn't going to pay me one cent more for a
doctorate. I'm the "dumb" one of the family; both my brothers have their
PhD.

I find your solution, while theoretically possible, to be difficult to
impossible to do practically.

Jim







> wrote in message
oups.com...
> Without all the name calling here's what I took about a minute to do:
>
> Stereo preamp out: 4V, into 10K impedance
> Audio panel input : 500mV, into 510ohm impedance.
>
> Using formula :P=V^2/R I get
>
> Stereo preamp outputs 1.6mW=2dBm
> Audio panel plays full volume at .5mW= -3dBm
>
> So we're in the ball park. You've got a little more power (about 5dB)
> coming out of the preamp, but that's a a nice place to be because its
> easy to lose power, hard to add it (you need to do crazy stuff like put
> in amplifiers ;^) ).
>
> Regarding formal engineering education, unless you're Dr. Weir, I win
> that contest which really shouldn't be a requirement to participate in
> a forum like this anyway.
>

[RST Engineering]

No, I expect and get answers like this from my students. I don't expect it
from a person who claims to know how to solve a problem without the briefest
nod towards a practical solution.

Jim



"Scott" > wrote in message
...
>
> Do you listen to yourself ? You're a jerk, that's the problem.
>
>

[[email protected]]

I thought it was pretty practical. I gave him a part number and
distributor.

When I read the tone of your response I thought must have said
something completely crazy so I went back and checked my numbers. If
the stereo voltage was RMS (the orginal post didn't state) then still
you're talking about .5mW vs. .2mW, and I assume a fancy audio panel
such as the Garmin one has some kind of level control to adjust the
user preference on music vs comms volume. You probably want the comm
radio to be louder than the music for safety sake.

The transformer I'd suggested is less than a half inch on a side, and
is +-2dB (pretty good for a headset in a GA airplane) from 300Hz out to
100KHz. The loss on those is really pretty good, can't be much more
than a dB.

Tacking together EF amps may be easy for someone like yourself (and
will totally work), but the layperson wants something he can take out
of the package and hook up (new RST product?).

[RST Engineering]

> wrote in message
oups.com...
>I thought it was pretty practical. I gave him a part number and
> distributor.

And a $20 price tag? You've gotta be kidding.


>
> When I read the tone of your response I thought must have said
> something completely crazy so I went back and checked my numbers. If
> the stereo voltage was RMS (the orginal post didn't state) then still
> you're talking about .5mW vs. .2mW,

If you go through my explanation, you will see that the most probable case
is that the stereo is peak-peak, not RMS. 4 volts RMS means that they are
operating with less than a half of a volt head-tail room on a 12 volt
battery bus. I really don't think Alpine would do that. Given p-p voltage,
you have a margin deficit of 4 dB.




and I assume a fancy audio panel
> such as the Garmin one has some kind of level control to adjust the
> user preference on music vs comms volume. You probably want the comm
> radio to be louder than the music for safety sake.

I'd bet cash money that it does not.


>
> The transformer I'd suggested is less than a half inch on a side, and
> is +-2dB

If you find a transformer with a power gain of 2 dB, you are in line for the
Nobel this year.


(pretty good for a headset in a GA airplane) from 300Hz out to
> 100KHz. The loss on those is really pretty good, can't be much more
> than a dB.

Falling off at 300 Hz. will make that sucker sound like a telephone. This
is a MUSIC application. And $20 for a transformer? Not in my bag of
tricks.


>
> Tacking together EF amps may be easy for someone like yourself (and
> will totally work), but the layperson wants something he can take out
> of the package and hook up (new RST product?).

In the first place, if I can get a two-week freshman engineering student to
be able to cobble one together in less than an hour, I think I can get
somebody with a little experience to do it in about the same amount of time.
In the second place, every (EVERY)thing that RST makes is in kit form, so
whether the guy buys the parts himself and nails them together or buys the
parts from me in a bag, the assembly process is identical. It isn't in my
vocabulary to put a two cent transistor, a couple of half-cent resistors,
and a couple of nickel capacitors in a bag and then have to charge $7 to
ship the sucker to him.

Jim
>

[Matt Whiting]

RST Engineering wrote:

> As to the Dr. Weir, no, I dropped out of the doctoral program when I
> realized that what was being taught was roughly five to seven years behind
> the stuff that I had already done. That wasn't what I wanted to waste my
> time on ... and my own company wasn't going to pay me one cent more for a
> doctorate. I'm the "dumb" one of the family; both my brothers have their
> PhD.

Dumb isn't lacking a Ph.D., it is having your own company. :-)

Matt

[Brian DeFord]

Jim,

I originally posted this, so I'll try to answer some of the
speculation. This is a copy of the Alpine CD spec from their web site -
same as the booklet I got with the radio:

GENERAL
Power Requirement 14.4 V DC
(11-16 V allowable)
Maximum Power Output 60 W =D7 4 (CDA-9815/
CDA-9813)
50W =D7 4 (CDA-9811)
Maximum Pre-Output Voltage 4 V/10 k ohms
Weight CDA-9815/CDA-9813
1=2E7 kg (3 lbs. 12 oz)

So as you can see they don't say wether the 4V is rms or not. The
Garmin unit did, so that's why I quoted the specs as I did.

As far as the circuit goes, I looked on the web for some help and came
across a site that appears to show the circuit you are talking about.
The site is:
http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/npncc.html#c3

and shows a diagram of the circuit. Is this the right one? If so, I
still need help (I'm not in the league one of the freshmen students you
refer to - sorry!) in determining the actual value of the resistors and
capacitors and transistor parts needed. I can make my way to Radio
Shack or Frys Electronics to buy the stuff and assemble it, but I just
don't have the background to determine the values. Thanks for your
help!
Brian

[Carl / KG6YKL]

Well guys, I started off annoyed that folks were arguing in a harsh
manner. However, after reading all of the posts I realized, you can
learn a lot from two engineers arguing. Keep up the good fight, just
put more smileys in there!

[Carl / KG6YKL]

RST Engineering wrote:

> jury-rig solution

Okay, this is way off topic but I have to know the history of this
expression. It is my understanding that the correct term is
"Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
"Jerry" for Japanese, used during WWII. The way it was told to me is
that near the end of WWII Jerry (the Japanese) were badly beaten and
much of their equipment was non-operational. However the Japanese
were very resourceful at doing whatever it took to get things working.
So people started talking about "Jerry-rigging" things.

Obviously the term "Jerry" is racially insensitive which probably led
to the alteration of the term. However, isn't "Jerryrigged" a
complimentary term when you consider it implies resourcefulness?
Lemmonaide from lemmons?

So, when I read Jim's post I did a quick Google search and found a
different explanation:

Most sources claim that the origin of the word jerryrig is unknown,
but William and Mary Morris, in Dictionary of Word and Phrase Origins
(see my bibliography), indicate that the term is likely a corrupted
form of juryrig, which referred to temporary rigging on a ship. Jury
as used in juryrig (which arose in the 17th century) likely comes from
Old French ajurie `help, relief.' The 'temporarily repair' sense
remained with the word juryrig, while its nautical roots faded away.
The vulgar expression to which you refer is likely patterned after
juryrig and jerryrig.

To say that something is "jerryrigged" is to mix idioms a bit,
because the proper term is "jerrybuilt." A "jerrybuilder," a term
dating to 19th-century England, was originally a house builder who
constructed flimsy homes from inferior materials. The "jerry" in the
term may have been a real person known for the practice, or may be a
mangled form of "jury," as in "jury-rigged." I tend to think that
"jerrybuilt" arose separately from "jury-rig" simply because their
senses are slightly different. Something that is "jury-rigged" is
concocted on the spur of the moment to meet an emergency, but
something "jerrybuilt" is deliberately constructed of inferior
materials to turn a quick buck.


So, what do folks out there think?

Carl.

PS- Isn't it strange what catches your interest sometimes?

[Robert Bonomi]

In article <ofC9e.56373$lz2.17509@fed1read07>,
Carl / KG6YKL > wrote:
>RST Engineering wrote:
>
>> jury-rig solution
>
>Okay, this is way off topic but I have to know the history of this
>expression. It is my understanding that the correct term is
>"Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
>"Jerry" for Japanese, used during WWII. The way it was told to me is
>that near the end of WWII Jerry (the Japanese) were badly beaten and
>much of their equipment was non-operational. However the Japanese
>were very resourceful at doing whatever it took to get things working.
>So people started talking about "Jerry-rigging" things.

All well and good, except for one fact. "Jerry" referred to the _Germans_,
not the Japanese.

Oh, yeah, a second "inconvenient" fact -- the term _was_ in use *before*
WWII.

>Obviously the term "Jerry" is racially insensitive which probably led
>to the alteration of the term.

Obviously "nonsense". <grin>

> However, isn't "Jerryrigged" a
>complimentary term when you consider it implies resourcefulness?

It's usually used in a mildly disparaging way -- implying an "ad hoc"
solution of a _temporary_ nature, and, thus, a lack of durability,
Something where it will be necessary to "come back later, and do it right".

In an _emergency_ situation, such methodologies are justified.
In a non-emergency, it's because somebody wasn't willing to expend
the effort to 'do it right' the _first_ time; with the expectation that
"somebody else" will be responsible for 'making it right' later.

Thus, the pejorative meaning -- because it is _usually_ applied to
"non-emergency" constructs.

[Ric]

"Richard Riley" > wrote in message
...
> On Wed, 20 Apr 2005 17:14:23 -0700, Carl / KG6YKL >
> wrote:
>
> :RST Engineering wrote:
> :
> :> jury-rig solution
> :
> :Okay, this is way off topic but I have to know the history of this
> :expression. It is my understanding that the correct term is
> :"Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
> :"Jerry" for Japanese, used during WWII. The way it was told to me is
> :that near the end of WWII Jerry (the Japanese) were badly beaten and
> :much of their equipment was non-operational. However the Japanese
> :were very resourceful at doing whatever it took to get things working.
> :So people started talking about "Jerry-rigging" things.
>
> 1) Jerry was the Germans, back to WW1
>
> 2) The Japanese were NOT very good at improvising. One of the
> problems of a strict hierarchical society. They were better than the
> Germans, but nowhere near as good as the Nebraska farm boys.
>
> 3) Look up Jury Strut. It's the secondary strut on a strut braced
> high wing aircraft. I don't know, but I'll bet its the same root.

I thought it something to do with large amounts of money turning up in the
accounts of 12 of your peers....

[Montblack]

("Carl / KG6YKL" wrote)
<snips>
> Obviously the term "Jerry" is racially insensitive which probably led to
> the alteration of the term. However, isn't "Jerryrigged" a complimentary
> term when you consider it implies resourcefulness? Lemmonaide from
> lemmons?

> So, what do folks out there think?


"Jerry" is not racially insensitive. Good Lord ..."obviously."

I don't know why these terms MUST always be assumed to be pejorative. Also,
wasn't Jerry used to talk about the Germans? Jerry Cans comes to mind.

Is Yank racially insensitive? If one person claims it is, is it? How about
Red, as in Red-baiting, or Red Army? How about playfully calling NHL hockey
players "Commies" who come from the former Eastern Block nations?
Pejorative? ...which (btw) is a word losing it's meaning these days.

Growing weary....

"Jerryrigging" is still OK - along with your toaster being on the Fritz
....still OK.

Piper names are hanging in there too - still OK.

We're losing color in our language as people try desperately to assign
victim status to virtually everyone, or anything. Good and Ungood isn't far
behind, which if it happens would be doubleplusungood!


Montblack
Little school kids now sit "noodle style" on the floor because some dolt
decided that "Indian style" was an offensive term. I would love to find out
that "noodle style" is preferred by kids because it sounds funny. Teachers,
however, are pushing it for racial sensitivity reasons.

[Dan, U.S. Air Force, retired]

Carl / KG6YKL wrote:

> RST Engineering wrote:
>
>> jury-rig solution
>
>
> Okay, this is way off topic but I have to know the history of this
> expression. It is my understanding that the correct term is
> "Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
> "Jerry" for Japanese, used during WWII.

Close, "jerry" was British slang for the Germans.

Dan, U. S. Air Force, retired

[Carl / KG6YKL]

Robert Bonomi wrote:

> All well and good, except for one fact. "Jerry" referred to the _Germans_,
> not the Japanese.

*blush* When I first started typing I was spelling it Gerryrigged
thinking it might be german but as I read the other web pages I
assumed they were right and changed it to Japanese. Well, I'll blame
my public education and lack of self-study.


> In an _emergency_ situation, such methodologies are justified.
This is the "positive" reference I was making.


So, now I will use Juryrigged with an understanding of the naval
reference.

[Carl / KG6YKL]

Richard Riley wrote:

> 2) The Japanese were NOT very good at improvising. One of the
> problems of a strict hierarchical society. They were better than the
> Germans, but nowhere near as good as the Nebraska farm boys.

The Nebraska farm boys experience tinkering with tractors, trucks, and
cars is credited with us adapting so well to mechanized warfare. They
already had much of the understanding & skills needed to fix trucks,
tanks, and aircraft. Their counterparts had likely never seen such
contrivances.

[Montblack]

("Richard Riley" wrote)
> 2) The Japanese were NOT very good at improvising. One of the
> problems of a strict hierarchical society. They were better than the
> Germans, but nowhere near as good as the Nebraska farm boys.


Odd, I would have given the mechanical tinkering edge to the German soldier
over a Japanese soldier. Maybe because German society had been
industrialized, on a number of levels, longer than Japan.


Montblack

[Montblack]

("Carl / KG6YKL" wrote)
<snip>
> Most sources claim that the origin of the word jerryrig is unknown, but
> William and Mary Morris, in Dictionary of Word and Phrase Origins (see my
> bibliography), indicate that the term is likely a corrupted form of
> juryrig, which referred to temporary rigging on a ship. Jury as used in
> juryrig (which arose in the 17th century) likely comes from Old French
> ajurie `help, relief.' The 'temporarily repair' sense remained with the
> word juryrig, while its nautical roots faded away. The vulgar expression
> to which you refer is likely patterned after juryrig and jerryrig.


I really enjoy the old nautical terms that are still used today - in one
form or another.


Montblack

[[email protected]]

On 20 Apr 2005 15:55:16 -0700, "Brian DeFord" >
wrote:

>Jim,
>
>I originally posted this, so I'll try to answer some of the
>speculation. This is a copy of the Alpine CD spec from their web site -
>same as the booklet I got with the radio:
>
>GENERAL
>Power Requirement 14.4 V DC
>(11-16 V allowable)
>Maximum Power Output 60 W × 4 (CDA-9815/
>CDA-9813)
>50W × 4 (CDA-9811)
>Maximum Pre-Output Voltage 4 V/10 k ohms
>Weight CDA-9815/CDA-9813
>1.7 kg (3 lbs. 12 oz)
>
>So as you can see they don't say wether the 4V is rms or not. The
>Garmin unit did, so that's why I quoted the specs as I did.
>
>As far as the circuit goes, I looked on the web for some help and came
>across a site that appears to show the circuit you are talking about.
>The site is:
>http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/npncc.html#c3
>
>and shows a diagram of the circuit. Is this the right one? If so, I
>still need help (I'm not in the league one of the freshmen students you
>refer to - sorry!) in determining the actual value of the resistors and
>capacitors and transistor parts needed. I can make my way to Radio
>Shack or Frys Electronics to buy the stuff and assemble it, but I just
>don't have the background to determine the values. Thanks for your
>help!
>Brian

Click on the "to numeric examples" and it gives values and how to
determine them.

[Netgeek]

"Matt Whiting" > wrote in message
...
> RST Engineering wrote:
>
> > As to the Dr. Weir, no, I dropped out of the doctoral program when I
> > realized that what was being taught was roughly five to seven years
behind
> > the stuff that I had already done. That wasn't what I wanted to waste
my
> > time on ... and my own company wasn't going to pay me one cent more for
a
> > doctorate. I'm the "dumb" one of the family; both my brothers have
their
> > PhD.
>
> Dumb isn't lacking a Ph.D., it is having your own company. :-)
>
> Matt

Amen.... (having been there).....

On the one hand:

B.S. = Bull ****
M.S. = More ****
PHD = Piled Higher and Deeper

But the truth is:

(Sung to the tune of the Mickey Mouse theme song)

M..I..T
P..H..D..
M..O..N..E..Y..!!!

8-)........................

[Netgeek]

"Carl / KG6YKL" > wrote in message
news:ofC9e.56373$lz2.17509@fed1read07...

<snip>

> So, what do folks out there think?

Carl,
I thought I was bad (and often obsessed) but - GEEZ - you really need
to get a life, my friend!!!!!!! 8-)........

Good luck and best regards,

Bill

[Matt Whiting]

Netgeek wrote:
> "Matt Whiting" > wrote in message
> ...
>
>>RST Engineering wrote:
>>
>>
>>>As to the Dr. Weir, no, I dropped out of the doctoral program when I
>>>realized that what was being taught was roughly five to seven years
>
> behind
>
>>>the stuff that I had already done. That wasn't what I wanted to waste
>
> my
>
>>>time on ... and my own company wasn't going to pay me one cent more for
>
> a
>
>>>doctorate. I'm the "dumb" one of the family; both my brothers have
>
> their
>
>>>PhD.
>>
>>Dumb isn't lacking a Ph.D., it is having your own company. :-)
>>
>>Matt
>
>
> Amen.... (having been there).....
>
> On the one hand:
>
> B.S. = Bull ****
> M.S. = More ****
> PHD = Piled Higher and Deeper
>
> But the truth is:
>
> (Sung to the tune of the Mickey Mouse theme song)
>
> M..I..T
> P..H..D..
> M..O..N..E..Y..!!!


Yes, but the sad part is that an MBA will get you even more money for
less upfront time investment.


Matt

[Brian DeFord]

>>As far as the circuit goes, I looked on the web for some help and came
>>across a site that appears to show the circuit you are talking about.
>>The site is:
>>http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/npncc.html#c3
>>
>>and shows a diagram of the circuit. Is this the right one? If so, I
>>still need help (I'm not in the league one of the freshmen students you
>>refer to - sorry!) in determining the actual value of the resistors and
>>capacitors and transistor parts needed. I can make my way to Radio
>>Shack or Frys Electronics to buy the stuff and assemble it, but I just
>>don't have the background to determine the values. Thanks for your
>>help!
>>Brian
>
>
> Click on the "to numeric examples" and it gives values and how to
> determine them.
>

Yes, for someone who knows what it's talking about - I don't even know
where to begin. It appears they come up with numbers from who knows
where and I don't think they start with the impedance and go from there.
That's my problem - I don't want to spend another day staring at those
equations only to get frustrated if someone could just tell me where to
begin!

Brian

[LCT Paintball]

doubleplusungood!


Isn't that making fun of overweight people? ;)

[RST Engineering]

Not a problem. If you are trying to make the transistor impedance
converter, and you have a Rat Shack 2N2222 or PN2222 or some other garden
variety NPN transistor ... then ...

Look at the "front" of the transistor. That's the "flat" side. Hold the
transistor with the flat side towards you and the wire leads down.

From the left to right, the leads are "emitter", "base", and "collector".
Don't worry about what the words mean right now.

You also have several inputs to this little amplifier. One is the +12
battery voltage. One is airframe ground. One is the Alpine audio output.
(The Alpine needs a common ground to airframe.)

The collector of the transistor goes directly to +12 battery supply (through
a LITTLE TINY fuse).

The emitter goes to ground through a 470 ohm resistor.

There is a 47K resistor going from the collector to base. There is a 47K
resistor going from base to ground.

There is a 100 nF capacitor (0.1 uF) from the Alpine audio output to the
base of the transistor.

There is a 10 uF capacitor from the emitter of the transistor to the input
of the audio panel. This will undoubtedly be an electrolytic, so the (+)
lead of the capacitor is to the emitter of the transistor and the (-) lead
is to the audio panel.

Did that help?


Jim





>
> Yes, for someone who knows what it's talking about - I don't even know
> where to begin. It appears they come up with numbers from who knows where
> and I don't think they start with the impedance and go from there. That's
> my problem - I don't want to spend another day staring at those equations
> only to get frustrated if someone could just tell me where to begin!
>
> Brian

[Brian DeFord]

RST Engineering wrote:
> Not a problem. If you are trying to make the transistor impedance
> converter, and you have a Rat Shack 2N2222 or PN2222 or some other garden
> variety NPN transistor ... then ...
>
> Look at the "front" of the transistor. That's the "flat" side. Hold the
> transistor with the flat side towards you and the wire leads down.
>
> From the left to right, the leads are "emitter", "base", and "collector".
> Don't worry about what the words mean right now.
>
> You also have several inputs to this little amplifier. One is the +12
> battery voltage. One is airframe ground. One is the Alpine audio output.
> (The Alpine needs a common ground to airframe.)
>
> The collector of the transistor goes directly to +12 battery supply (through
> a LITTLE TINY fuse).
>
> The emitter goes to ground through a 470 ohm resistor.
>
> There is a 47K resistor going from the collector to base. There is a 47K
> resistor going from base to ground.
>
> There is a 100 nF capacitor (0.1 uF) from the Alpine audio output to the
> base of the transistor.
>
> There is a 10 uF capacitor from the emitter of the transistor to the input
> of the audio panel. This will undoubtedly be an electrolytic, so the (+)
> lead of the capacitor is to the emitter of the transistor and the (-) lead
> is to the audio panel.
>
> Did that help?

Thanks you very much!!! That is a BIG help. Thank you for taking the
time to do this. I'll let you know how it turns out!

Regards,
Brian

[Brian DeFord]

RST Engineering wrote:
> Not a problem. If you are trying to make the transistor impedance
> converter, and you have a Rat Shack 2N2222 or PN2222 or some other garden
> variety NPN transistor ... then ...
>
> Look at the "front" of the transistor. That's the "flat" side. Hold the
> transistor with the flat side towards you and the wire leads down.
>
> From the left to right, the leads are "emitter", "base", and "collector".
> Don't worry about what the words mean right now.
>
> You also have several inputs to this little amplifier. One is the +12
> battery voltage. One is airframe ground. One is the Alpine audio output.
> (The Alpine needs a common ground to airframe.)
>
> The collector of the transistor goes directly to +12 battery supply (through
> a LITTLE TINY fuse).
>
> The emitter goes to ground through a 470 ohm resistor.
>
> There is a 47K resistor going from the collector to base. There is a 47K
> resistor going from base to ground.
>
> There is a 100 nF capacitor (0.1 uF) from the Alpine audio output to the
> base of the transistor.
>
> There is a 10 uF capacitor from the emitter of the transistor to the input
> of the audio panel. This will undoubtedly be an electrolytic, so the (+)
> lead of the capacitor is to the emitter of the transistor and the (-) lead
> is to the audio panel.
>
Jim,

So what did you assume for the Alpine's voltage in coming up with these
numbers; 4V rms or p-p? Speaking to a friend of mine today, he's
positive it is rms.

Brian

[Highflyer]

"Carl / KG6YKL" > wrote in message
news:ofC9e.56373$lz2.17509@fed1read07...
> RST Engineering wrote:
>
>> jury-rig solution

jury-rig is correct and is a nautical term meaning to make a temporary
repair using available materials to solve a problem.

>
> Okay, this is way off topic but I have to know the history of this
> expression. It is my understanding that the correct term is
> "Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
> "Jerry" for Japanese, used during WWII. The way it was told to me is that
> near the end of WWII Jerry (the Japanese) were badly beaten and much of
> their equipment was non-operational. However the Japanese were very
> resourceful at doing whatever it took to get things working. So people
> started talking about "Jerry-rigging" things.


In WWII the Germans were "jerrys" while the Japanese were "nips."


>
> Obviously the term "Jerry" is racially insensitive which probably led to
> the alteration of the term. However, isn't "Jerryrigged" a complimentary
> term when you consider it implies resourcefulness? Lemmonaide from
> lemmons?
>
> So, when I read Jim's post I did a quick Google search and found a
> different explanation:
>
> Most sources claim that the origin of the word jerryrig is unknown, but
> William and Mary Morris, in Dictionary of Word and Phrase Origins (see my
> bibliography), indicate that the term is likely a corrupted form of
> juryrig, which referred to temporary rigging on a ship. Jury as used in
> juryrig (which arose in the 17th century) likely comes from Old French
> ajurie `help, relief.' The 'temporarily repair' sense remained with the
> word juryrig, while its nautical roots faded away. The vulgar expression
> to which you refer is likely patterned after juryrig and jerryrig.
>
> To say that something is "jerryrigged" is to mix idioms a bit, because
> the proper term is "jerrybuilt." A "jerrybuilder," a term dating to
> 19th-century England, was originally a house builder who constructed
> flimsy homes from inferior materials. The "jerry" in the term may have
> been a real person known for the practice, or may be a mangled form of
> "jury," as in "jury-rigged." I tend to think that "jerrybuilt" arose
> separately from "jury-rig" simply because their senses are slightly
> different. Something that is "jury-rigged" is concocted on the spur of the
> moment to meet an emergency, but something "jerrybuilt" is deliberately
> constructed of inferior materials to turn a quick buck.
>
>
> So, what do folks out there think?
>
> Carl.
>
> PS- Isn't it strange what catches your interest sometimes?

[Ron Natalie]

Highflyer wrote:
> "Carl / KG6YKL" > wrote in message
> news:ofC9e.56373$lz2.17509@fed1read07...
>
>>RST Engineering wrote:
>>
>>
>>>jury-rig solution
>
>
> jury-rig is correct and is a nautical term meaning to make a temporary
> repair using available materials to solve a problem.
>
>
>>Okay, this is way off topic but I have to know the history of this
>>expression. It is my understanding that the correct term is
>>"Jerry-rigged" or "Jerryrigged" which is based on the pejorative term
>>"Jerry" for Japanese, used during WWII. The way it was told to me is that
>>near the end of WWII Jerry (the Japanese) were badly beaten and much of
>>their equipment was non-operational. However the Japanese were very
>>resourceful at doing whatever it took to get things working. So people
>>started talking about "Jerry-rigging" things.
>

I guess consulting a dictionary was out of the question? Anyhow, it
goes back to way before WWII. It's old nautical slang.

The term from the American Heritage Dictionary of the English Language says:
From jury-rig, jury-rigging, improved rigging on a ship, modeled on
jury-mast, temporary mast, perhaps untimely from Old French ajure, help,
from aider, to help.

The OED finds reference to jury mast as far back as the year 1616. The
first use of Jury rig is in 1788. The OED doesn't give credance to the
French derivation however, it also notes the unsupported suggestion that
it is a corruption of "injury".

[[email protected]]

There's a post in rec.aviation.ifr titled "Garmin GMA 340 Music Input"
that I found by accident while trying to find the melee I got caught up
in. In it someone is describing using transformers (from "RatShack" no
less) to impedance match a line level output to his Garmin 340 input.
Apparently it worked out for that guy. So if you haven't selected and
biased your transistors yet, check it out.