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

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.

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.

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.

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

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.

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...

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.

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.

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.

"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