Cockpit Audio wiring (hyjacked from "gear warning")

[Bill Daniels]

"Mike Lindsay" > wrote in message
...
> In article <DdqdnYPHoYf1J-benZ2dnUVZ_v
Snip-------
> We put in a new vario this year, the only snag was we had
> nowhere to put the speaker except behind the panel. We thought we could
> do with a bit more audio. I remembered our radio, a Dittel clone, has an
> input for an intercom. We fed the audio from the vario into the radio,
> and now we have all the volume we need.
>
>
> --
> Mike Lindsay

Mike, that's interesting. Did the radio squelch the vario audio when
transmitting and receiving?

A quick check of my Microair 760 manual shows that Pin 14 is "Music in" on
the DB15 connector. Now, I'm not going to connect a $1000 vario to a $1000
radio without some specific guidance from the respective manufacturers but
that's a cool idea. The audio from the little pizeo squeekers that come
with the Borgelt instruments isn't that great (Even Mike B suggests that
there are better speakers.) and it would be nice to squelch the vario audio
when using the radio.

Bill Daniels

[Mike the Strike]

This is probably one of the best suggestions I've heard in a long time
on RAS - feeding the vario audio to the radio intercom input so that
it's squelched when transmitting. It would be a lot easier for my old
ears to have the speaker behind my head double for this function rather
than the wimpy vario speaker in the panel.

Mike

[Bill Daniels]

"Mike the Strike" > wrote in message
oups.com...
> This is probably one of the best suggestions I've heard in a long time
> on RAS - feeding the vario audio to the radio intercom input so that
> it's squelched when transmitting. It would be a lot easier for my old
> ears to have the speaker behind my head double for this function rather
> than the wimpy vario speaker in the panel.
>
> Mike
>

Been RTFMs again.

The B50 expects to see an 8 ohm speaker load and the M760 expects to see
100mw at 600 ohms on the 'music' input. Any 'sparkies' with an opinion on
how to match up these devices?

Bill Daniels

[Mike Lindsay]

In article >, Bill Daniels
> writes
>
>Been RTFMs again.
>
>The B50 expects to see an 8 ohm speaker load and the M760 expects to see
>100mw at 600 ohms on the 'music' input. Any 'sparkies' with an opinion on
>how to match up these devices?
>
>Bill Daniels
>
I'm not a sparkie, but if you have an 8 ohm speaker it will have
about 0.5 volts of audio across it when sounding. At this low impedance
that will be enough for the radio. It wouldn't work if you fed a high
impedance output into a low impedance input, but its fine this way
round.

My calculation suggests for full output from the music input
you'd need getting on for 8 volts of AC but I expect that'd be enough
volume for a disco.
--
Mike Lindsay

[Andy]

"and it would be nice to squelch the vario audio
when using the radio. "

Why?? One of the great pleasures of cross country is to key the mic
from a 10k thermal when you know your competitors looking at the dirt.

Andy

[01-- Zero One]

"Andy" > wrote in message
oups.com:

> "and it would be nice to squelch the vario audio
> when using the radio. "
>
> Why?? One of the great pleasures of cross country is to key the mic
> from a 10k thermal when you know your competitors looking at the dirt.
>
> Andy



Exactly, Andy!!!



How many times have you postponed a radio call a few seconds until you
were in the "hot" side of the thermal so everyone could hear a faster
pitched audio vario? ;-)



Larry

[Ian]

On Fri, 18 Nov 2005 08:04:22 -0800, Mike the Strike wrote:

> This is probably one of the best suggestions I've heard in a long time
> on RAS - feeding the vario audio to the radio intercom input so that
> it's squelched when transmitting.

No, it would spoil the fun. Then you can't center a decent thermal, push
the ptt and let your buddies listen enviously to a high pitched
"tweet-tweet-tweet" for a few seconds before you start blabbing into the
mic.


Ian

[Mark A. Matthews]

In article >,
"Bill Daniels" > wrote:
> The B50 expects to see an 8 ohm speaker load and the M760 expects to see
> 100mw at 600 ohms on the 'music' input. Any 'sparkies' with an opinion on
> how to match up these devices?

If the B50 provided an unbalanced output (one side of the speaker is
returned to ground, just hook them up. It will work fine.

If the B50 puts out a balanced output (speaker floats, not connected to
ground), go by your neighborhood Radio Shack ("You have questions, we
have blank stares") and get a 273-1380 audio output transformer. Hook
the 8 ohm side to the B50 and one-half the 1K ohm side to the M760.

[JS]

What an excellent thread.
Mark's Radio Crap transformer and a couple of resistors, and you're
laughing!
The vario automute function has a side benefit of keeping us off the
radio until we have the thermal centered at 14 knots, allowing
concentration on silly things like not hitting anybody else on entry.
Alle ist wunderbar in segelflugland.
Jim

[[email protected]]

If cutting the vario when the mic is keyed is the objective, could the
PTT be wired to cause a relay to open the vario speaker circuit? Then
the technique could be used with any radio?

[Bill Daniels]

"01-- Zero One" > wrote in message
...
"Andy" > wrote in message
oups.com:

> "and it would be nice to squelch the vario audio
> when using the radio. "
>
> Why?? One of the great pleasures of cross country is to key the mic
> from a 10k thermal when you know your competitors looking at the dirt.
>
> Andy

Exactly, Andy!!!

How many times have you postponed a radio call a few seconds until you were
in the "hot" side of the thermal so everyone could hear a faster pitched
audio vario? ;-)

Larry


I get really annoyed with endless "vario reports". Everybody in the air
probably already knows the typical thermal strengths and, if they aren't
playing with the radio, they've probably already cored a better thermal.
If you want to play with radios, get a HAM license.

The glider frequencies are so congested that it's often hard to hear really
important messages. If I am going to transmit, I want a clear, quiet
channel so I don't have to repeat the transmission. A pilot shouldn't be
forced to use a cellphone to contact his crew.

Squelching the vario audio is a good thing since a loud vario in the
background can saturate the transmitter and garble the message. Mixing the
vario audio through the radio takes advantage of a much better amplifier and
speaker than the vario has.

Bill Daniels

[Eric Greenwell]

wrote:
> If cutting the vario when the mic is keyed is the objective, could the
> PTT be wired to cause a relay to open the vario speaker circuit? Then
> the technique could be used with any radio?

Sure! I'd suggest using a small DPDT ("double pole, double throw") relay
(check Radio Shack) behind the panel. One set of contacts would key the
radio; the other set of contacts would open the lead to the vario speaker.

The coil would be driven by the PTT switch. A 12 volt coil would work as
long as it closes with 10 volts or less, because you don't want the
radio to stop working just because you can't key it. If you are
concerned about this, you could mount a PTT switch on the panel that is
in parallel with the contacts to the radio, for use if the relay fails.
You might have to use a relay with a lower voltage coil and use a
resistor in series with it, or carefully adjust the metal tab holding
the contact spring.

A small diode should be placed across the coil to protect the PTT
contacts. Connect the diode so current does not flow through it when the
PTT is keyed; i.e., the band on the diode body should connect to the
positive side of the coil.

Undoubtedly, your club has a member that can assist you, if needed.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Bob Korves]

Eric Greenwell > wrote in
:

> wrote:
>> If cutting the vario when the mic is keyed is the objective, could
>> the PTT be wired to cause a relay to open the vario speaker circuit?
>> Then the technique could be used with any radio?
>
> Sure! I'd suggest using a small DPDT ("double pole, double throw")
> relay (check Radio Shack) behind the panel. One set of contacts would
> key the radio; the other set of contacts would open the lead to the
> vario speaker.
>
> The coil would be driven by the PTT switch. A 12 volt coil would work
> as long as it closes with 10 volts or less, because you don't want the
> radio to stop working just because you can't key it. If you are
> concerned about this, you could mount a PTT switch on the panel that
> is in parallel with the contacts to the radio, for use if the relay
> fails. You might have to use a relay with a lower voltage coil and use
> a resistor in series with it, or carefully adjust the metal tab
> holding the contact spring.
>
> A small diode should be placed across the coil to protect the PTT
> contacts. Connect the diode so current does not flow through it when
> the PTT is keyed; i.e., the band on the diode body should connect to
> the positive side of the coil.
>
> Undoubtedly, your club has a member that can assist you, if needed.
>

You could also use a DPDT PTT switch on the stick to control both
functions. A SPST PTT switch with both NO and NC contacts would probably
do the job, too. This would eliminate the relay and diode and the extra
complication and current draw, reducing potential failure points at the
expense of routing more wires to the PTT. KISS. :-)
-Bob Korves

[Eric Greenwell]

Bob Korves wrote:

>>Undoubtedly, your club has a member that can assist you, if needed.
>>
>
>
> You could also use a DPDT PTT switch on the stick to control both
> functions.

This would work fine. In my glider, changing the switch and running the
extra wire would be more trouble than the relay, but it might be an
easier choice for Mr. Lepp.

> A SPST PTT switch with both NO and NC contacts

That would make it a SPDT switch. It probably is one, already, but
another wire might be needed.

> would probably
> do the job, too. This would eliminate the relay and diode and the extra
> complication and current draw, reducing potential failure points at the
> expense of routing more wires to the PTT. KISS. :-)

This method would work fine if your vario uses a grounded speaker. Some
require a "floating" speaker, like the Cambridge 302.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Martin Gregorie]

Bill Daniels wrote:
..../...

> I get really annoyed with endless "vario reports". Everybody in the air
> probably already knows the typical thermal strengths and, if they aren't
> playing with the radio, they've probably already cored a better thermal.
> If you want to play with radios, get a HAM license.
>
The only disadvantage of this idea that I can see is that you loose the
vario sound if you turn the radio off or down to get rid of annoying
chatter.

For that reason alone I prefer the idea of a separate audio amp with
inputs for the radio and vario (and warning horns?).

--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[Bill Daniels]

"Martin Gregorie" > wrote in message
...
> Bill Daniels wrote:
> .../...
>
> > I get really annoyed with endless "vario reports". Everybody in the air
> > probably already knows the typical thermal strengths and, if they aren't
> > playing with the radio, they've probably already cored a better thermal.
> > If you want to play with radios, get a HAM license.
> >
> The only disadvantage of this idea that I can see is that you loose the
> vario sound if you turn the radio off or down to get rid of annoying
> chatter.
>
> For that reason alone I prefer the idea of a separate audio amp with
> inputs for the radio and vario (and warning horns?).
>
Any ideas on where to get one?

Bill Daniels

[Martin Gregorie]

Bill Daniels wrote:
> "Martin Gregorie" > wrote in message
> ...
.../..

>> For that reason alone I prefer the idea of a separate audio amp with
>> inputs for the radio and vario (and warning horns?).
>>
> Any ideas on where to get one?
>
No, unfortunately. But, maybe, if enough of us say "I want one" in
chorus the people at Tasmin will pick up on it and offer the extra
inputs on their gear up warning box.

--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[Mike Lindsay]

In article . com>,
writes
>If cutting the vario when the mic is keyed is the objective, could the
>PTT be wired to cause a relay to open the vario speaker circuit? Then
>the technique could be used with any radio?
>
I had to do something like that with my last glider.

If the A/H was running when I used the radio, nobody could hear anything
except hash from the inverter. So I arranged a relay switched by the PTT
to cut off the inverter. That sorted it.
After all, it doesn't take more than a second to announce you are going
into cloud.
--
Mike Lindsay