Audio Circuit

Hi Folks,
I am hunting for a reference design for or to purchase outright a
circuit board which will allow the combination of several audio signals
into an aux audio connection. (I am sure this has been hashed out here
in the past, but my searches on this group didn't end my cluelessness)

The particulars:

1. Single seat aircraft
No intercom or audio panel

2. Becker 4201 Comm
Aux audio input:
---Snipped from manual 23-10-01 of the Becker 4201- SN 1K and up--

"Auxiliary" audio input
The AF-AUX (P1/4) auxiliary audio input enables the switching of audio
signals from other equipment in the aircraft. The switched-in audio
signals can, however, only be monitored in the reception mode. The
facility to switch two units together will be used particularly in those
aircraft which are fitted with an Transceiver and an NAV receiver. An
audio input voltage of 1 to 8 V, 600 Ohm is necessary for modulation of
the audio audio amplifier (can be adjusted in the "Service" mode).

Audio auxiliary input
A second and third radio unit (navigation receiver) can be monitored
simultaneously via the audio auxiliary input. During transmission the
auxiliary input is switched off from the audio end amplifier. If
necessary, the input sensitivity can be matched to the noise level of
the aircraft (for setting refer to service mode).

-------------------------------------------

3. Several audio inputs:
AOA, EFIS(various warnings), EIS, gear warning, IPOD, (maybe another)

My goal is to integrate all of the audio inputs independently into a
well designed circuit board. Then have one input into the aux audio
port of the Becker 4201.


Jim Weir in Dec 06 issue of Kitplanes introduced and outlined the use of
OPAMP Circuits to integrate these systems. It is this technology I
believe is appropriate for my integration needs.


Before I begin to hack together my own circuit, is there a solid
reference design out there from which I can build? Any guidance is
greatly appreciated.

Ken

Ken: I took Jim Weir's circuits, modified them and came up with my own
Isolation amp circuit that has built in tone code oscillators for a low and
a high rotor alarm, the radio audio and the intercom audio input. Jim's
circuit can pretty much be modified for just about any number of audio
inputs. I had a priority override of the rotor alarms for awhile which shut
off the radio and intercom with the idea that "Fly first, Communicate
Second". I've changed that now and just mix all the signals. The output
goes to the headphones. I've been flying the system for about 8-9 years and
have built several for other helicopters. I did the printed circuit board
via PCB Express. If you have the circuit, they can pretty much generate
your pcb with a double sided board with plated thru holes and the price for
a small board is about $60. for three boards.
Stuart Fields
Experimental Helo magazine


"Ken Gage" wrote in message
...
Hi Folks,
I am hunting for a reference design for or to purchase outright a circuit
board which will allow the combination of several audio signals into an
aux audio connection. (I am sure this has been hashed out here in the
past, but my searches on this group didn't end my cluelessness)

The particulars:

1. Single seat aircraft
No intercom or audio panel

2. Becker 4201 Comm
Aux audio input:
---Snipped from manual 23-10-01 of the Becker 4201- SN 1K and up--

"Auxiliary" audio input
The AF-AUX (P1/4) auxiliary audio input enables the switching of audio
signals from other equipment in the aircraft. The switched-in audio
signals can, however, only be monitored in the reception mode. The
facility to switch two units together will be used particularly in those
aircraft which are fitted with an Transceiver and an NAV receiver. An
audio input voltage of 1 to 8 V, 600 Ohm is necessary for modulation of
the audio audio amplifier (can be adjusted in the "Service" mode).

Audio auxiliary input
A second and third radio unit (navigation receiver) can be monitored
simultaneously via the audio auxiliary input. During transmission the
auxiliary input is switched off from the audio end amplifier. If
necessary, the input sensitivity can be matched to the noise level of the
aircraft (for setting refer to service mode).

-------------------------------------------

3. Several audio inputs:
AOA, EFIS(various warnings), EIS, gear warning, IPOD, (maybe another)

My goal is to integrate all of the audio inputs independently into a well
designed circuit board. Then have one input into the aux audio port of
the Becker 4201.


Jim Weir in Dec 06 issue of Kitplanes introduced and outlined the use of
OPAMP Circuits to integrate these systems. It is this technology I
believe is appropriate for my integration needs.


Before I begin to hack together my own circuit, is there a solid reference
design out there from which I can build? Any guidance is greatly
appreciated.

Ken

Ken Gage wrote:
Hi Folks,
I am hunting for a reference design for or to purchase outright a
circuit board which will allow the combination of several audio signals
into an aux audio connection. (I am sure this has been hashed out here
in the past, but my searches on this group didn't end my cluelessness)

The particulars:

1. Single seat aircraft
No intercom or audio panel

2. Becker 4201 Comm
Aux audio input:
---Snipped from manual 23-10-01 of the Becker 4201- SN 1K and up--

"Auxiliary" audio input
The AF-AUX (P1/4) auxiliary audio input enables the switching of audio
signals from other equipment in the aircraft. The switched-in audio
signals can, however, only be monitored in the reception mode. The
facility to switch two units together will be used particularly in those
aircraft which are fitted with an Transceiver and an NAV receiver. An
audio input voltage of 1 to 8 V, 600 Ohm is necessary for modulation of
the audio audio amplifier (can be adjusted in the "Service" mode).

Audio auxiliary input
A second and third radio unit (navigation receiver) can be monitored
simultaneously via the audio auxiliary input. During transmission the
auxiliary input is switched off from the audio end amplifier. If
necessary, the input sensitivity can be matched to the noise level of
the aircraft (for setting refer to service mode).

-------------------------------------------

3. Several audio inputs:
AOA, EFIS(various warnings), EIS, gear warning, IPOD, (maybe another)

My goal is to integrate all of the audio inputs independently into a
well designed circuit board. Then have one input into the aux audio
port of the Becker 4201.


Jim Weir in Dec 06 issue of Kitplanes introduced and outlined the use of
OPAMP Circuits to integrate these systems. It is this technology I
believe is appropriate for my integration needs.


Before I begin to hack together my own circuit, is there a solid
reference design out there from which I can build? Any guidance is
greatly appreciated.

Ken
http://aeroelectric.com/Catalog/AECcatalog.html

scroll down near the bottom for the iso amp board.

A bare circuit board for $22 is fairly pricey but not beyond reasonable.
However, if a "sorta-kit" with bare board AND all components (less case or
chassis) were available for $35 or so, how would that fly in Peoria?

BTW, a board like this, in 100 quantities can be had for about $4 or so from
a dozen manufacturers, some in Utah, some in Colorado, some in Taiwan, some
on mainland China, some in Bulgaria...

As a companion to that, let me tell you from 35 years of experience putting
things like this out what the problems are going to be:

1. You made it stereo, I want mono.

2. You made it mono, I want stereo.

3. It doesn't work with my 1956 Mark 12 Belchfire radios.

4. Please email me a .pdf of how to turn this into a full house audio
panel.

5. I broke a lead off of the integrated circuit. Will it still work?

6. OK, then, can you send me one by FedEx overnight? My plane needs to fly
tomorrow (notwithstanding the fact that it has been 18 years in the making).

7. I need one more input than you supply. Can you just sketch me up the
details of how to add another channel and email a .pdf to me?

8. And can you send me the parts for this mod FedEx overn....

9. Why is the circuit board green? I want blue.

10. I bought this thing of yours off of ebay and it doesn't work. Where do
I send it to have your warranty service performed?

11. And if you don't do 1-10 as your first priority you are a miserable
scumbag not fit to sell parts to the aviation community.

(To be taken with a grain of salt...although I have answered 1-9 numerous
times over the years and #10 more times than I care to count.)

Jim


Ken Gage wrote:



Before I begin to hack together my own circuit, is there a solid
reference design out there from which I can build? Any guidance is
greatly appreciated.

Ken

On Apr 7, 12:48 pm, "RST Engineering" wrote:
A bare circuit board for $22 is fairly pricey but not beyond reasonable.
However, if a "sorta-kit" with bare board AND all components (less case or
chassis) were available for $35 or so, how would that fly in Peoria?


Having just gone through the tedious process of collecting all the
pieces necessary to make a capacitive fuel tank sensor that doesn't
work, I would HAPPILY pay $35 to have all the pieces collected
together. There would be some comfort in knowing that someone has
done the difficult work of verifying that all the parts are present,
the tolerances work out, and the circuit has some hope of working. I
bet I spent over 4 hours ordering less than 50 pieces. Digikey put
each in an indiviual box and then put them all in a really large box.
My $20 worth of pieces ended up costing me $35 once the shipping was
added in. A $.04 resistor only cost $.04 when you buy a roll.

I also made my own circuit board. It was a fun exercise, but time
consuming. Once I learned the circuit layout package, etched a board,
discovered all my errors (it's not always obvious which side a trace
MUST be on), etched two more iterations...I've got dozens of hours
tied up. I'm sure I'll be able to make circuits with this method in
the future. It's fun and rewarding. But if someone has a board
avaible for around $20, it's hard to justify the effort.

wrote

On Apr 7, 12:48 pm, "RST Engineering" wrote:
A bare circuit board for $22 is fairly pricey but not beyond reasonable.
However, if a "sorta-kit" with bare board AND all components (less case
or
chassis) were available for $35 or so, how would that fly in Peoria?


Having just gone through the tedious process of collecting all the
pieces necessary to make a capacitive fuel tank sensor that doesn't
work, I would HAPPILY pay $35 to have all the pieces collected
together.

Me too! I have just paid for such a beast, i.e. a battery desulfinator.

I can do lots of things, but understanding electronics is not one of them.

I do know which end of a soldering iron to hold, and if someone tells me to
put tab a into hole b and apply solder, I can do that.

So yes, gather everything, and give a good set of instructions, and it would
be "more better."
--
Jim in NC

I have just paid for such a beast, i.e. a battery desulfinator.
--
Jim in NC
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Battery desulfinator, eh?

Can hardly wait for the hard core testimonies
concerning all the batteries that have been
undisputedly desulfated & resurrected...

Like me from Muzzleloader.


- Barnyard BOb -

"Barnyard BOb" wrote

Battery desulfinator, eh?

Can hardly wait for the hard core testimonies
concerning all the batteries that have been
undisputedly desulfated & resurrected...

Like me from Muzzleloader.

Ahhh, I don't think so.

Desulfinating battery plates are a simple matter of science.

Raising you from the dead was a miracle....I think.

Is it right to call a mistaken action, a miracle? g

Not to call you a mistake, mind you! :-)
--
Jim in NC

"Morgans" wrote:

Desulfinating battery plates are a simple matter of science.

Oh ****!

When science is reduced so cavalierly as to be a"SIMPLE MATTER"....
one of two things usually rings true.

Either one is a bona fide chemical/electronics expert or...
one could not be more ignorant or legendary in their own mind.

To identify which class prevails here, please articulate
this dirt "simple science" for the uneducated masses.

Also....
1. How much experience do you have"desulfinating"?
2. Please describe your DESULFINATOR in some detail.

Have you read Jim Weir's SULFATE BUSTER article....
http://www.rst-engr.com/kitplanes/KP0204/KPtext.pdf

P.S.
My success resuscitating lead acid batteries is 'spotty' at best.
The investment in time, effort, materials and money spent replacing
'holey clothes' has convinced me to BE PRACTICAL and just limit my
input to TLC until a faithful battery has died a natural death....
then, just 'SIMPLY' replace it. :-)

Your mileage may vary.


- BOb -

"Barnyard BOb" wrote

My success resuscitating lead acid batteries is 'spotty' at best.
The investment in time, effort, materials and money spent replacing
'holey clothes' has convinced me to BE PRACTICAL and just limit my
input to TLC until a faithful battery has died a natural death....
then, just 'SIMPLY' replace it. :-)

Your mileage may vary.

First, let me say that it was "simple" was partially a poke at comparing the
complexity of doing something like raising a former ag pilot from the dead.

I have no great hope of getting long dead batteries working again, or
getting batteries to live twice as long as they would be expected to live,
or any other miracles of those types.

It would be nice to keep the batteries performing a little better in the
waning months of their lives. I have a lawn mower with a battery that
always seem to die early, and I hope I could get it to live longer.

Any other benefits I get from it will be gravy. It was cheap, and something
else to fiddle with. End of story, on my motivations for getting it.

Long ago, my college job involved large battery powered pallet movers. They
would be overcharged occasionally, or acid was somehow spilled on the
outside of the machine, and would then dry up. If one were to brush up
against one of these machines, and transfer some of the crystal acid onto
their clothes, it would not be noticeable, immediately.

When the clothes got washed, the acid was re-animated by the washer, and
would come out a mere shell of their former shape. :-)
--
Jim in NC