Re: Jim Weir question - Comtronics helmet adaptor?

[Cy Galley]

I believe Comtronics has a web site. Why not ask the maker?


"Richard Riley" > wrote in message
...
>I have a new Comtronics "Ultra Pro 2000" (doncha love that name?)
> helmet/headset. It's output is a single 1/4" plug with 3 contact
> bands. When I stick it in the phone jack on an intercom I can hear
> but (not surprisingly) can't transmit.
>
> I need to make a little adaptor to go from that to a standard 2 plug
> output so I can plug into my dull old standard patch cable for an Icom
> handheld.
>
> I was thinking you may have already written an article on how to do
> that. Got anything lying around, or any advice before I start?
>
> Thanks.

[RST Engineering]

That's because it ain't $120 worth of jacks and wire. It is $120 worth of
amplifier that takes those few millivolts of microphone audio, uses the bias
voltage coming down the aircraft radio mic audio line, smooths that voltage
into a working voltage for an amplifier, and provides an amplifier that
takes those millivolts to volts to drive the aircraft radio.

Jim




"Richard Riley" > wrote in message
...
> On Mon, 02 Oct 2006 02:33:18 GMT, "Cy Galley" >
> wrote:
>
>>I believe Comtronics has a web site. Why not ask the maker?
>
> They want $120 for $15 worth of jacks and 3 feet of wire. They're
> free to charge that much - but I'm free to try making one on my own.
> So I'm going to give it a shot.

[[email protected]]

Richard

I used to use ex-military headsets and with a little experimentation I
designed an audio amplifier based on the BC108 transistor to do exactly
what RST are suggesting. There were a couple of capacitors and
resistors and a variable pot. The variable pot was the biggest item,
even though I used miniature versions. Unfortunately I am away from
home and I can't remember more, but maybe you have enough info now to
start your project. As I posted in a previous unrelated topic, low cost
replacement cables are available from Headsets Inc at $19
http://www.headsetsinc.com/price_list.htm . The transistor and
components will cost a few cents.

Stan


Richard Riley wrote:
> On Sun, 1 Oct 2006 21:34:47 -0700, "RST Engineering"
> > wrote:
>
> >That's because it ain't $120 worth of jacks and wire. It is $120 worth of
> >amplifier that takes those few millivolts of microphone audio, uses the bias
> >voltage coming down the aircraft radio mic audio line, smooths that voltage
> >into a working voltage for an amplifier, and provides an amplifier that
> >takes those millivolts to volts to drive the aircraft radio.
> >
>
> But I can plug my ordinary David Clark headsets into the dull old Icom
> (handheld) standard patch cable and they work fine. Is the
> Comtronics mic totally different from the David Clark mic?

[Jim Logajan]

"RST Engineering" > wrote:
> That's because it ain't $120 worth of jacks and wire. It is $120
> worth of amplifier that takes those few millivolts of microphone
> audio, uses the bias voltage coming down the aircraft radio mic audio
> line, smooths that voltage into a working voltage for an amplifier,
> and provides an amplifier that takes those millivolts to volts to
> drive the aircraft radio.

I suspect the decimal point needs adjusting - I would have expected a
cost on the order of $12 rather than $120. Jameco carries a number of
educational audio kits that give an idea of the cost of the underlying
hardware needed to perform the task.[1] But unless one is comfortable
with electronics and one has more time than money, presumably the
simplest option is to buy the $120 system.

[1] http://www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=703005

[RST Engineering]

"Richard Riley" > wrote in message
...
> On Sun, 1 Oct 2006 21:34:47 -0700, "RST Engineering"
> > wrote:
>
>>That's because it ain't $120 worth of jacks and wire. It is $120 worth of
>>amplifier that takes those few millivolts of microphone audio, uses the
>>bias
>>voltage coming down the aircraft radio mic audio line, smooths that
>>voltage
>>into a working voltage for an amplifier, and provides an amplifier that
>>takes those millivolts to volts to drive the aircraft radio.
>>
>
> But I can plug my ordinary David Clark headsets into the dull old Icom
> (handheld) standard patch cable and they work fine. Is the
> Comtronics mic totally different from the David Clark mic?

No, the microphones themselves are electrically similar. THe difference is
that the Clark headsets have the amplifier cleverly hidden (usually in one
earcup) that takes the millivolts of the actual microphone element and makes
the volts necessary to drive the aircraft radio.

The whole problem is that civilian aircraft microphones have to simulate an
old wheezy carbon element, while military microphones are the raw dynamic or
electret elements without any matching electronics.

Jim

[RST Engineering]

I didn't say anything about the actual parts cost, just the price of the
product. Can you make it for nickels and dimes of parts? You bet. Can you
sell it for $120? Obviously.

Old story about the retired A&P who was called in to see if he could find
the problem with a 747 that nobody else could find. Ten minutes later he
marks a part with an X in chalk and says replace this part and the problem
will be fixed. SUre as hell, they replaced the part and the problem was
fixed. A&P sends the airline a bill for $10,000. The airline objects that
it took ten minutes to find the problem and the bill is excessive and please
itemize. THey got the bill back with $100 for marking the part and $9,900
for knowing where to mark. They paid.

Jim



"Jim Logajan" > wrote in message
.. .

>
> I suspect the decimal point needs adjusting - I would have expected a
> cost on the order of $12 rather than $120.

[john smith]

In article >,
"RST Engineering" > wrote:

> I didn't say anything about the actual parts cost, just the price of the
> product. Can you make it for nickels and dimes of parts? You bet. Can you
> sell it for $120? Obviously.
>
> Old story about the retired A&P who was called in to see if he could find
> the problem with a 747 that nobody else could find. Ten minutes later he
> marks a part with an X in chalk and says replace this part and the problem
> will be fixed. SUre as hell, they replaced the part and the problem was
> fixed. A&P sends the airline a bill for $10,000. The airline objects that
> it took ten minutes to find the problem and the bill is excessive and please
> itemize. THey got the bill back with $100 for marking the part and $9,900
> for knowing where to mark. They paid.

Old engineering joke, many variations.
Here is another one for you.
Jim, do you know the measure of 1 ORCH?

[RST Engineering]

I know how to measure in the RCH system, but never heard of an ORCH. A
variation on the theme, no doubt.

Have you ever heard of measuring feminine pulchritude in millihelens?

Jim

>
> Old engineering joke, many variations.
> Here is another one for you.
> Jim, do you know the measure of 1 ORCH?

[john smith]

In article >,
"RST Engineering" > wrote:

> I know how to measure in the RCH system, but never heard of an ORCH. A
> variation on the theme, no doubt.

> Have you ever heard of measuring feminine pulchritude in millihelens?

Sorry, the O and 1 are redundant.
No, I am not familiar with millhelens.

[kd5sak]

"john smith" > wrote in message
...
> In article >,
> "RST Engineering" > wrote:
>
>> I know how to measure in the RCH system, but never heard of an ORCH. A
>> variation on the theme, no doubt.
>
>> Have you ever heard of measuring feminine pulchritude in millihelens?
>
> Sorry, the O and 1 are redundant.
> No, I am not familiar with millhelens.


If I've got it "figgered" correctly the original Helen ("Paris Downfall")
would have been rated at
1000 millihelens, Marjorie main would have come in at about 75 millihelens
and Kim Novak at about 1390 millihelens. To bring it into the modern era,
Paris Hilton might rate as high as 395
millihelens. I think I've got the concept straight but we might differ on
the calibration.

Harold
KD5SAK

[Montblack[_1_]]

("Richard Riley" wrote)
> The original Helen was One Helen. 1H=1000 ships, 1 mH=1 ship.
>
> So at a guess, Kim Novak might be 3-5 mH. Condi Rice, all things
> considered, could rate perhaps 200 mH in todays world.
>
> Paris Hilton is on the RC scale (see: The Ransom of Red Chief)


I thought RC scale meant 'Redundant Celebrity' as in: "Famous for being
Famous"

<puke>.


Montblack ...So, who floats my boat? :-)

Raquel Welch - duh!

Seven of Nine
1 Starship = (1,000 Greek ships) x (1,000)...

Charlize Theron (5'11")
<http://www.the-movie-times.com/thrsdir/actress/gallery/gallery.mv?ctheron+10>

Minnie Driver
http://minniedriver.net/photos/index.htm

etc, etc, etc, etc, etc, etc...

From: Dumb & Dumber (1994)

Lloyd: What are the chances of a guy like you and a girl like me... ending
up together?
Mary: Well, that's pretty difficult to say.

Lloyd: Hit me with it! I've come a long way to see you, Mary. The least you
can do is level with me. What are my chances?

Mary: Not good.
Lloyd: You mean, not good like one out of a hundred?

Mary: I'd say more like one out of a million.
[pause]
Lloyd: So you're telling me there's a chance.