Today's Message Index:
----------------------
1. 12:00 PM - Re: Intercom question (jrevens)
2. 02:09 PM - Re: Re: Intercom question (Robert L. Nuckolls, III)
3. 05:08 PM - Re: Power Generation without Battery (jrevens)
4. 07:12 PM - Re: Re: Power Generation without Battery (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Intercom question |
nuckolls.bob(at)aeroelect wrote:
> At 23:14 2015-02-06, you wrote:
>
> >
> > Thanks, Bob. It looks like they are going to use aviation headsets... probably
donated units of various brands. Not everyone has to necessarily be able
to "transmit" (push-to-talk) to the other headsets - perhaps only 1 or 2 ("pilot"
& "co-pilot"), & everyone else able to hear at least. The mock-up is basically
of the nose section, so maximum distances of wire runs would be approximately
10 or 15 feet. The leaders of this project feel that it will add to the experience
if the kids can connect in this way. BTW, this project is written about
in the latest "Sport Aviation" magazine on p.110.
> >
> > --------
> > John Evens
>
>
> Understand. My recommendation is to start with
> any sort of pre-packaged audio amplifier. One
> like this would work nicely.
>
> [img]cid:.0[/img]
>
> There are dozens of similar devices on eBay. I've
> used a bunch in various applications with good
> results and value. You can power them up with a
> 12v 'wall wart'. In fact, if you'll shoot me an
> address, I donate an amplifier and power supply
> to the project.
>
> The next thing you need to do is cobble up the
> interface that makes an aircraft microphone 'look'
> like something found in the rest of the world . . .
>
> [img]cid:.1[/img]
>
> A circuit like that shown above will allow
> you to bias-up and mix as many microphones
> together as needed. PTT for any particular
> mic can be a simple n.c. push button in parallel
> with the microphone. The button shorts out the
> mic unless being used. This is preferable to
> putting a n.o. button in series . . . the
> parallel configuration reduces the DC level
> shift and resulting 'pop' you hear in the system
> as any one microphone is keyed.
>
> Headphones can simply be paralleled assuming
> they're all about the same efficiency where volume
> can be managed by the single control on the amplifier.
> Recommended circuitry not shown is a 220 ohm, 1/2
> watt resistor in series with each line out to
> a headset. At worst, you may have to balance
> relative audio levels in the headsets which
> can be accomplished by adjusting the value of that
> 220 ohm resistor.
>
> Got somebody in your group that's handy
> slinging solder?
>
>
>
>
> Bob . . .
Thank you so much, Bob! That's exactly what I was hoping for.
I'm sure I can handle building the mic mixing circuit. If I used an
adjustable 1/2 watt potentiometer to each headset, what value
would you recommend - 220 ohm, or higher? Probably a stupid
question, but what type capacitors should I use - electrolytic, or?
I would gratefully accept your offer of an amp & power supply...
I will send you an email. Again, from myself, our chapter, and
the Young Aviators - thank you!!
--------
John Evens
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=438170#438170
Message 2
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| Subject: | Re: Intercom question |
>Thank you so much, Bob! That's exactly what I was hoping for.
>I'm sure I can handle building the mic mixing circuit. If I used an
>adjustable 1/2 watt potentiometer to each headset, what value
>would you recommend - 220 ohm, or higher? Probably a stupid
>question, but what type capacitors should I use - electrolytic, or?
>I would gratefully accept your offer of an amp & power supply...
>I will send you an email. Again, from myself, our chapter, and
>the Young Aviators - thank you!!
Got the mailing address. I dug out an amplifier
and power supply. Need to find my MP3 player to
test it for functionality.
What you might consider is a volume control
at each station where a headset is plugged in.
Set the master volume on the amplifier on
the 'generous' side and let each station
set their own volume to suit.
There's some other options to consider. If
some of the stations are listen-only, you
could use contemporary headsets (10-50
ohm) for a lot less money than aviation
headsets (100+ ohms). Each station's
volume control would be a 50-ohm,
wire wound potentiometer.
http://tinyurl.com/nqruvxd
The capacitors shown are all electrolytic.
Any time you see a "+" sign associated with
the symbol, that tells you that it's some
form of electrolytic. I've got all those
parts in my sand-box-bins. I'll include
a kit of loose parts with the amplifier.
Bob . . .
Message 3
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| Subject: | Re: Power Generation without Battery |
I'll be purchasing a Rotax 912ULS in the near future, and in following some of
the online forums there seems to be some confusion about the need & reason for
the recommended 22,000 uf 25v capacitor in the charging circuit, as shown also
in Bob's Z-16 diagram. I also read about the fairly common failure of the Rotax
supplied voltage regulator. So in doing a little research I've come across
the following replacement regulator made in Germany:
http://www.silent-hektik.com/UL_R_912.htm. (I'm not sure if this has been posted as a link or not... sorry). Anyway, if you run a translation program on this, the ad seems to be saying that the capacitor is there to allow the dynamo and regulator to work if the battery is disconnected.I don't think I've ever heard this before. I may be wrong. It also recommends a 33,000 uf 40v capacitor, saying the original recommended one is marginal in size. In the interest of furthering my knowledge, are there any comments about this? I apologize if this has already been discussed here, and if so, please do not archive.
--------
John Evens
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=438172#438172
Message 4
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| Subject: | Re: Power Generation without Battery |
At 19:06 2015-02-08, you wrote:
I'll be purchasing a Rotax 912ULS in the near future, and in
following some of the online forums there seems to be some confusion
about the need & reason for the recommended 22,000 uf 25v capacitor
in the charging circuit, as shown also in Bob's Z-16 diagram. I also
read about the fairly common failure of the Rotax supplied voltage
regulator. So in doing a little research I've come across the
following replacement regulator made in Germany:
http://www.silent-hektik.com/UL_R_912.htm. (I'm not sure if this has
been posted as a link or not... sorry). Anyway, if you run a
translation program on this, the ad seems to be saying that the
capacitor is there to allow the dynamo and regulator to work if the
battery is disconnected.I don't think I've ever heard this before. I
may be wrong. It also recommends a 33,000 uf 40v capacitor, saying
the original recommended one is marginal in size. In the interest of
furthering my knowledge, are there any comments about this? I
apologize if this has already been discussed here, and if so, please
do not archive.
I'll be researching both of these questions over the
next few weeks. I'm hoping to get into B&C's lab next
Tuesday to do some of preliminary tests.
We'll be investigating a number of regulators for
robustness and suitability to task. I'm amazed that
the legacy Ducati R/R offered with the 912/914
engine wasn't replaced or upgraded years ago. It
has always been marginal.
While I'm fiddling with R/R, I'll look at the
self-excitation and sans-battery characteristics
of these systems with and without a capacitor.
Bob . . .
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