---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 02/08/15: 4 ---------------------------------------------------------- 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 _____________________________________ Time: 12:00:38 PM PST US Subject: AeroElectric-List: Re: Intercom question From: "jrevens" 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 _____________________________________ Time: 02:09:50 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 05:08:57 PM PST US Subject: AeroElectric-List: Re: Power Generation without Battery From: "jrevens" 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 _____________________________________ Time: 07:12:23 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.