---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 02/07/15: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:13 AM - Re: Re: Intercom question (Dan Brown) 2. 06:41 AM - Re: Re: Intercom question (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 04:13:37 AM PST US From: "Dan Brown" Subject: RE: AeroElectric-List: Re: Intercom question Just read the article ...very cool! -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of jrevens Sent: Saturday, February 07, 2015 12:15 AM Subject: AeroElectric-List: Re: Intercom question 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 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=438150#438150 ________________________________ Message 2 _____________________________________ Time: 06:41:08 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Intercom question 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. Emacs! 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 . . . Emacs! 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 . . . ------------------------------------------------------------------------------------- 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.