AeroElectric-List Digest Archive

Fri 04/06/07


Total Messages Posted: 5



Today's Message Index:
----------------------
 
     1. 05:12 AM - Re: aux music input quiet on flightcom 403mc (Robert L. Nuckolls, III)
     2. 07:09 AM - Re: Electrical Design Confusion (Greg Vouga)
     3. 08:03 AM - Re: aux music input quiet on flightcom 403mc (Ron Quillin)
     4. 07:12 PM - Re: aux music input quiet on flightcom 403mc (bryanflood)
     5. 07:21 PM - Re: aux music input quiet on flightcom 403mc (bryanflood)
 
 
 


Message 1


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    Time: 05:12:39 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: aux music input quiet on flightcom 403mc
    At 09:05 PM 4/5/2007 -0700, you wrote: > >I had the same problem many others did connecting a music input to my >flightcom 403mc. The music was so soft at top volume I could barely hear >it on the ground and not at all in flight. Turns out in order to save $ >there is apparently no pre-amp in this intercom. So if you want to hook up >an mp3 player or walkman or whatever you need to supply your own pre-amp. >I looked at all the options and decided to try to build my own. I looked >at a lot of circuits and borrowed heavily from some like Bob N. I had >problems with bobs circuit when coverting from a stereo input to a mono >output. It appears that on his amp design where one leg of the stereo >input goes to the + input on the op amp and the other leg of the stereo >input to the - input on the op amp. So when you hook it up it seems some >of the music cancels out any you get some really funky sounds. Very cool, >but no music. Maybe I did it wrong, after all Bob is the expert but it >certainly looked like bobs design on the breadboar! > d. After lots of testing however I made changes to any existing designs > to get the volume to a reasonable level in the headset with the volume > control turned to a medium level on my mp3 player. My set-up is simple > the mp3 player headphone jack simply goes into the aux music input jack > which goes thru this little amp and then to the intercom. Anyway, I'm not > an electrical engineer (I'm mechanical) so I am really not all that great > at designing circuits, but this one works for me. I thought I would post > it in case anybody want to use it as a starting point for their own amp. > >http://www.geocities.com/bryanflood2001/AudioAmpfor403MC.bmp You might want to consider a couple of resistors in series with each of the stereo outputs before you bring them together as a monophonic mix. Output signals from the two channels are not identical and some degradation of audio will occur when the outputs "load" each other as described in the chapter on audio systems. Something on the order of 47 ohms per side is suggested. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 2


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    Time: 07:09:53 AM PST US
    From: "Greg Vouga" <gmvouga@hotmail.com>
    Subject: Re: Electrical Design Confusion
    Bob, Thanks for your input. Looks like Z-13/8 is the direction that I'll be going. Greg >From: "Robert L. Nuckolls, III" <nuckollsr@cox.net> >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: Electrical Design Confusion >Date: Thu, 05 Apr 2007 20:20:38 -0500 > ><nuckollsr@cox.net> > >At 09:24 AM 4/5/2007 -0700, you wrote: > >><gmvouga@hotmail.com> >> >>Bob, >> >>Thanks for the information. This is helping... However, i have a couple >>more questions. >> >>1. The LR-3 alternator controller looks like a nice option and simplifies >>things (crowbar, indicator light, regulator all-in-one) for the main >>alternator. Is there any reason, other than cost, not to use this? > > The voltage regulator for an SD-8 is unique to that product and comes > with it. You can't use an LR-3 with the SD-8. > > >>2. For the SD-8 it would be nice to have a indicator light or gage to >>make sure it's functioning properly. I could wire this into the circuit >>as well, but I still need regulator and crowbar OV. So... Is there any >>reason not to use the LR-3 other than cost. In Z-13/8 it simply states >>"voltage Regulator." Is there a specific model that you recommend? > > The functionality indicator for ALL alternators is active > notification of low volage . . . i.e. flash a light > if the bus voltage is less than 13.0 volts. OV protection > for the SD-8 is illustrated in Z-13/8 > > >>As you might already be able to figure out, I'm a little electron >>challenged. So forgive me if any of these questions seem a somewhat >>basic. >>I have actually read the AeroElectric Connection, but I'm still a little >>confused. I'm really just looking for a safe, simple, wiring archetecture >>that will fit my equipment (Avionics and engine) choices. Saving a few >>pennies would be nice, but at this point i would pay a few more bucks to >>make it simple. The This is really the reason that I was thinking of just >>trading the SD-8 for the 20 amp alternator in Z-13/20. I don't think I >>need the 20A alternator, and the SD-8 will add the safety that I am >>looking for in my all electric system. Is there any reason not to do >>this? > > Yes. Too heavy, too expensive and overkill for what you need. > Z-13/8 as published is all you're going to ever need and > more. > > Bob . . . > > _________________________________________________________________ Interest Rates Fall Again! $430,000 Mortgage for $1,399/mo - Calculate new payment


    Message 3


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    Time: 08:03:59 AM PST US
    From: "Ron Quillin" <rjquillin@gmail.com>
    Subject: Re: aux music input quiet on flightcom 403mc
    A couple of comments if I may. First I have to agree with Bob, directly connecting two outputs to one another is not a good idea, at all, and can cause damage to the output circuit of the source device. 47 ohms would work, but at a minimum use a value equal to the impedance (resistance) of the earphone/speaker normally connected; say 10 ohms minimum. Also, the 10 ohm 10uF combination will limit low frequencies below ~1600Hz; Ok if you don't want much low end, but... Attached is a pdf you may want to try. Keep the rest as you had it if it seems to work well. This one will sum (mix) the L & R signals without nuking the mp3 player's output, should give you cleaner audio as well. If you don't like the 10/100 ohm pair, go to 100/1k instead. Also with this combination the LF will be extended down to about 160Hz. Ron Q. old audio engineer. > > <snai> Anyway, I'm not > > an electrical engineer (I'm mechanical) so I am really not all that great > > at designing circuits, but this one works for me. I thought I would post > > it in case anybody want to use it as a starting point for their own amp. > > > >http://www.geocities.com/bryanflood2001/AudioAmpfor403MC.bmp > > You might want to consider a couple of resistors in > series with each of the stereo outputs before you > bring them together as a monophonic mix. Output > signals from the two channels are not identical > and some degradation of audio will occur when the > outputs "load" each other as described in the chapter > on audio systems. Something on the order of 47 ohms > per side is suggested. > > Bob . . .


    Message 4


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    Time: 07:12:24 PM PST US
    Subject: Re: aux music input quiet on flightcom 403mc
    From: "bryanflood" <bryanflood@hotmail.com>
    Bob and Ron, thanks for the advice, it looks like I may need to do yet another mod... for some reason I am having trouble with the .pdf file from Ron. Could you send it to me directly at bryanflood@hotmail.com? I would really appreciate it. Thanks again, Bryan -------- Rv-9A completed. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=105395#105395


    Message 5


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    Time: 07:21:19 PM PST US
    Subject: Re: aux music input quiet on flightcom 403mc
    From: "bryanflood" <bryanflood@hotmail.com>
    WOOPS, I foud the drawing from Ron. Just needed to read a bit further. Sorry, Bryan -------- Rv-9A completed. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=105398#105398




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