---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 11/30/10: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 0. 12:52 AM - [Please Read] - Last Official Day of List Fund Raiser! (Matt Dralle) 1. 02:58 AM - Re: Radio noise (b d) 2. 07:43 AM - Re: iPod audio mix into headset line (James Robinson) 3. 07:53 AM - Re: Radio noise (Robert L. Nuckolls, III) 4. 10:25 AM - Re: Radio noise (Robert L. Nuckolls, III) 5. 10:42 AM - Re: iPod audio mix into headset line (Fisher Paul A.) 6. 11:18 AM - Re: iPod audio mix into headset line (Tim Olson) 7. 01:36 PM - Headphone impedance (Peter Pengilly) 8. 04:57 PM - Re: Radio noise (b d) 9. 05:12 PM - Re: Radio noise (Robert L. Nuckolls, III) 10. 06:21 PM - Re: Radio noise (Noel Loveys) 11. 06:46 PM - Re: Headphone impedance (Noel Loveys) 12. 07:06 PM - Re: Vans RPM Transducer IE VTACHGEN 12 (PhilCobbin) 13. 10:49 PM - Re: Headphone impedance (Ron Quillin) ________________________________ Message 0 _____________________________________ Time: 12:52:51 AM PST US From: Matt Dralle Subject: AeroElectric-List: [Please Read] - Last Official Day of List Fund Raiser! Dear Listers, Its November 30th and that means at least two things. For better or worse, its my 47th birthday! But it also means that its that last official day of the Matronics Email List Fund Raiser! If you been drooling over one of the really nice gifts that are available this year with a qualifying Contribution, then now is the time to jump on one!! If you've been meaning to make a Contribution this month but have been putting it off for some reason, NOW is the time! I will be posting the List of Contributors in a few days, so you'll probably want to be known as a person that supported the Lists! I want to thank everyone that has so generously made a Contribution this year in support of our Lists. It is your generosity that keeps this operation running and I don't ever forget it. Hopefully everyone feels the same. The List Contribution Web Site is fast and easy. Please support our habit by making your Contribution right now: http://www.matronics.com/contribution Or, by dropping a personal check in the mail to: Matt Dralle / Matronics 581 Jeannie Way Livermore CA 94550 Thank you to all in advance! Matt Dralle Matronics Email List Administrator ________________________________ Message 1 _____________________________________ Time: 02:58:23 AM PST US Subject: Re: AeroElectric-List: Radio noise From: b d *Ron,* ** *I'd say you agree with me, right Ron? I typically like to leave some wiggle room for interpretation so I phrased my observation as a question as opposed to a fact. Some people explain "parallel and series" circuits differently than you and I do. You and I see and explain them the same the correct way. I'm not trying to be petty or split hairs because it really doesn't matter, I'm only pointing out that I did address the "parallel and series" issue earlier. See below.* ** *Best regards, Bruce* On Mon, Nov 29, 2010 at 6:04 PM, Ron Quillin wrote: > At 08:47 11/29/2010, you wrote: > > Saw a wiring diagram for another radio which stated that you must install a > 22,000uf capacitor in series on the 12v feed when used with the Rotax engine > installation. > > > As no one else commented on what seems to be a typo or misunderstanding of > terms... > That capacitor would be parallel; that is the positive terminal to your > buss, and the negative terminal to airframe or whatever you are using for a > "ground". > *Bruce:* *"In series or in parallel? Series doesn't sound right but then I don't know if you are saying what I think you are saying. Series would not allow any current to flow on a DC circuit hense the radio would not work. Parallel would essentially filter out the unwanted noise sending it to ground." (previous post) * > > For a component to be in "series", the load current would flow through the > component in series; clearly for DC and a capacitor, this would not work. > Were it a coil, inductor, series would be the proper configuration. > > Ron Q. > > > * > > ________________________________ Message 2 _____________________________________ Time: 07:43:00 AM PST US From: James Robinson Subject: Re: AeroElectric-List: iPod audio mix into headset line Hi Tim That is very interesting. I have been very happy with the Zulu's but I have not done a direct comparison with the Bose. The Glasair without upholstery is very noisy and the Zulu seem to work great, but I need to borrow someones Bose and do a direct comparison. Good luck in your quest. Jim James Robinson Glasair lll N79R Spanish Fork UT U77 ________________________________ From: Tim Olson Sent: Mon, November 29, 2010 9:39:10 PM Subject: Re: AeroElectric-List: iPod audio mix into headset line Actually, that's the sad thing. I have 5 Bose X's, and ordered two Bose A20's to get the music input (wired only). Then I decided that even though I know I love the Bose best, I better re-visit Lightspeed Zulu's. These are for the kids, BTW, so small heads for sure. Even myself, I wear them at their smallest setting, since I'm a pea-brained guy. Anyway, we had the kids try the Zulu's on. They were too big. But, then I heard about the thicker head pad, and got one on the way. I ordered a Zulu, and got it last week. This weekend I got out for a test flight. That's where my plans all fell apart. Up to that point, I was happy to just buy 2 pairs of Zulu's for the kids, and be done with it. The problem is, when I compared the Zulu's to my Bose X's, which are supposed to be inferior to the A20's, I was very very disappointed. The Zulu's were AWESOME for music via bluetooth. I was thrilled with that. But, on the ground I noticed one thing...the audio is higher pitched more "tinny" on the Zulu's. Then, the real disturbing thing...the in-flight test. On ground taxi, the cabin noise was much louder, both the low rumble, and the higher pitched rattles. In climbout, the Zulu's were far noisier...in all respects. So much so that the audio music took more volume just to hear it well. (that said, the bluetooth volume can be made nice and loud) But, they were very loud. In cruse...same thing. The zulu's just didn't hold a candle to my Bose X's. I was super upset, because I was hoping that the Zulu's would dig me out of having to do all this work. If Bose would have only come out with A2DP streaming music input in the A20's I'd buy it in a heartbeat, but man, what a stupid mistake they made by not doing it...a dedicated guy with 5 pairs who'd gladly buy 2 more, and they don't actually make a product that can compete in features? The fit and clamping pressure is great with the Zulu's, and I can get a bit better noise reduction if I hold the earcups tightly on my head, but even if I ordered their thicker earpads, that's not really a solution...even with them held tight, they still weren't as quiet. In fact, my wife thought the difference was so stark she told me "OH, did you forget to power them on?!?!", and sadly, I hadn't forgotten. So yeah, the Zulu's would be a great solution, but having actually ran them head-to-head, I can't sacrifice that much on noise reduction and be happy. Even passive noise reduction wasn't really much different than the X's. I got the impression that when you read magazine reviews on these headsets that it's either VERY VERY VERY perfect fit oriented, or that the reviewers don't want to lose advertising revenue, because I really didn't find them to be nearly as equal as all the reviews would indicate. I may call them tomorrow to see if there is anything that can be tweaked to fix it. Had they fit like Bose, and sounded like Bose, I'd have bought another pair in a heartbeat and I wouldn't be asking for this circuit. Tim Olson - RV-10 N104CD do not archive On 11/29/2010 9:58 PM, James Robinson wrote: > Hi Tim > it is to bad you didn't go with Lightspeed. They allow a IPod directly > into the controler or by bluetooth I think. I plug my ipod nano directly > into mine and it works great. > > Jim > James Robinson > Glasair lll N79R > Spanish Fork UT U77 > > > ------------------------------------------------------------------------ > *From:* Tim Olson > *To:* aeroelectric-list@matronics.com > *Sent:* Mon, November 29, 2010 8:28:58 PM > *Subject:* AeroElectric-List: iPod audio mix into headset line > > > > > I thought I'd ask for a bit of help on this mini-project I > am going to try to tackle. > > My goal is to be able to take my standard Bose X headsets, > and splice in at jack point in the rear seats, so that I > can mix an ipod audio signal into the headset audio. Sounds > pretty simple, but... > > With the impedance mismatch between the ipod (I think 32 or > 36 ohms) and the headset (what is it, 300?) you would get only > quiet audio. I checked by plugging the headset with an > adapter directly into the ipod and it just was too quiet. > > I did a little digging into simple mixer circuits with > 10K resistors only, to combine the audio, and I'm guessing > that would work, if the ipod was just amp'd up a bit. > > One thing I am NOT concerned with, is auto-muting of > music, or anything like that. This is for rear-seat > only, for the kids. I want them to each be able > to plug in their ipod into an armrest jack, and hear > their own individual music in the headset. Right now, > they can plug into the intercom's input #2, and get the > SAME music, but I want them to have the option to > get DIFFERENT music than the other. I do want it to be > Stereo, too. > > So what I really am thinking I need to come up with is a > simple amp/mixer circuit that would perhaps impedance > match, or perhaps just amplify the ipod audio and then > mix it in. > > To make it even more fun, once I get far enough that > I know this works, I'm going to plug a bluetooth > audio interface into that jack, and that way they can > just pair their ipod touch with the bluetooth module > and go wire-free. > > So does anyone have any good advice on the circuit to > accomplish this? FWIW, I'd be > > * > > * ________________________________ Message 3 _____________________________________ Time: 07:53:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Radio noise Saw a wiring diagram for another radio which stated that you must install a 22,000uf capacitor in series on the 12v feed when used with the Rotax engine installation. Ron correctly replies: As no one else commented on what seems to be a typo or misunderstanding of terms... That capacitor would be parallel; that is the positive terminal to your buss, and the negative terminal to airframe or whatever you are using for a "ground". For a component to be in "series", the load current would flow through the component in series; clearly for DC and a capacitor, this would not work. Were it a coil, inductor, series would be the proper configuration. Ron Q. Some people explain "parallel and series" circuits differently than you . . . May I suggest that differences in explanation have more to do with illuminating the speaker's understanding than it does with debating the value of various 'interpretations'? I'll refer the debaters to the Z-figures were there are numerous examples of how the subject capacitor is wired. I'll also cite every text I've ever picked up wherein Ohms law, reactance, and measurement of currents and voltages are explained in uniform and explicit illustrations for series and parallel connections. An exemplar figure from the texts I used at Great Lakes Naval Training Schools: Emacs! This goes to the value of common understanding of the words used in language. Without common understanding the useful exchange of ideas and knowledge cannot take place. Bob . . . ________________________________ Message 4 _____________________________________ Time: 10:25:56 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Radio noise ---------------- On Mon, Nov 29, 2010 at 8:47 AM, Philip Smith wrote: I know this has been discussed before but like to ask anyway. I installed an old RST 360 com radio in my 701 panel and when I start the "Rotax" it is very noisy. Seems to be a whine don't know whether or not this is alternator or ignition. Saw a wiring diagram for another radio which stated that you must install a 22,000uf capacitor in series on the 12v feed when used with the Rotax engine installation. Will this cure the problem? Your valued thoughts please. ---------------- At 11:17 AM 11/29/2010, you wrote: G`morning Phil I am having a similar problem with my Kitfox Vixen with a 912UL. My radio is a new ICOM A210. I have installed one capacitor on the output from the voltage regulator. This helped but the problem still there but not where I would like it. None of my wiring is shielded and I am wondering if this would help. Shielding of wires never fixes a "whine". By whine, I presume you're describing a sort of musical pitch noise. Further, if it rises and falls in pitch with engine RPM, it's almost certainly CONDUCTED noise from the alternator coming in on the +14V bus -OR- or is being injected to a signal or power pathway due to poor grounding practice. Here's the problem with attempts to remotely diagnose and/or suggest prophylactic measures. The combinations of engine, radios, and intercoms being discussed have been installed many, many times before with no reported problems. From this admittedly anecdotal observation I deduce that something in the problem-systems is DIFFERENT than for the historical fleet of similar systems. The 'street-wise' suggestions for fixing the symptoms will include a sprinkling of materials and processes known to have some beneficial effects on some noise problem on some system at some point in history. But as described in the chapter on noise, every noise problem has a (1) victim (obviously), (2) a propagation pathway and a (3) source. Deducing the noise-trinity is a lot like playing the board game Clue. In the cases before us now, we know (1) and (3). The task is to deduce (2). Techniques for filling in (2)____________ blank are described in the chapter on noise. Alternatively, one can ponder a constellation of hypotheticals with some assurance that EVENTUALLY the noise can be run to ground or at least reduced to tolerable levels. Bob . . . ________________________________ Message 5 _____________________________________ Time: 10:42:17 AM PST US From: "Fisher Paul A." Subject: RE: AeroElectric-List: iPod audio mix into headset line Tim, Is this what you are looking for? http://www.vx-aviation.com/page_2.html I know you asked for a circuit, but I remember seeing these in the past. Never used one though... - Paul -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Tim Olson Sent: Tuesday, November 30, 2010 00:30 Subject: Re: AeroElectric-List: iPod audio mix into headset line ...snip... ________________________________ Message 6 _____________________________________ Time: 11:18:33 AM PST US From: Tim Olson Subject: Re: AeroElectric-List: iPod audio mix into headset line Thanks Paul, I did run across that last night. Almost emailed for more info. My first thought is, it's probably MORE than I need. I don't need Cell input, and I can't tell from some of the descriptions on other models if it can mix Stereo to my Stereo intercom, or only mix stereo into Mono. With all of the features it may be just a little higher on price than I'm looking for, although if it worked perfectly and was clear to me how it would work for my installation, and be airplane powered, I'd probably consider it. Right now, with the lack of any D-I-Y circuits that look ideal, I'm considering this Boostaroo Revolution: http://www.boostaroo.com/store_detail.php4?id=114 which I at least know I can just power via 12V, so it would amp the iPod signal easily. Then, I can do a simple resistor-only circuit to mix the audio to the headset audio. I did order a couple of isolator cords from Crutchfield too, to prevent ground loops and make headset whine. So, I'm at the point where I know I can do the bare minimum for about $60, or do Bluetooth with all that for about $140 per seat in the rear. I need one of my Bluetooth things to come in so I can verify if I need an amp first. Tim Olson - RV-10 N104CD do not archive On 11/30/2010 12:37 PM, Fisher Paul A. wrote: > --> AeroElectric-List message posted by: "Fisher Paul A." > > Tim, > Is this what you are looking for? http://www.vx-aviation.com/page_2.html > > I know you asked for a circuit, but I remember seeing these in the past. Never used one though... > > - Paul > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Tim Olson > Sent: Tuesday, November 30, 2010 00:30 > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: iPod audio mix into headset line > > --> AeroElectric-List message posted by: Tim Olson > > ...snip... > ________________________________ Message 7 _____________________________________ Time: 01:36:42 PM PST US From: Peter Pengilly Subject: AeroElectric-List: Headphone impedance Hi, I have a question concerning headset impedance, and what will work. I am trying to build a helmet for use in an aerobatic airplane, the principal requirement is to be as thin as possible on top of my head. I have found a parachuting helmet that seems ideal - and is very comfortable. Now I want to add comms. I was going to use a Halo headset, but its a problem sticking the ear plugs in your ears before putting the helmet on. At the weekend I was at a motorcycle show and was talking with an intercom maker. He sold me a kit to add comms to a motorcycle helmet, including an electret boom mic and a pair of thin speakers that fix inside the helmet. He didn't know the impedance of the speakers, but suspects they are quite low. I said I needed 600 ohms - his reply was that it wouldn't be a problem. The audio system is quite simple - Becker AR4201 straight to the headset. The Becker manual says: Receiver data ... Rated output: for speaker operation: at 13.75 V nominal operating voltage >= 3 W at 4 ohms at 10.0 V operating voltage (emergency mode) >= 1.5 W at 4 ohms with headset connected: at 13.75 V nominal operating voltage >= 100 mW at 600 ohms at 10.0 V operating voltage (emergency mode) >= 30 mW at 600 ohms So the question is, how are these speakers that I am about to stick into my helmet going to react when the radio output is fed to them? If their impedance is low I'm guessing that will impact the volume, so I imagine I will have to turn the radio volume up? It a noisy airplane and is already up fairly high. Can I add some resistors to help out? Do I connect both speakers to the tels output (doesn't that cut the already low impedance in half?) Are all electret mics the same? Thanks, Peter ________________________________ Message 8 _____________________________________ Time: 04:57:21 PM PST US Subject: Re: AeroElectric-List: Radio noise From: b d Okay, whatever! LOL *"May I suggest that differences in explanation have* * more to do with illuminating the speaker's understanding than it does with debating the value of various 'interpretations'? I'll refer the debaters to the Z-figures were there are numerous examples of how the subject capacitor is wired. I'll also cite every text I've ever picked up wherein Ohms law, reactance, and measurement of currents and voltages are explained in uniform and explicit illustrations for series and parallel connections. An exemplar figure from the texts I used at Great Lakes Naval Training Schools: This goes to the value of common understanding of the words used in language. Without common understanding **the useful exchange of ideas and knowledge cannot take place. * * **Bob . . ."* ________________________________ Message 9 _____________________________________ Time: 05:12:06 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Radio noise At 06:51 PM 11/30/2010, you wrote: >Okay, whatever! LOL Read that wrong. My apologies . . . Bob . . . ________________________________ Message 10 ____________________________________ Time: 06:21:10 PM PST US From: "Noel Loveys" Subject: RE: AeroElectric-List: Radio noise Bob: I feel a bit like I must have early onset Alzheimer's. I should have noticed that the description was to wire the capacitor in series on a DC circuit. As I'm sure you know but others may not, capacitors block DC and pass AC. So if you have a problem with noise on a DC feed simply put a capacitor from that line to ground and any noise (AC) on that line should be shunted to ground assuming the capacitor is of adequate size. Noel From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: November 30, 2010 12:20 PM Subject: Re: AeroElectric-List: Radio noise Saw a wiring diagram for another radio which stated that you must install a 22,000uf capacitor in series on the 12v feed when used with the Rotax engine installation. Ron correctly replies: As no one else commented on what seems to be a typo or misunderstanding of terms... That capacitor would be parallel; that is the positive terminal to your buss, and the negative terminal to airframe or whatever you are using for a "ground". For a component to be in "series", the load current would flow through the component in series; clearly for DC and a capacitor, this would not work. Were it a coil, inductor, series would be the proper configuration. Ron Q. Some people explain "parallel and series" circuits differently than you . . . May I suggest that differences in explanation have more to do with illuminating the speaker's understanding than it does with debating the value of various 'interpretations'? I'll refer the debaters to the Z-figures were there are numerous examples of how the subject capacitor is wired. I'll also cite every text I've ever picked up wherein Ohms law, reactance, and measurement of currents and voltages are explained in uniform and explicit illustrations for series and parallel connections. An exemplar figure from the texts I used at Great Lakes Naval Training Schools: Emacs! This goes to the value of common understanding of the words used in language. Without common understanding the useful exchange of ideas and knowledge cannot take place. Bob . . . ________________________________ Message 11 ____________________________________ Time: 06:46:35 PM PST US From: "Noel Loveys" Subject: RE: AeroElectric-List: Headphone impedance Looks to me your receiver requires a 4 ohm impedance. BTW you have to be careful not to confuse impedance with resistance even though they are related. Most low impedance headphones are 4 Ohms but check it should be written on the phones somewhere. A mismatch of impedance can result in poor clarity and in some instances problems with the audio output transistors of the radio. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Peter Pengilly Sent: November 30, 2010 6:01 PM Subject: AeroElectric-List: Headphone impedance Hi, I have a question concerning headset impedance, and what will work. I am trying to build a helmet for use in an aerobatic airplane, the principal requirement is to be as thin as possible on top of my head. I have found a parachuting helmet that seems ideal - and is very comfortable. Now I want to add comms. I was going to use a Halo headset, but its a problem sticking the ear plugs in your ears before putting the helmet on. At the weekend I was at a motorcycle show and was talking with an intercom maker. He sold me a kit to add comms to a motorcycle helmet, including an electret boom mic and a pair of thin speakers that fix inside the helmet. He didn't know the impedance of the speakers, but suspects they are quite low. I said I needed 600 ohms - his reply was that it wouldn't be a problem. The audio system is quite simple - Becker AR4201 straight to the headset. The Becker manual says: Receiver data ... Rated output: for speaker operation: at 13.75 V nominal operating voltage >= 3 W at 4 ohms at 10.0 V operating voltage (emergency mode) >= 1.5 W at 4 ohms with headset connected: at 13.75 V nominal operating voltage >= 100 mW at 600 ohms at 10.0 V operating voltage (emergency mode) >= 30 mW at 600 ohms So the question is, how are these speakers that I am about to stick into my helmet going to react when the radio output is fed to them? If their impedance is low I'm guessing that will impact the volume, so I imagine I will have to turn the radio volume up? It a noisy airplane and is already up fairly high. Can I add some resistors to help out? Do I connect both speakers to the tels output (doesn't that cut the already low impedance in half?) Are all electret mics the same? Thanks, Peter ________________________________ Message 12 ____________________________________ Time: 07:06:33 PM PST US Subject: AeroElectric-List: Re: Vans RPM Transducer IE VTACHGEN 12 From: "PhilCobbin" If you search around the Van's website there are installation notes on the various guages they sell and a drawing showing how they are typically wired. If you put say, 5 volts (instead of 12v) and slowly rotate the spindle on the sensor you will see it generate 8 steps of 4.26 volts. If you hook it up to 12 volts, you'll get comparable results. Since the sensor is typically attached to the camshaft, there are 4 steps from the unit per crankshaft revolution. attached is a jpeg of a digital tach setup I'm breadboarding for my rv7 using the little Italian arduino boards. The van's gauge if you take it apart and peruse the circuit board you will find it uses a frequency to voltage chip to drive the guage. Sorry about the size of the jpeg... Phil Read this topic online here: http://forums.matronics.com/viewtopic.php?p=321873#321873 Attachments: http://forums.matronics.com//files/2010_11_30_rv7_dig_tach_02s_145.jpg ________________________________ Message 13 ____________________________________ Time: 10:49:54 PM PST US From: Ron Quillin Subject: Re: AeroElectric-List: Headphone impedance At 13:31 11/30/2010, you wrote: > > >Hi, > >I have a question concerning headset impedance, and what will work. >I am trying to build a helmet for use in an aerobatic airplane, the >principal requirement is to be as thin as possible on top of my >head. I have found a parachuting helmet that seems ideal - and is >very comfortable. Now I want to add comms. I was going to use a Halo >headset, but its a problem sticking the ear plugs in your ears >before putting the helmet on. At the weekend I was at a motorcycle >show and was talking with an intercom maker. He sold me a kit to add >comms to a motorcycle helmet, including an electret boom mic and a >pair of thin speakers that fix inside the helmet. He didn't know the >impedance of the speakers, but suspects they are quite low. I said I >needed 600 ohms - his reply was that it wouldn't be a problem. The >audio system is quite simple - Becker AR4201 straight to the >headset. The Becker manual says: >Receiver data ... Rated output: for speaker operation: >at 13.75 V nominal operating voltage >= 3 W at 4 ohms >at 10.0 V operating voltage (emergency mode) >= 1.5 W at 4 ohms >with headset connected: >at 13.75 V nominal operating voltage >= 100 mW at 600 ohms >at 10.0 V operating voltage (emergency mode) >= 30 mW at 600 ohms From your post, it is unclear if you plan on connecting your helmet speakers to the speaker output, or the headphone output. It would be inappropriate to connect them to the HP output, as they would excessively load the receiver if connected to an output designed to feed a 600 ohm load. Were you to connect them to the speaker output, loading would not be an issue, but you may find level control to be difficult as the speakers would be much closer to your ear than cabin mounted transducer(s). Some series resistance would likely be helpful and desired when connected to the speaker output, but used as helmet headphones. Additionally, if the radio provides speaker muting during xmit, you would have no 'sidetone'. Something else to consider. >So the question is, how are these speakers that I am about to stick >into my helmet going to react when the radio output is fed to them? >If their impedance is low I'm guessing that will impact the volume, >so I imagine I will have to turn the radio volume up? It a noisy >airplane and is already up fairly high. Can I add some resistors to >help out? Do I connect both speakers to the tels output (doesn't >that cut the already low impedance in half?) Are all electret mics the same? > >Thanks, Peter ------------------------------------------------------------------------------------- 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.