AeroElectric-List Digest Archive

Thu 01/25/07


Total Messages Posted: 16



Today's Message Index:
----------------------
 
     1. 02:42 AM - Re: Chronically low voltage (Kevin Horton)
     2. 04:23 AM - Re: What's advantage of conductive fuel hose? (Robert L. Nuckolls, III)
     3. 04:35 AM - Re: Chronically low voltage (Robert L. Nuckolls, III)
     4. 05:01 AM - Re: Timer module (Carlos Trigo)
     5. 05:18 AM - Re: Timer module (Carlos Trigo)
     6. 08:18 AM - Re: SD-8 Alternator Wiring (Robert L. Nuckolls, III)
     7. 08:37 AM - Re: Chronically low voltage (McFarland, Randy)
     8. 10:18 AM - Re: What's advantage of conductive fuel hose? (Bill McMullen)
     9. 10:20 AM - Re: IR alternators in airplanes (JUST say NO to OV relays) ()
    10. 10:53 AM - Re: Re: IR alternators in airplanes (JUST say NO to OV relays) (john@ballofshame.com)
    11. 10:58 AM - Homemade Audio Panel (tacaruth@dybb.com)
    12. 11:11 AM - Re: What's advantage of conductive fuel hose? ()
    13. 03:58 PM - Re: Homemade Audio Panel (B Tomm)
    14. 04:43 PM - Re: Homemade Audio Panel (Dave N6030X)
    15. 05:25 PM - Re: Homemade Audio Panel (john@ballofshame.com)
    16. 05:30 PM - Re: What's advantage of conductive fuel hose? (rtitsworth)
 
 
 


Message 1


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    Time: 02:42:52 AM PST US
    From: Kevin Horton <khorton01@rogers.com>
    Subject: Re: Chronically low voltage
    On 24 Jan 2007, at 22:48, Robert L. Nuckolls, III wrote: > <nuckollsr@cox.net> > > Start the engine but leave EVERYTHING electrical > turned off except battery and alternator. The engine > monitor should IMMEDIATELY show 14.2 or more volts > and alternator output current should peak up but > come down pretty quickly . . . probably under 10 > amps in a minute or so. > > If you don't have 14 volts but do have some measurable > output current, the alternator is bad. This appears to assume that the engine monitor is on a bus that sees the full alternator voltage. If the engine monitor is on a bus that gets its power via a conventional diode, then you can subtract about 0.6 volts from the above values. Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://www.kilohotel.com/rv8


    Message 2


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    Time: 04:23:30 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: What's advantage of conductive fuel hose?
    Dunno . . . I'll ask around the power-plant and fuel systems guys today. Bob . . . At 07:33 PM 1/24/2007 +0000, you wrote: > >I am working on final plumbing of Europa / Rotax 914 fuel system. > >The system is a plastic rotomolded fuel tank, mostly rubber automotive >5/16" fuel injector hose, 2 vane style electric fuel pumps. > >I have plumbing completed to 2 Flowscan 201B fuel flow sensors (add flow >in, and subtract return to tank). > >I want to use Aeroquip 666 to run from the 201B through firewall to the >fuel pressure regulator, and then from the fuel pressure regulator return, >through the firewall to the return 201B. > >I read somewhere that the 666 hose has stainless braid on the outside, >Teflon hose on the inside and it is electrical conductive. Didn't think >much about it, I just assumed that they were talking about the braid. > >After getting a sample of the hose, I see that they have the internal wall >of the hose coated with a black substance that is probably;y electrical >conductive. > >2 Questions: > >1) Why would you want the internal wall of a hose electrical conductive? > >I read 43.13 and they really don't tell much as to why. If it is static >discharge, is that really important? There are plenty of cars on the road >with rubber fuel lines? > >Perhaps for lightening strike?? > >If I use this hose in my system (approx 4 feet in and 4 feet out) am I >creating any problems? Aeroquip makes very close to the same hose for Auto >racing guys without the black conductive coating. You see this as a more >appropriate hose for my system/plane? > >2) More of a concern I think is there is this thin black coating inside a >Teflon tube. If it begins to flake off, it could cause much problems. > >Has anyone had any flaking problems?? I can easily see causing an upset to >this coating when installing hose ends. > >Thx. >Ron Parigoris > > >-- >10:31 PM > > >-- incoming mail is certified Virus Free. >Checked by AVG. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 3


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    Time: 04:35:25 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Chronically low voltage
    At 05:40 AM 1/25/2007 -0500, you wrote: > >On 24 Jan 2007, at 22:48, Robert L. Nuckolls, III wrote: > >><nuckollsr@cox.net> >> >> Start the engine but leave EVERYTHING electrical >> turned off except battery and alternator. The engine >> monitor should IMMEDIATELY show 14.2 or more volts >> and alternator output current should peak up but >> come down pretty quickly . . . probably under 10 >> amps in a minute or so. >> >> If you don't have 14 volts but do have some measurable >> output current, the alternator is bad. > >This appears to assume that the engine monitor is on a bus that sees >the full alternator voltage. If the engine monitor is on a bus that >gets its power via a conventional diode, then you can subtract about >0.6 volts from the above values. Good put sir! Thanks. Bob . . .


    Message 4


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    Time: 05:01:16 AM PST US
    From: "Carlos Trigo" <trigo@mail.telepac.pt>
    Subject: Re: Timer module
    Peter, and all electronic experts Could it be easier (and enough) to replace the Relay (6-9V) of the Timer circuit by a 12/14V Relay, and then you already can use it with 12/14V power source ? Carlos From: "Peter Laurence" <PLaurence@the-beach.net> > > Carlos, > > Here is one way of regulating the 9 volts. See: > http://www.uoguelph.ca/~antoon/circ/ps-lm317.html > > > Peter > >> In the circuit design shown in >> >> http://www.uoguelph.ca/~antoon/circ/relay1h.html >> >> the power source is indicated at 9 V. >> Please forgive an electronics ignorant question, but what should be done >> to >> connect this circuit to 12/14 V ? >> >> Carlos >>


    Message 5


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    Time: 05:18:05 AM PST US
    From: "Carlos Trigo" <trigo@mail.telepac.pt>
    Subject: Re: Timer module
    Dick Thank you very much for your elaborate and knowledgeable answer. I hadnt read it when I put my today's previous post, asking about the substitution of the relay. Youre right that, at this moment, all you explained is "too much for me to absorb", at least right away, but since I'm in this group to learn, I will try to do exactly that by studying the circuit and your answer, and then come back with additional rookie questions. After all, this is nothing but the normal process of learning .... Thanks Carlos ----- Original Message ----- From: "Richard E. Tasker" <retasker@optonline.net> Sent: Thursday, January 25, 2007 4:32 AM Subject: Re: AeroElectric-List: Timer module > <retasker@optonline.net> > > Probably nothing. The LMC555 is rated to 15V. The characteristic of the > 555 series is that the timing is relatively insensitive to the supply > voltage. If you run it from 12-14V you will have to choose a relay that > is rated at more than the 6V the schematic shows and has a resistance of > 1000 ohms or more. Depending on what you want to control with the relay, > you could also use an NPN transistor or FET to control the load in place > of the relay. > > The only weakness in the circuit shown is that if you get transients on > your aircraft voltage you might destroy the LMC555 - depends on the length > and voltage of the transient. You could mitigate this problem with a > small series resistor and filter capacitor to ground. If you want it to > be bulletproof a zener in parallel with the capacitor would do it. > > I know this might be too much for you to absorb :-) . If you have other > questions, please feel free to ask. > > Dick > Carlos Trigo wrote: >> >> In the circuit design shown in >> >>> >>> http://www.uoguelph.ca/~antoon/circ/relay1h.html >>> >> >> the power source is indicated at 9 V. >> Please forgive an electronics ignorant question, but what should be done >> to connect this circuit to 12/14 V ? >> >> Carlos >>


    Message 6


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    Time: 08:18:44 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: SD-8 Alternator Wiring
    At 11:11 AM 1/24/2007 -0500, you wrote: >Bob, > >I plan to use your Z-12 diagram as the basis of a 2-alternator, single >forward-mounted battery system in my RV-8A. I will have an endurance bus >with the AFS 3500, Garmin 496, SL30, Auto Pilot Mstr (TruTrak ADI Pilot >for back up attitude), Pitot Heat, Boost Pump, Pitch and Roll trim, and >one Cockpit Flood Light running on the SD-8, realizing that use of pitot >heat will eventually drain the battery. I am trying to understand the >differences in operating principles of the B&C L-60 and the SD-8, >particularly in the need for the 5 amp field circuit breaker. Does the >SD-8 need one? You lost me. Z-12 is specifically for the SD-20 on the vacuum pump pad and some larger alternator on the front of the engine. Are you sure you're not referring to Z-13? If Z-13, the SD-8 "field" breaker obviously does not control a real field . . . however, functionality of this breaker is the same as for an externally regulated machine where opening this breaker shuts off the associated alternator. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 7


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    Time: 08:37:08 AM PST US
    From: "McFarland, Randy" <Randy.McFarland@novellus.com>
    Subject: Chronically low voltage
    Thanks all. Off to the hangar to measure / test as suggested. Will report back the results. R -----Original Message----- From: Robert L. Nuckolls, III [mailto:nuckollsr@cox.net] Sent: Thursday, January 25, 2007 4:35 AM Subject: Re: AeroElectric-List: Chronically low voltage <nuckollsr@cox.net> At 05:40 AM 1/25/2007 -0500, you wrote: <khorton01@rogers.com> > >On 24 Jan 2007, at 22:48, Robert L. Nuckolls, III wrote: > >><nuckollsr@cox.net> >> >> Start the engine but leave EVERYTHING electrical >> turned off except battery and alternator. The engine >> monitor should IMMEDIATELY show 14.2 or more volts >> and alternator output current should peak up but >> come down pretty quickly . . . probably under 10 >> amps in a minute or so. >> >> If you don't have 14 volts but do have some measurable >> output current, the alternator is bad. > >This appears to assume that the engine monitor is on a bus that sees >the full alternator voltage. If the engine monitor is on a bus that >gets its power via a conventional diode, then you can subtract about >0.6 volts from the above values. Good put sir! Thanks. Bob . . .


    Message 8


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    Time: 10:18:19 AM PST US
    Subject: Re: What's advantage of conductive fuel hose?
    From: "Bill McMullen" <CircleM@telusplanet.net>
    I think this article gives a good start for answering this question ... basically the conductive liner is preventing static sparks between the inside of the hose and the braid. http://www.sacskyranch.com/statichose.htm Read this topic online here: http://forums.matronics.com/viewtopic.php?p=90398#90398


    Message 9


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    Time: 10:20:57 AM PST US
    From: <gmcjetpilot@yahoo.com>
    Subject: Re: IR alternators in airplanes (JUST say NO to OV
    relays) >From: "Robert L. Nuckolls, III" >>Can I use the LR3C from B&C to prevent OV >>problems? Or, does someone else sell such a >>device? >> >>Thanks David Weber >Internally regulated alternators are a what-you- >see-is-what-you-get. If it is your desire to have >these marvelous-but-not-perfect devices operated >within the design goals we've been using for >externally regulated alternators then some form of >external adaptation is necessary necessary. What does that mean? Yea see-is-what-you-get inside of an internal regulator: http://img103.imageshack.us/my.php?image=slide2jo1.jpg Here is a typical external or LR3C regulator http://img62.imageshack.us/my.php?image=slide7bj9.jpg or http://img269.imageshack.us/my.php?image=slide6it5.jpg OV protection is for externally regulated alternators, NOT internally regulated. WHY? Because internally regulated alternators are not designed for external protection. External regulators are old fashioned, even the LR3C needs over voltage protection because they have no protection at all (unless you use a modern external voltage regulator, like a V120 below). If you want OV protection for an Externally regulated alternator use this regulator, http://195.125.241.148/cgi-win/product.exe?V1200 OR if you are worried about your I-VR alternator, buy a plane power alternator from Plane power, which Vans Aircraft sells. http://www.plane-power.com/ or http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1169746824-338-558&browse=engines&product=alternator-kit The level of fear of OV is not justified by the facts and its based on ignorance, urban legend and folklore. Very few I-VR's have OV events and when they do they are mild and easily controlled with RPM or adding extra electrical load (say landing lights) or its just not an issue. If you want to add an OV monster relay on your plane's I-VR ND alternator, please consider NOT and doing the above. The choice is about 10% technical, 40% preference and 50% emotional, but OV relays are old time news. The emotional part is what some vendors like B&C use as a sales pitch with dark and stormy night stories. If you are VFR and have modern avionics that can handle 10-32 volts and 60 volts surge, as most can, than considered NOT using an OV relay. When you hear another OV happened with an I-VR, ask really, what happened? The reality is not as bad as the imagination might lead. (*Call your manufacture to confirm. If operational voltage is listed as 10-32 volts in the owners manual, chance is the electronics has filtered protected power supply.) Just say NO to BIG, FAT, Heavy over voltage relays. This is antiquated technology based on the old days of externally regulated alternators that had OV events and BAD ones at that. Modern OV alternators are less likely to have over voltage with their ON BOARD sophisticated regulators that monitor things like temperature, which external regulators could not ever dream of. JUST SAY NO TO OV RELAYS, WELCOME TO THE 21st CENTRY, I-VR ALTERNATORS OR SOLID STATE OV PROTECTED EXTERNAL VOLTAGE REGULATORS. No offense to Bob, but OV relays are a step backwards. Cheers, George --------------------------------- Never miss an email again! Yahoo! Toolbar alerts you the instant new Mail arrives. Check it out.


    Message 10


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    Time: 10:53:54 AM PST US
    Subject: Re: IR alternators in airplanes (JUST say
    NO to OV relays)
    From: john@ballofshame.com
    External OV protection with an external regulator is solid state. When the crowbar trips, the field is grounded, thus driving the alternator output to 0. The fact that the field circuit breaker pops some time later is beside the point. If you wanted to you could wire the the field with a massive bus bar and leave the circuit breaker out completely. The field wire will be at 0 potential going into the regulator because it's grounded. Of course, doing this would destroy your battery in short order. Putting OV protection on internal regulators requires the relay to work and is much kludgier. Though the module might be the same, they function COMPLETELY differently and shouldn't be confused. -John www.ballofshame.com >>From: "Robert L. Nuckolls, III" > >>>Can I use the LR3C from B&C to prevent OV >>>problems? Or, does someone else sell such a >>>device? >>> >>>Thanks David Weber > > >Internally regulated alternators are a what-you- >>see-is-what-you-get. If it is your desire to have >>these marvelous-but-not-perfect devices operated >>within the design goals we've been using for >>externally regulated alternators then some form of >>external adaptation is necessary necessary. > > What does that mean? > > Yea see-is-what-you-get inside of an internal > regulator: > > http://img103.imageshack.us/my.php?image=slide2jo1.jpg > > Here is a typical external or LR3C regulator > > http://img62.imageshack.us/my.php?image=slide7bj9.jpg > or > http://img269.imageshack.us/my.php?image=slide6it5.jpg > > > OV protection is for externally regulated > alternators, NOT internally regulated. WHY? > Because internally regulated alternators are not > designed for external protection. External > regulators are old fashioned, even the LR3C needs > over voltage protection because they have > no protection at all (unless you use a modern > external voltage regulator, like a V120 below). > > > If you want OV protection for an Externally > regulated alternator use this regulator, > > http://195.125.241.148/cgi-win/product.exe?V1200 > > OR if you are worried about your I-VR alternator, > buy a plane power alternator from Plane power, > which Vans Aircraft sells. > > http://www.plane-power.com/ > or > http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1169746824-338-558&browse=engines&product=alternator-kit > > > The level of fear of OV is not justified by the facts > and its based on ignorance, urban legend and folklore. > Very few I-VR's have OV events and when they do > they are mild and easily controlled with RPM or > adding extra electrical load (say landing lights) or > its just not an issue. > > If you want to add an OV monster relay on your > plane's I-VR ND alternator, please consider NOT > and doing the above. > > > The choice is about 10% technical, 40% preference > and 50% emotional, but OV relays are old time news. > > The emotional part is what some vendors like B&C > use as a sales pitch with dark and stormy night > stories. If you are VFR and have modern avionics > that can handle 10-32 volts and 60 volts surge, as > most can, than considered NOT using an OV relay. > > When you hear another OV happened with an I-VR, > ask really, what happened? The reality is not as > bad as the imagination might lead. > > (*Call your manufacture to confirm. If operational > voltage is listed as 10-32 volts in the owners manual, > chance is the electronics has filtered protected power > supply.) > > Just say NO to BIG, FAT, Heavy over voltage > relays. This is antiquated technology based on the > old days of externally regulated alternators that had > OV events and BAD ones at that. Modern OV > alternators are less likely to have over voltage > with their ON BOARD sophisticated regulators > that monitor things like temperature, which > external regulators could not ever dream of. > > JUST SAY NO TO OV RELAYS, WELCOME > TO THE 21st CENTRY, I-VR ALTERNATORS > OR SOLID STATE OV PROTECTED EXTERNAL > VOLTAGE REGULATORS. > > No offense to Bob, but OV relays are a step backwards. > > > Cheers, George > > > --------------------------------- > Never miss an email again! > Yahoo! Toolbar alerts you the instant new Mail arrives. Check it out.


    Message 11


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    Time: 10:58:08 AM PST US
    From: tacaruth@dybb.com
    Subject: Homemade Audio Panel
    Hi All, I have an experimental aircraft I built. It currently has one comm radio. I am interested in adding a second comm radio. To do this, one must be able to switch between the radios. The common method for this is to install in audio panel of which there are many versions on the market. The problem with these solutions is that they have lots of switches such as nav radios, dme, adf, etc. Does anyone know if a unit that only has switches for 2 comm radios? The closest I can find is the PMA-4000 which also includes an intercom and 2 nav inputs. I already have an intercom which handles my needs fine. I was thinking of adding a 2 position, 3 circuit switch for radio selection. The 3 circuits would be for audio, mic, and ptt. If I wanted to expand this system, I could add a pair of 2 position, 1 circuit switches to allow the radio that is not selected with the first 3 circuit switch. Any thoughts/comments would be appreciated. Thanks, Tom ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.


    Message 12


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    Time: 11:11:41 AM PST US
    Subject: Re: What's advantage of conductive fuel hose?
    From: <rparigor@SUFFOLK.LIB.NY.US>
    Hello Bob Will appreciate what you find. "> Dunno . . . I'll ask around the power-plant and fuel systems > guys today." I uncovered an article: http://www.tc.gc.ca/civilaviation/systemsafety/newsletters/tp3658/PDF/4_2004.pdf That talks about a few helicopter fuel systems "expanding very rapid". Ultimate question, on our plastic Europa, would it be a worthwhile exercise to run anything that conducts to the negative side of the battery that would in essence connect all of them together? If the answer is yes, would it be advisable to run all of these pieces to a single point ground (make a separate single point ground and run it direct to battery that is always connected)? Bits and pieces that could be connected: aluminium fuel cap receptacle aluminium fuel elbow between filler and tank (~1 foot long) 2 aluminium fuel outlets from plastic tank that have 1 foot copper tubes for water draining Brass barb fittings 2 flowscan 201B fuel flow senders 2 lengths of Aeroquip 666 hose 2 aluminium water drain connectors The things that can not be grounded Plastic Rotomolded fuel filler Rotomolded fuel tank 5/16" fuel injector hose, and plenty of it (don't think it conducts very well?) Very sketchy tale I heard about a Europa lost in a fire when refueling?? >From a hands on Europa Guru, said just wipe fuel filler area with a water damp cloth rag before refueling and don't worry bout it, been refueling plastic aeroplanes and boats for years without a problem. Ron Parigoris


    Message 13


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    Time: 03:58:55 PM PST US
    From: "B Tomm" <fvalarm@rapidnet.net>
    Subject: Homemade Audio Panel
    Tom, I don't know of one with only switches for 2 radios (although there probably is one), but there's lots of basic audio panels on ebay. The basic ones go pretty cheap. The following example is one that a do-it-youselfer could start with and repaint/label the front panel for a low cost audio panel. See http://cgi.ebay.com/ebaymotors/BENDIX-KING-KMA-24-Audio-Panel_W0QQitemZ11008 4059554QQihZ001QQcategoryZ90973QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Bevan RV7A just bought a used PS engineering audio panel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of tacaruth@dybb.com Sent: Thursday, January 25, 2007 10:57 AM Subject: AeroElectric-List: Homemade Audio Panel Hi All, I have an experimental aircraft I built. It currently has one comm radio. I am interested in adding a second comm radio. To do this, one must be able to switch between the radios. The common method for this is to install in audio panel of which there are many versions on the market. The problem with these solutions is that they have lots of switches such as nav radios, dme, adf, etc. Does anyone know if a unit that only has switches for 2 comm radios? The closest I can find is the PMA-4000 which also includes an intercom and 2 nav inputs. I already have an intercom which handles my needs fine. I was thinking of adding a 2 position, 3 circuit switch for radio selection. The 3 circuits would be for audio, mic, and ptt. If I wanted to expand this system, I could add a pair of 2 position, 1 circuit switches to allow the radio that is not selected with the first 3 circuit switch. Any thoughts/comments would be appreciated. Thanks, Tom ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.


    Message 14


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    Time: 04:43:35 PM PST US
    From: Dave N6030X <N6030X@DaveMorris.com>
    Subject: Re: Homemade Audio Panel
    Tom, on my 1960 Mooney they didn't have audio panels back then, so they just wired the outputs of the 2 COM radios together and installed a switch with a relay to control the mic/PTT inputs. I then have an intercom with VOX and a music input to allow me to talk to the copilot and listen to the iPod. When I want to listen to a radio, I turn up its volume. If I want to listen to both radios, I turn up both, realizing them with both switched on, the output volume suffers somewhat. When I transmit on one, I turn the volume down on the other so as not to hear the squeal. It's not the best way, but it's definitely the cheapest way. The next cheapest is probably the RST Engineering audio panel kit http://www.rst-engr.com/rst/catalog/audio_panel.html Dave Morris www.N6030X.com At 11:57 AM 1/25/2007, you wrote: > >Hi All, > >I have an experimental aircraft I built. It currently has one comm >radio. I am >interested in adding a second comm radio. To do this, one must be able to >switch between the radios. The common method for this is to install in audio >panel of which there are many versions on the market. The problem with these >solutions is that they have lots of switches such as nav radios, >dme, adf, etc. > Does anyone know if a unit that only has switches for 2 comm radios? The >closest I can find is the PMA-4000 which also includes an intercom and 2 nav >inputs. I already have an intercom which handles my needs fine. I was >thinking of adding a 2 position, 3 circuit switch for radio selection. The 3 >circuits would be for audio, mic, and ptt. If I wanted to expand this system, >I could add a pair of 2 position, 1 circuit switches to allow the >radio that is >not selected with the first 3 circuit switch. > >Any thoughts/comments would be appreciated. > >Thanks, Tom > >---------------------------------------------------------------- >This message was sent using IMP, the Internet Messaging Program. >


    Message 15


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    Time: 05:25:50 PM PST US
    Subject: Homemade Audio Panel
    From: john@ballofshame.com
    If all you want to do is physically switch between radios, a switch should work fine. If you want to be able to mix and match (talk on one, transmit on the other....talk/listen on one and just listen on the other) this is easily doable with a few bucks worth of parts from Radio Shack. All you need to do is send the audio out from the radios into isolation amplifiers (nothing special about the amps....it's all in how you use them). I'm sure you can find a schematic on the web somewhere and it shouldn't take more than a weekend to assemble, test and package. The isolation amps allow you to have multiple inputs without screwing up the impedence of the load the radios see. If you try and just wire everything together, you'll get funny sounding audio (low power, distorsion etc). Depending on the radio and your tolerance it may or may not be OK. >From there, you can get fancier and add switches to select which audio to listen to (instead of turning them up and down from the volume knob). If I did this, I would setup each input with a 2 position switch - On or Auto. Then a switch for mic/ptt (com1, com2). In "On", the channel is always on. In Auto, it's on if the mic has selected that channel, else it's off. 99% of the time, everthing will be auto. Every now and then, you'll transmit on one channel and recieve on another so you'll have to force the recieve channel to "On". This really would make a nice weekend project. Maybe 2 weekends and a couple of weeknights (and some help from a EE buddy) if it's your first circuit project. -John > > Tom, I don't know of one with only switches for 2 radios (although there > probably is one), but there's lots of basic audio panels on ebay. The > basic > ones go pretty cheap. The following example is one that a do-it-youselfer > could start with and repaint/label the front panel for a low cost audio > panel. See > > http://cgi.ebay.com/ebaymotors/BENDIX-KING-KMA-24-Audio-Panel_W0QQitemZ11008 > 4059554QQihZ001QQcategoryZ90973QQssPageNameZWDVWQQrdZ1QQcmdZViewItem > > Bevan > RV7A just bought a used PS engineering audio panel > > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of > tacaruth@dybb.com > Sent: Thursday, January 25, 2007 10:57 AM > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Homemade Audio Panel > > > Hi All, > > I have an experimental aircraft I built. It currently has one comm radio. > I am interested in adding a second comm radio. To do this, one must be > able > to switch between the radios. The common method for this is to install in > audio panel of which there are many versions on the market. The problem > with these solutions is that they have lots of switches such as nav > radios, > dme, adf, etc. > Does anyone know if a unit that only has switches for 2 comm radios? The > closest I can find is the PMA-4000 which also includes an intercom and 2 > nav > inputs. I already have an intercom which handles my needs fine. I was > thinking of adding a 2 position, 3 circuit switch for radio selection. > The > 3 circuits would be for audio, mic, and ptt. If I wanted to expand this > system, I could add a pair of 2 position, 1 circuit switches to allow the > radio that is not selected with the first 3 circuit switch. > > Any thoughts/comments would be appreciated. > > Thanks, Tom > > ---------------------------------------------------------------- > This message was sent using IMP, the Internet Messaging Program. > >


    Message 16


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    Time: 05:30:03 PM PST US
    From: "rtitsworth" <rtitsworth@mindspring.com>
    Subject: What's advantage of conductive fuel hose?
    I believe non-conductive fuel hose lining builds up static electricity as the fluid flows through it. Then, the static electricity eventually discharges (sparks) out to the exterior braid and thus burns a small hole in the lining (bad). -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Thursday, January 25, 2007 7:21 AM Subject: Re: AeroElectric-List: What's advantage of conductive fuel hose? <nuckollsr@cox.net> Dunno . . . I'll ask around the power-plant and fuel systems guys today. Bob . . . At 07:33 PM 1/24/2007 +0000, you wrote: > >I am working on final plumbing of Europa / Rotax 914 fuel system. > >The system is a plastic rotomolded fuel tank, mostly rubber automotive >5/16" fuel injector hose, 2 vane style electric fuel pumps. > >I have plumbing completed to 2 Flowscan 201B fuel flow sensors (add flow >in, and subtract return to tank). > >I want to use Aeroquip 666 to run from the 201B through firewall to the >fuel pressure regulator, and then from the fuel pressure regulator return, >through the firewall to the return 201B. > >I read somewhere that the 666 hose has stainless braid on the outside, >Teflon hose on the inside and it is electrical conductive. Didn't think >much about it, I just assumed that they were talking about the braid. > >After getting a sample of the hose, I see that they have the internal wall >of the hose coated with a black substance that is probably;y electrical >conductive. > >2 Questions: > >1) Why would you want the internal wall of a hose electrical conductive? > >I read 43.13 and they really don't tell much as to why. If it is static >discharge, is that really important? There are plenty of cars on the road >with rubber fuel lines? > >Perhaps for lightening strike?? > >If I use this hose in my system (approx 4 feet in and 4 feet out) am I >creating any problems? Aeroquip makes very close to the same hose for Auto >racing guys without the black conductive coating. You see this as a more >appropriate hose for my system/plane? > >2) More of a concern I think is there is this thin black coating inside a >Teflon tube. If it begins to flake off, it could cause much problems. > >Has anyone had any flaking problems?? I can easily see causing an upset to >this coating when installing hose ends. > >Thx. >Ron Parigoris > > >-- >10:31 PM > > >-- incoming mail is certified Virus Free. >Checked by AVG. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------




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