---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 05/27/03: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:33 AM - Email (Peter Laurence) 2. 06:40 AM - Re: Email (Larry Bowen) 3. 06:59 AM - Re: Email (Freddie Freeloader) 4. 07:47 AM - Re: DIN connectors? (Robert L. Nuckolls, III) 5. 09:14 AM - Re: Email (Greg Young) 6. 09:36 AM - XPDR antenna question (Gilles.Thesee) 7. 10:00 AM - Re: Email (Phil Birkelbach) 8. 11:04 AM - Re: Email (Jeffrey) 9. 03:41 PM - Re: RFI and Grounds... Long (Canyon) 10. 03:48 PM - dimmer circuit (Jim Pack) 11. 08:15 PM - Re: Re: Diode failures and "Reliable Systems" (David Carter) ________________________________ Message 1 _____________________________________ Time: 06:33:02 AM PST US From: Peter Laurence Subject: AeroElectric-List: Email --> AeroElectric-List message posted by: Peter Laurence Sorry about the off topic but.. This is for any of the computer/internet Gurus on the listwho might be able to shed some light on this subject. I'm using a T1 line at my office and get all the mail from the list. However, at home I'm connected to a cable modem and receive a few pieces of mail and never see Bob's mail. Cable co. say they can't help. Peter do not archive ________________________________ Message 2 _____________________________________ Time: 06:40:50 AM PST US Subject: Re: AeroElectric-List: Email From: "Larry Bowen" --> AeroElectric-List message posted by: "Larry Bowen" Different mail clients? Perhaps the home mail client is deleting Bob mail, thinking it is junk mail.... - Larry Bowen Larry@BowenAero.com http://BowenAero.com Peter Laurence said: > --> AeroElectric-List message posted by: Peter Laurence > > > Sorry about the off topic but.. > > This is for any of the computer/internet Gurus on the listwho might be > able to shed some light on this subject. > > I'm using a T1 line at my office and get all the mail from the list. > However, at home I'm connected to a cable modem and receive a few pieces > of mail and never see Bob's mail. > > Cable co. say they can't help. > > Peter > > do not archive ________________________________ Message 3 _____________________________________ Time: 06:59:05 AM PST US From: Freddie Freeloader Subject: Re: AeroElectric-List: Email --> AeroElectric-List message posted by: Freddie Freeloader Hello Peter, Have you subscribed to the list twice, once for your work address and once for your home address? -- Best regards, Freddie mailto:lists@stevet.net Tuesday, May 27, 2003, 6:33:00 AM, you wrote: -->> AeroElectric-List message posted by: Peter Laurence PL> Sorry about the off topic but.. PL> This is for any of the computer/internet Gurus on the listwho might be able to shed some light on this subject. PL> I'm using a T1 line at my office and get all the mail from the list. However, at home I'm connected to a cable modem and receive a few pieces of mail and never see Bob's mail. PL> Cable co. say they can't help. PL> Peter PL> do not archive ________________________________ Message 4 _____________________________________ Time: 07:47:53 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: DIN connectors? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 07:24 PM 5/26/2003 -0700, you wrote: >--> AeroElectric-List message posted by: "Dan Checkoway" > >Thanks much for the response and explanation of this stuff (and also for the >response on the diodes). > >Question...have you ever used a miniature 5-pin DIN connector in an aircraft >application? I was thinking it would be ideal as a Ray Allen trim servo >5-wire connector, but I bailed on the idea because of the length of the >connector and the lack of a "detent" -- and my being generally unsure about >the connector's durability in a high-vibration, possibly high-moisture >setting. I considered the miniature DIN connectors when I crafted the comic book at http://www.aeroelectric.com/articles/macservo/macservo.html They're probably okay but much more difficult for the neophyte solder slinger to get a good installation and they're not a great deal smaller than the d-sub illustrated. D-subs are my personal favorites . . I try to make that connector work first before dragging out catalogs for alternatives. Bob . . . ________________________________ Message 5 _____________________________________ Time: 09:14:48 AM PST US From: "Greg Young" Subject: RE: AeroElectric-List: Email --> AeroElectric-List message posted by: "Greg Young" Sounds like your office e-mail program (Outlook, Eudora, etc.) is deleting the mail from the mail server after it retrieves it. When you get home all you see are messages that have arrived since the last time you retrieved mail from the office. It has nothing to do with your line type or speed. If you are using Outlook or Outlook Express, drill down from the Tools/Accounts menu to the Advanced tab on E-Mail settings (the menu path varies with versions.) You'll find a checkbox that says "Leave a copy of messages on the server" and under that a checkbox for "Remove from server after X days". The combination controls whether and how long your messages remain on your ISP's mail server. I choose to have my office machine control the deletion so I have both boxes checked with a 3 day delay. My home machine and my laptop (for travel) have only the 1st box checked so they never delete any messages. Set the delay based on your mail account rules and the volume of mail you receive. Other e-mail programs should have similar settings. The trick is to leave the messages on the mail server long enough to retrieve them with all your other machines but not so long as to reach your mail account limit. Regards, Greg Young - Houston (DWH) RV-6 N6GY ...project Phoenix Navion N5221K - just an XXL RV-6A > > --> AeroElectric-List message posted by: Peter Laurence > --> > > Sorry about the off topic but.. > > This is for any of the computer/internet Gurus on the listwho > might be able to shed some light on this subject. > > I'm using a T1 line at my office and get all the mail from > the list. However, at home I'm connected to a cable modem and > receive a few pieces of mail and never see Bob's mail. > > Cable co. say they can't help. > > Peter > > do not archive > ________________________________ Message 6 _____________________________________ Time: 09:36:07 AM PST US From: "Gilles.Thesee" Subject: AeroElectric-List: XPDR antenna question --> AeroElectric-List message posted by: "Gilles.Thesee" Hi Bob and all, This is an installation question. I'm intending to install the transponder antenna in the fiber glass fairing below the tail. The ground plane is to be an aluminum cross, with the lateral arms bent to follow the fairing skin, and the antenna in the middle. Are there any drawbacks with this idea ? I posted some picture of the cardboard model at : http://gilles.thesee.free.fr/temp/DSCF1543.JPG http://gilles.thesee.free.fr/temp/DSCF1544.JPG http://gilles.thesee.free.fr/temp/DSCF1545.JPG http://gilles.thesee.free.fr/temp/DSCF1546.JPG Thanks, Gilles ________________________________ Message 7 _____________________________________ Time: 10:00:46 AM PST US From: "Phil Birkelbach" Subject: Re: AeroElectric-List: Email --> AeroElectric-List message posted by: "Phil Birkelbach" You could also try IMAP instead of POP3 as the retrieval protocol. IMAP is much more sophisticated as it keeps the messages on the server. You can create folders, and move messages to them. IMAP also keeps up with which messages have been read so that when you get home you see the same messages but you don't have to remember which ones you have read. I don't know if your ISP will support IMAP or not but if it will then this is a better protocol. The drawback is that you will use up your disk quota faster because it is not removing the messages from the server like POP3 does. Godspeed, Phil ----- Original Message ----- From: "Greg Young" Subject: RE: AeroElectric-List: Email > --> AeroElectric-List message posted by: "Greg Young" > > Sounds like your office e-mail program (Outlook, Eudora, etc.) is deleting > the mail from the mail server after it retrieves it. When you get home all > you see are messages that have arrived since the last time you retrieved > mail from the office. It has nothing to do with your line type or speed. If > you are using Outlook or Outlook Express, drill down from the Tools/Accounts > menu to the Advanced tab on E-Mail settings (the menu path varies with > versions.) You'll find a checkbox that says "Leave a copy of messages on > the server" and under that a checkbox for "Remove from server after X days". > The combination controls whether and how long your messages remain on your > ISP's mail server. I choose to have my office machine control the deletion > so I have both boxes checked with a 3 day delay. My home machine and my > laptop (for travel) have only the 1st box checked so they never delete any > messages. Set the delay based on your mail account rules and the volume of > mail you receive. Other e-mail programs should have similar settings. The > trick is to leave the messages on the mail server long enough to retrieve > them with all your other machines but not so long as to reach your mail > account limit. > > Regards, > Greg Young - Houston (DWH) > RV-6 N6GY ...project Phoenix > Navion N5221K - just an XXL RV-6A > > > > > > --> AeroElectric-List message posted by: Peter Laurence > > --> > > > > Sorry about the off topic but.. > > > > This is for any of the computer/internet Gurus on the listwho > > might be able to shed some light on this subject. > > > > I'm using a T1 line at my office and get all the mail from > > the list. However, at home I'm connected to a cable modem and > > receive a few pieces of mail and never see Bob's mail. > > > > Cable co. say they can't help. > > > > Peter > > > > do not archive > > > > ________________________________ Message 8 _____________________________________ Time: 11:04:16 AM PST US From: "Jeffrey" Subject: Re: AeroElectric-List: Email --> AeroElectric-List message posted by: "Jeffrey" Phil's absolutely right, IMAP is the way to go for multiple homed email accounts. I doubt though your ISP is going to give you an IMAP account. It would take up a bunch of space on their server and if they do that for everyone there going to have to expend a lot of resources keeping it backed up and available and growing with demand. The best thing to do is to go with Greg's suggestion, and leave the copies on the server for three days. Do not archive. Jeff (RV-8, Wings) ________________________________ Message 9 _____________________________________ Time: 03:41:13 PM PST US From: Canyon Subject: Re: AeroElectric-List: RFI and Grounds... Long --> AeroElectric-List message posted by: Canyon Canyon wrote: >1. Is there any such thing as a short circuit? Gone longer than I thought I'd be this weekend. Getting back to the perspective I had hoped to impart here, the short answer is it depends on how short it needs to be. If you are dealing in power circuits it may not be critical to performance that a connection be perfect and pure. Therefore, sometimes just connecting to the right general ground potential can be good enough. OTOH, if you're dealing with small signals, processing millivolts to nanovolts or concerned with measuring or detecting microamps to picoamps, generally speaking, there ain't no such thing as a short circuit. What you may need is as good a connection to a common point as you can figure out how to build and good separation of various return currents. How often does this happen with aircraft? Not often enough to be fearful of it, but I'd bet often enough to require one to be attentive to detail. Example areas in which to be attentive to detail would be with such things as the nav/com and other avionics. You're not likely to get in trouble with the battery mains, alternator circuits and such if you don't mix the return paths of the small signal devices in with these power circuit returns. Ideally you want any current flowing directly to sensitive devices to flow back on the return line as directly to the power source as possible without intervening currents flowing through that same return path from other devices. In fact, this ideal is the basis for GFI devices which have saved many lives in plain old residential power environments. Bob offers a great solution for many with the idea of feeding power through the firewall on a bolt, with avionics returns on the cockpit side and power stuff on the firewall side for the heavier currents. This tends to sort potential errors toward minimum effect. >2. Can two wires occupying the same physical space and carrying equal >currents of opposite polarity radiate energy externally? No, and thinking about that is helpful. If you could accomplish this, then the circuit would neither gather nor emit contaminating external signals. Since it's not physically possible, what's the next best thing? The simple idea is the inspiration for two practical near perfect solutions. First, you can twist two wires evenly with regular, frequent twists and come reasonably close to approximating the two wires occupying the same physical space. To the extent that it's not perfect, it will perform imperfectly. But, for most purposes, this is very effective in the real world as both sides of the circuit are exposed in essentially the same phase and magnitude to both magnetic and electrostatic external signals and the opposite currents in the pair cancel one another. As the wavelengths of AC signals become shorter, the effectiveness is reduced. But there is another way to emulate what we can't really construct -- coax is also inspired by the same simple idea and offers a number of advantages for RF circuits, including our usual VHF and higher frequency signals. There exists even triax and quadrax versions of the same space emulation solutions, similar to the coax for use in specialized areas. So when thinking about how to hook things up for low noise, remember two things: 1: Keep small signal circuits (i.e., RF=typical 1uv or less) paired as close as possible to the ideal of both wires exposed the same way and in the same amount and keep exposure minimized. 2. Always try to return the signal current offered by any avionics (signal) device as directly to the source return as is possible without other intervening currents mixed in with that signal. Almost forgot, shielded twisted pair is often called out in audio and similar applications. The shield is primarily intended for electrostatic decoupling of the wire pair. All you really need to do is hook up one end of that shield to drain off any charge to a proper source return point. A whiteboard would be a lot easier for explaining this kind of thing, but I hope someone finds this useful. Steve ________________________________ Message 10 ____________________________________ Time: 03:48:28 PM PST US From: "Jim Pack" Subject: AeroElectric-List: dimmer circuit --> AeroElectric-List message posted by: "Jim Pack" Perhaps I have put the cart before the horse, but I would like to make a dimmer circuit for my annunciator panel (Which has already been cut into my panel). Is anyone able/willing to suggest a scematic for the dimmer circuit? I have 6 LEDs & a single mini switch that can control it. This is the explanation of how each are proposed to be connected. Label Intent How connected Main Alt Fail Warn of Alt Fail hooked up to the LR3 indicator circuit Aux Alt Fail Warn of Alt Fail hooked up to the LR3 indicator circuit X-Feed On Warn of engaged X-feed Hooked up per Z-14 diagram between posts 5 and 2 on the crossfeed switch. Starter On Warn of stuck starter connected to the I terminal on the Starter Contactor (S702-1) and Ground. Oil Pressure Low Warn of low oil pressure connected to the I terminal on the Oil pressure switch (S710-1) and the Aux Bus Fuse Box. A/P On Warn that A/P is engaged (light out, not engaged) Connected to the Autopilot Control unit power and Ground. Thanks, Jim ________________________________ Message 11 ____________________________________ Time: 08:15:56 PM PST US From: "David Carter" Subject: Re: AeroElectric-List: Re: Diode failures and "Reliable Systems" --> AeroElectric-List message posted by: "David Carter" Bob responded "excellently" to David Carter's story about a diode failure, then asked the question at the end: > Going back to the 2-cent diode bringing down $millions$ worth of equipment. How is this anecdote relevant to how a $5 diode > is bolted to your airplane? > > Bob . . . David replies: The diode in Z13 that passes Main bus power to E-bus isn't relevant to the million dollar anecdote - and poses zero threat to my airplane. Since I sent that e-mail, I've engaged my brain a bit more tightly (learning how to "think like an electron"?) and realized that the switch I proposed - paralleling around the "failable" diode - "in case it failed" (open), added NOTHING - it simply duplicated the existing "E-bus switch" in Z-13 - it would pass power from main bus to e-bus. - If that diode opened, killing my e-bus radios, etc, I didn't need the proposed switch - I only needed to close the "E-bus switch" shown in Z-13 to power the E-bus from the other side (left side) of the Main Battery Contactor. I apologize for being a bit slow at this stuff. It's getting clearer as I "exercise" my rusty, dusty electron knowledge. Seems like I had "tunnel vision" on a particular part of the schematic, started "what if'ing", and lost sight of the "big picture". David Carter DO NOT ARCHIVE [ some more of Bob's response follows, to show the "thread" ] We've all heard about the nation that was lost for want > of a nail in a horseshoe . . . a classic analogy of > cascaded failures. There is always potential and even > probability that one failure will propagate to the > destruction of other components of a system. If any > single failure can take the system down, our consideration > as flight-system designers is to build firewalls between > the failed system and the rest of the aircraft. For > most instances, a fuse or circuit breaker is all that's > needed to prevent the worst kind of failure in any one > system from having a deleterious effect on other systems. > > Given that the anecdote cites a diode as the > first event in this cascade failure, is this > a rational reason for extra-ordinary attention > to the use of diodes in our little airplanes? > > Further, is there anything to suggest that > other components are not equally deserving > of similar attention. It's conceivable that > the very same story could be repeated with the > phrase "2-cent resistor" substituted for "2-cent > diode." > > Sooo . . . rather than wrap ourselves around > the axles of reliability studies that take lots > of research, time and probably don't mean much > anyhow, the OBAM community has deduced that > it's easier to ASSUME that parts of our > system are going to fail and that the > goal is to configure for failure tolerance > as opposed to failure proof. Something > akin to breeding war horses that fight well > on three legs. > > Yup, that diode between the main-bus and e-bus > is NOT IMMUNE FROM FAILURE. In what ways can > it fail? (OPEN or SHORT). How do we know it > has failed (E-BUS STUFF GOES DARK for open > and (E-BUS ALT FEED TEST IN PREFLIGHT POWERS > THE MAIN BUS - for shorted). What are the > consequences of either failure mode? (IF > SHORTED WHILE AIRBORNE - probably not > noticed . . . but we'll catch it at next > preflight) (IF OPEN WHILE AIRBORNE - e-bus > goodies go dark and we have to close the > alternate feedpath switch for continued > operation). > > Okay, assuming you can deduce no errors > of reasoning in the analysis above, how does > this affect your concerns about diode > reliability in this particular case? > > If failure concerns are adequately addressed > we can turn our attention to reducing likelihood > of failure as a sort of icing-on-the-cake . . . > i.e. were not trying to improve reliability > with an eye on flight comfort but more as > a reduced maintenance issue. > > The smallest diode array that comes in the > package I suggest is rated at 25A . . . you can > buy these rectifier arrays in ratings up to > 35A. Sooo . . . unless you have everything > but the kitchen sink powered from the e-bus, > our diode is very adequately de-rated. > > The lowest voltage offered by any diode manufacturer > is 50V . . . plenty of headroom for our 14V > application. These critters have a voltage drop > so they dissipate heat. Can't hang 'em out in > the air . . . so bolt it down to a metallic > surface. > > Wrap-up: We've made a considered selection of > the component and its installation with a > eye toward robustness. Further, we've > deduced that failure of the component > is no more than a nuisance. > > Going back to the 2-cent diode bringing > down $millions$ worth of equipment. How is > this anecdote relevant to how a $5 diode > is bolted to your airplane? > > Bob . . . > >