---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 10/17/03: 27 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:53 AM - Re: thermistors for low fuel warning (Rick Caldwell) 2. 06:22 AM - Re: thermistors for low fuel warning (Trampas) 3. 07:13 AM - Re: Strobe wire? (Robert L. Nuckolls, III) 4. 07:21 AM - Re: Transponder Main bus or Essential Bus (Robert L. Nuckolls, III) 5. 07:49 AM - Re: thermistors for low fuel warning (Werner Schneider) 6. 08:07 AM - Re: Re: Strobe wire? (Bill Hibbing) 7. 08:12 AM - Re: thermistors for low fuel warning (Trampas) 8. 08:24 AM - Re: thermistors for low fuel warning (John Slade) 9. 08:37 AM - Re: Transponder Main bus or Essential Bus (John R) 10. 09:38 AM - solar battery charger (Richard May) 11. 10:51 AM - solar battery charger (Eric M. Jones) 12. 11:13 AM - Re: solar battery charger (caspainhower@aep.com) 13. 11:56 AM - Re: Transponder Main bus or Essential Bus (Robert L. Nuckolls, III) 14. 11:57 AM - Re: Re: Strobe wire? (Robert L. Nuckolls, III) 15. 11:59 AM - Re: 10856 Wandke (Robert L. Nuckolls, III) 16. 12:00 PM - Re: Re: Strobe wire? (jerb) 17. 12:14 PM - Re: thermistors for low fuel warning (Robert L. Nuckolls, III) 18. 12:23 PM - Current Limiters (PTACKABURY@aol.com) 19. 01:40 PM - Re: thermistors for low fuel warning (Werner Schneider) 20. 01:41 PM - Re: Current Limiters (Matt Prather) 21. 01:47 PM - Re: thermistors for low fuel warning (Joa Harrison) 22. 03:25 PM - Re: thermistors for low fuel warning (Trampas) 23. 03:54 PM - Re: Transponder Main bus or Essential Bus (Tom Brusehaver) 24. 04:43 PM - Re: Need for relays? (jerb) 25. 04:57 PM - Bob, external power receptacle (Jerzy Krasinski) 26. 10:45 PM - Re: Need for relays? (Robert L. Nuckolls, III) 27. 10:47 PM - Re: Need for relays? (kempthornes) ________________________________ Message 1 _____________________________________ Time: 05:53:50 AM PST US From: "Rick Caldwell" Subject: Re: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Rick Caldwell" Joa; I am interested in how you are going to design your low level waring system? Are you looking for a temperature change? Or is their another use for thermistors? If I can help out let me know. Rick Caldwell ----- Original Message ----- From: "Joa Harrison" Subject: AeroElectric-List: thermistors for low fuel warning > --> AeroElectric-List message posted by: Joa Harrison > > > I have the need for two thermistors for low fuel warning. The first is for my homebuilt and needs to be 14 vdc, very affordable, and fairly robust. The second is for a 28vdc certified design (to replace a float switch) and must be made for certified aircraft (or the military). I need info on the first one for my hobby (well, thats what my wife calls it, I prefer to call it my secondary vocation) and the second one is for my day job (and what I call my hobby!) > > > What would you all suggest? > > > Thanks! > > > Joa > > > --------------------------------- > > ________________________________ Message 2 _____________________________________ Time: 06:22:32 AM PST US From: "Trampas" Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Trampas" I found this on the web: Toyota thermistor low fuel circuit description: On a Toyota, they put a thermistor in the gas tank. It's not a potentiometer type sending unit. The thermistor has current and voltage supplied to it and a light bulb is in series with it continuously. This continuously heats up the thermistor and at low fuel levels, the resistance drops causing the indicator light to turn ON as the current goes up. When the thermistor is immersed in fuel, the fuel keeps the thermistor cooled off, the resistance remains high and the indicator light bulb does not light up. Since the indicator always has current flowing through it and the thermistor, it only lights up when the fuel level gets low and uncovers the thermistor. This thermistor line is yellow with a black stripe on my late 90s Here are some other links www.hdk.co.jp/pdf/eng/e023101.pdf www.scully.com/cgi-bin/pdf/60635_desc.pdf Everything mustang has the sensors for $32 www.everythingmustang.com/Merchant2/ merchant.mv?Screen=CTGY&Store_Code=EM&Category_Code=THERME Trampas -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Rick Caldwell Subject: Re: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Rick Caldwell" Joa; I am interested in how you are going to design your low level waring system? Are you looking for a temperature change? Or is their another use for thermistors? If I can help out let me know. Rick Caldwell ----- Original Message ----- From: "Joa Harrison" Subject: AeroElectric-List: thermistors for low fuel warning > --> AeroElectric-List message posted by: Joa Harrison > > > I have the need for two thermistors for low fuel warning. The first is for my homebuilt and needs to be 14 vdc, very affordable, and fairly robust. The second is for a 28vdc certified design (to replace a float switch) and must be made for certified aircraft (or the military). I need info on the first one for my hobby (well, thats what my wife calls it, I prefer to call it my secondary vocation) and the second one is for my day job (and what I call my hobby!) > > > What would you all suggest? > > > Thanks! > > > Joa > > > --------------------------------- > > ________________________________ Message 3 _____________________________________ Time: 07:13:59 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Strobe wire? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > >Comments/Questions: Hi Bob....I have a wing off the plane right now, and >before I re-mount it, I want to run the strobe wires through it from tip >to root. I haven't yet bought the strobes (resistance to Whelan's >ridiculous pricing I expect) but I intend to use Whelan heads probably >with a Nova power supply. > >Can you advise the wire spec that I should run? There are dozens of suitable wires. Problem is that most suppliers no longer offer cut lengths to order. You have to order a whole spool (usually 100' minimum). The wire you're looking for is 18 or 16 AWG triple with overall shield. You might check with local installers of audio and industrial control systems. They may have open spools of something suitable and would be willing to sell you the 40 feet or so that you need. Consider this instead. If you buy a Whelan kit, it will come with the wire. How about running a conduit of Nyloflo or similar tubing from root to tip now. When you get your kit later, it will be easy to run the wires in. I will invite you to join us on the AeroElectric List to continue this and similar discussions. It's useful to share the information with as many folks as possible. A further benefit can be realized with membership on the list. There are lots of technically capable folks on the list who can offer suggestions too. You can join at . . . http://www.matronics.com/subscribe/ Thanks! Bob . . . |---------------------------------------------------| | A lie can travel half way around the world while | | the truth is till putting on its shoes . . . | | -Mark Twain- | |---------------------------------------------------| ________________________________ Message 4 _____________________________________ Time: 07:21:10 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Transponder Main bus or Essential Bus --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" See chapter 17 of the 'Connection or if you don't have the book, download http://www.aeroelectric.com/articles/Rev9/ch17-9.pdf >I agree on the essential bus. But you could just leave it on - it will >consume very little power. It will be ready to use, especially in an >emergency. Repeat after me, "We don't have "EMERGENCIES" in our airplanes, only certified ships are designed and regulated to precipitate EMERGENCIES". > It only consumes non-trivial power when you need to transmit for >a few seconds. >Ernest Kells - RV-9A O235-N2C, Wood Prop > 90 plus % Complete - seat kit arrived today > > > Essential bus - The transponder has an off switch so why sweat it. >Bruce > > www.glasair.org > > > > Which bus would you wire the Transponder to, and why? > > Charlie Kuss > > Bob . . . -------------------------------------------- ( Knowing about a thing is different than ) ( understanding it. One can know a lot ) ( and still understand nothing. ) ( C.F. Kettering ) -------------------------------------------- ________________________________ Message 5 _____________________________________ Time: 07:49:51 AM PST US From: "Werner Schneider" Subject: Re: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Werner Schneider" Interesting approach, would wonder what happens if you have a fuel injected engine with a return line (of "hot" fuel) back into the tanks. I'm using a optical device in my Glastar, works great and as it is LED it needs nearly no power!! http://www.ppavionics.com/LFL.htm Werner ----- Original Message ----- > When the thermistor is immersed in fuel, the fuel keeps the thermistor > cooled off, the resistance remains high and the indicator light bulb does > not light up. ________________________________ Message 6 _____________________________________ Time: 08:07:37 AM PST US From: "Bill Hibbing" Subject: Re: AeroElectric-List: Re: Strobe wire? --> AeroElectric-List message posted by: "Bill Hibbing" ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Strobe wire? > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > > > > >Comments/Questions: Hi Bob....I have a wing off the plane right now, and > >before I re-mount it, I want to run the strobe wires through it from tip > >to root. I haven't yet bought the strobes (resistance to Whelan's > >ridiculous pricing I expect) but I intend to use Whelan heads probably > >with a Nova power supply. > > > >Can you advise the wire spec that I should run? > > There are dozens of suitable wires. Problem is that most > suppliers no longer offer cut lengths to order. You have to > order a whole spool (usually 100' minimum). The wire you're > looking for is 18 or 16 AWG triple with overall shield. You > might check with local installers of audio and industrial > control systems. They may have open spools of something > suitable and would be willing to sell you the 40 feet or > so that you need. > Check www.strobesnmore.com . He can sell you the Nova power supply and cable by the foot. If you're using only 2 strobe heads the XPak 604 will do the job for you. I know a lot of folks are using the 904 but with only 2 heads that power supply (904) reduces the power output. This is not the case with the 604. If you're using more than 2 flash tubes it's a mute point. Just thought I'd pass it along. Bill Glasair SIIS-FT ________________________________ Message 7 _____________________________________ Time: 08:12:54 AM PST US From: "Trampas" Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Trampas" The approach works fine with fuel injected engines as proven by Toyota and other automotive manufactures. Basically it is a thermal dissipation problem. That is the fuel can dissipate the heat from the slight current flow much easier than the air, the fuel would have to be really hot to turn the light on, in which case you will have a lot more problems, like no liquid fuel... Trampas -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Werner Schneider Subject: Re: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Werner Schneider" Interesting approach, would wonder what happens if you have a fuel injected engine with a return line (of "hot" fuel) back into the tanks. I'm using a optical device in my Glastar, works great and as it is LED it needs nearly no power!! http://www.ppavionics.com/LFL.htm Werner ----- Original Message ----- > When the thermistor is immersed in fuel, the fuel keeps the thermistor > cooled off, the resistance remains high and the indicator light bulb does > not light up. ________________________________ Message 8 _____________________________________ Time: 08:24:08 AM PST US From: "John Slade" Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "John Slade" > I'm using a optical device in my Glastar, works great and as it is LED it > needs nearly no power!! > > http://www.ppavionics.com/LFL.htm $405 per tank ??? there has to be a less expensive way. I'd be interested in learning more about that thermistor arrangement. John Slade ________________________________ Message 9 _____________________________________ Time: 08:37:01 AM PST US From: John R Subject: Re: AeroElectric-List: Transponder Main bus or Essential Bus --> AeroElectric-List message posted by: John R :-) Also, I liked your change of name from "Essential" bus to "Endurance" bus... if something is truly essential to continued flight, it should go on the battery bus... -John Robert L. Nuckolls, III wrote: >--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > See chapter 17 of the 'Connection or if you don't have the > book, download > > http://www.aeroelectric.com/articles/Rev9/ch17-9.pdf > > > > >>I agree on the essential bus. But you could just leave it on - it will >>consume very little power. It will be ready to use, especially in an >>emergency. >> >> > > Repeat after me, "We don't have "EMERGENCIES" in our airplanes, > only certified ships are designed and regulated to precipitate > EMERGENCIES". > > > > >> It only consumes non-trivial power when you need to transmit for >>a few seconds. >>Ernest Kells - RV-9A O235-N2C, Wood Prop >> 90 plus % Complete - seat kit arrived today >> >> >> >>>Essential bus - The transponder has an off switch so why sweat it. >>> >>> >>Bruce >> >> >>>www.glasair.org >>> >>> Which bus would you wire the Transponder to, and why? >>>Charlie Kuss >>> >>> >> >> > > Bob . . . > > -------------------------------------------- > ( Knowing about a thing is different than ) > ( understanding it. One can know a lot ) > ( and still understand nothing. ) > ( C.F. Kettering ) > -------------------------------------------- > > > > ________________________________ Message 10 ____________________________________ Time: 09:38:14 AM PST US From: Richard May Subject: AeroElectric-List: solar battery charger --> AeroElectric-List message posted by: Richard May I keep my plane in a T hanger that lacks electricity, I've purchased a couple of solar cell battery chargers from Harbor freight at $10 a piece andmounted them on the roof of my hanger. They work quite well, except that they give out after a few months of use. I connect one to the battery in my plane, and the other to the battery in my small tug to pull the airplane in and out of the hanger. I just recently read that they will discharge the battery at night or during cloudy days without a blocking diode. Does anyone know what type of diode to use for this purpose, and do I connect it to the positive or negative lead coming from the solar panel? Is there any type of device I could construct to prevent over-charging of batteries from Radio shack parts? ________________________________ Message 11 ____________________________________ Time: 10:51:37 AM PST US From: "Eric M. Jones" Subject: AeroElectric-List: solar battery charger --> AeroElectric-List message posted by: "Eric M. Jones" Subject: solar battery charger From: Richard May (ram45@comporium.net) >I've purchased a couple of solar cell battery chargers from Harbor freight at $10 a piece Make sure the cells put out a few volts more than the battery. You can put the cells in series just like batteries. >They work quite well, except that they give out after a few months of use. The Solar cells give out??? They should last forever. If the batteries give out they are probably suffering from never getting charged. >I just recently read that they will discharge the battery at night or during cloudy days >without a blocking diode. Does anyone know what type of diode to use for this purpose, and do >I connect it to the positive or negative lead coming from the solar panel? Use a 1N4001 to a 1N4007. Doesn't much matter. Use any "General Purpose" silicon diode. Attach it to the positive lead with the little silver band away from the solar cell. You can put it indoor going into the battery positive too. Little silver band goes towards the battery+. >Is there any type of device I could construct to prevent over-charging of >batteries from Radio shack parts? Yes. First buy a copy of "Forrest Mim's Engineer's Notebook" at Radio Shack . Then build a LM317 voltage regulator and adjust the output to whatever the battery's fully charged voltage should be. This won't do the fastest job but it will work well. You can forget about the diode if you take this route. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net "Kitty Hawk Centennial---first heavier-than-air flight that didn't immediately crash" ________________________________ Message 12 ____________________________________ Time: 11:13:31 AM PST US Subject: Re: AeroElectric-List: solar battery charger From: caspainhower@aep.com 10/17/2003 02:13:13 PM --> AeroElectric-List message posted by: caspainhower@aep.com Does anyone know what type of diode to use for this purpose, and do I connect it to the positive or negative lead coming from the solar panel? A schottky diode is most commonly used, they drop ~.2 volts instead of the ~.6 volts of a standard diode. As long as they are properly biased it shouldn't matter which lead they are in. Craig S. ________________________________ Message 13 ____________________________________ Time: 11:56:34 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Transponder Main bus or Essential Bus --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 11:42 AM 10/17/2003 -0500, you wrote: >--> AeroElectric-List message posted by: John R > >:-) > >Also, I liked your change of name from "Essential" bus to "Endurance" >bus... if something is truly essential to continued flight, it should go >on the battery bus... > >-John It's certainly an advantage to reduce parts count between an "essential" item and its power source to reduce probability that use of that item will not be lost. However, if having but one such "essential" device puts probability of comfortable completion of flight at risk, then one should have a BACKUP for it. If every item capable of ruining your day has a BACKUP, then all of a sudden, it is NOT ESSENTIAL. It changes the way you can look at system design and truly achieve a system that is both essential and emergency free. Bob . . . ________________________________ Message 14 ____________________________________ Time: 11:57:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Strobe wire? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > >Check www.strobesnmore.com . He can sell you the Nova power supply and >cable by the foot. If you're using only 2 strobe heads the XPak 604 will do >the job for you. I know a lot of folks are using the 904 but with only 2 >heads that power supply (904) reduces the power output. This is not the >case with the 604. If you're using more than 2 flash tubes it's a mute >point. Just thought I'd pass it along. >Bill >Glasair SIIS-FT Great data point Bill, thanks! Bob . . . ________________________________ Message 15 ____________________________________ Time: 11:59:04 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: 10856 Wandke --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > >Comments/Questions: Wonder if I can use #4 cable to hook up a firewall >mounted battery to a Sky Tec starter on a new )235N2C(lower >compression). Using an Odyssey 680 battery in a Murphy Rebel. Sure . . . #4 is quite adequate to this task when the battery and engine are close together. I will invite you to join us on the AeroElectric List to continue this and similar discussions. It's useful to share the information with as many folks as possible. A further benefit can be realized with membership on the list. There are lots of technically capable folks on the list who can offer suggestions too. You can join at . . . http://www.matronics.com/subscribe/ Well considered and technically elegant answers to all of your questions are waiting for you there. Also, check out the downloadable materials at http://www.aeroelectric.com Thanks! Bob . . . |---------------------------------------------------| | A lie can travel half way around the world while | | the truth is till putting on its shoes . . . | | -Mark Twain- | |---------------------------------------------------| ________________________________ Message 16 ____________________________________ Time: 12:00:36 PM PST US From: jerb Subject: Re: AeroElectric-List: Re: Strobe wire? --> AeroElectric-List message posted by: jerb Rather than Nyloflo - get some of the light weight 1/2" tubing used for Mister or drip irrigation systems. One point does it need to be flame retardant, if so it may not qualify for this application. jerb snip.... > Consider this instead. If you buy a Whelan kit, it will come > with the wire. How about running a conduit of Nyloflo or > similar tubing from root to tip now. When you get your kit > later, it will be easy to run the wires in. > > ================================ ________________________________ Message 17 ____________________________________ Time: 12:14:10 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 11:23 AM 10/17/2003 -0400, you wrote: >--> AeroElectric-List message posted by: "John Slade" > > > I'm using a optical device in my Glastar, works great and as it is LED it > > needs nearly no power!! > > > > http://www.ppavionics.com/LFL.htm > >$405 per tank ??? there has to be a less expensive way. I'd be interested in >learning more about that thermistor arrangement. Consider the Gemssenors p/n 143570 at: http://www.gemssensors.com/SpecTemplateStandard.asp?nProductGroupID=2 which can be had for $80 each and will drive a 40 ma lamp directly (plenty good for LED and you can find some 0.04A incandescent lamps too). Bob . . . ________________________________ Message 18 ____________________________________ Time: 12:23:43 PM PST US From: PTACKABURY@aol.com Subject: AeroElectric-List: Current Limiters --> AeroElectric-List message posted by: PTACKABURY@aol.com Bob: Help!! I am building a Lancair IV and am at the wire stringing stage. I have two 17 amp hour batteries and one 70 amp alternator. I have adopted a version of your Z-13 for the power distribution architecture, but can't figure out how many, where and what size current limiters I should use. Part of the problem is I can't read the diagrams in your book as the small print is fuzzy (and my eyes are on their sixth decade). So please tell me how to configure my current limiters. thanks and regards, paul ________________________________ Message 19 ____________________________________ Time: 01:40:09 PM PST US From: "Werner Schneider" Subject: Re: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Werner Schneider" What did you look at, one set is 115$ or 215$ a pair. Sure you can do it cheaper yourself, just you have to get two indicators with push to test (doing circuit test), two optical sensors , a circuit testing when the indicator fails etc. As you can see 4 wires are running between indicator and sensor for this purpose. Switch on current is a bit above 40ma, running on a bit over 20 ma for each sensor. As you've told you can make it cheaper, I found it value worth the money. It's up to everybody to decide by him/herself. And no I'm not in any way involved in PPA, just a happy customer =(;o) Werner ----- Original Message ----- From: "John Slade" Subject: RE: AeroElectric-List: thermistors for low fuel warning > --> AeroElectric-List message posted by: "John Slade" > > > I'm using a optical device in my Glastar, works great and as it is LED it > > needs nearly no power!! > > > > http://www.ppavionics.com/LFL.htm > > $405 per tank ??? there has to be a less expensive way. I'd be interested in > learning more about that thermistor arrangement. > John Slade > > ________________________________ Message 20 ____________________________________ Time: 01:41:30 PM PST US Subject: Re: AeroElectric-List: Current Limiters From: "Matt Prather" --> AeroElectric-List message posted by: "Matt Prather" Paul, You can get fresh copies of all of the diagrams in the appendix by downloading the following .pdf file: http://www.aeroelectric.com/articles/Rev10/z10.pdf Regards, Matt- VE N34RD > --> AeroElectric-List message posted by: PTACKABURY@aol.com > > Bob: Help!! I am building a Lancair IV and am at the wire stringing > stage. I have two 17 amp hour batteries and one 70 amp alternator. I > have adopted a version of your Z-13 for the power distribution > architecture, but can't figure out how many, where and what size > current limiters I should use. Part of the problem is I can't read the > diagrams in your book as the small print is fuzzy (and my eyes are on > their sixth decade). So please tell me how to configure my current > limiters. thanks and regards, paul > > ________________________________ Message 21 ____________________________________ Time: 01:47:30 PM PST US From: Joa Harrison Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: Joa Harrison Anybody ran across an auto part number for an auto fuel tank? Joa --------------------------------- ________________________________ Message 22 ____________________________________ Time: 03:25:26 PM PST US From: "Trampas" Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: "Trampas" Most of the 90's model Toyotas have them but you will most likely have to order the entire fuel sending unit, about $280. On the other hand I found that everything mustang sells the thermistor sensor for $32 www.everythingmustang.com Everything Mustang's website is down, I found the price through goggle's cache. http://216.239.51.104/search?q=cache:GvfTUJyGVUEJ:www.everythingmustang.com/ Merchant2/merchant.mv%3FScreen%3DCTGY%26Store_Code%3DEM%26Category_Code%3DTH ERME+low+fuel+light+thermistor&hl=en&ie=UTF-8 Trampas -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Joa Harrison Subject: RE: AeroElectric-List: thermistors for low fuel warning --> AeroElectric-List message posted by: Joa Harrison Anybody ran across an auto part number for an auto fuel tank? Joa --------------------------------- ________________________________ Message 23 ____________________________________ Time: 03:54:01 PM PST US From: Tom Brusehaver Subject: Re: AeroElectric-List: Transponder Main bus or Essential Bus --> AeroElectric-List message posted by: Tom Brusehaver Things could be better, with modern solid state transponders, but this is something that happened to me, with an older KT-76. During instrument training, we took off from FCM, in a Beech Sundowner. It was marginal VFR, and at 3000MSL there was an overcast. We were shooting my first approach for the day, VOR 11 at LVN, when approach called up and said they lost our transponder. Shocked my instructor said he'd look into it. He turned it off, then on, then pressed the CB, then fiddled and fiddled but the response light never came on. I went missed, called approach, and asked 'em anything on the transponder? They said nope. Can't well fly IFR in RADAR environment without a transponder, so we elected to head back to FCM (about 15min). During the trip, when the transponder was off, the ammeter showed almost no charge, with it on, a slight discharge. I cycled the master once, got about a 10AMP charge for about 2 seconds, then discharge. Could be the ammeter never really showed much of a discharge. Com/Nav Radios continued to work, but no-go on the transponder. We wouldn't have noticed the dead alternator, for a while, if approach wouldn't have told us they lost our transponder. Leave it on the essential buss, it could be a warning device if nothing else :-). Charlie Kuss wrote: > --> AeroElectric-List message posted by: Charlie Kuss > > Listers, > Which bus would you wire the Transponder to, and why? > Charlie Kuss > ________________________________ Message 24 ____________________________________ Time: 04:43:59 PM PST US From: jerb Subject: Re: AeroElectric-List: Need for relays? --> AeroElectric-List message posted by: jerb In most cases AC voltage/current rated switches normally will only carry a fraction of their AC rated current when used for DC current applications. The contacts are made of different material plus they use the zero crossing of the AC current to reduce contact burning/arcing when contacts are opened. Example a 5 Amp AC switch may only handle less than 100 mA of DC current. While some have improperly used them and gotten away with it for the time being, you'll never know when they will fail and fail prematurely. While AC rated switches may work fine for say for avionics switching for radios such as mike input or (logical level) feature control signals, any application carrying any amount of DC current more than 100 mA, use DC rated switches. They may cost a little more but lately I noticed there is getting to be less difference between the two. jerb At 04:30 PM 10/15/03 -0500, you wrote: >--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > >At 09:32 AM 10/15/2003 -0400, you wrote: > >--> AeroElectric-List message posted by: "Mark Banus" > > > >Bob, > > Just received plans for an engine install. It shows all switches with > > #22 wire going to relays (22 Relays). My understanding is that certain > > heavy loads (Pitot heat etc) need a relay as the switches can't handle > > the amps. But do I need relays for 3-10 amp circuits? More relays are > > more components to fail. I have looked at 125v 10 and 15 amp rocker > > switches from Digikey that look like they can handle the current. > > Pro/cons? Thanks\ > > Your switches will probably be just fine directly > switching the loads. See > http://www.aeroelectric.com/articles/swtchrat.pdf > > Bob . . . > > ________________________________ Message 25 ____________________________________ Time: 04:57:01 PM PST US From: Jerzy Krasinski Subject: AeroElectric-List: Bob, external power receptacle --> AeroElectric-List message posted by: Jerzy Krasinski Bob, I got a receptacle which is used commonly for connection to an external battery if internal battery is week. I was told that the receptacle is from a Cessna. I hoped for an easy installation but there are three prongs there. Two big ones are described "+" (the central one), and "-" (the side one). Unfortunately, there is a third one, smaller. No description there, but there are two ~1A diodes connected to it, able to conduct "from" the prong. I would like to make the receptacle compatible with battery carts at airports, so Cessna standard seems to be the right one. But how is the third prong connected? Is it used to drive a relay or something? I could not find anything on thet topic. I would appreciate your answer. Thank you, Jerzy Werner Schneider wrote: >--> AeroElectric-List message posted by: "Werner Schneider" > >Interesting approach, would wonder what happens if you have a fuel injected >engine with a return line (of "hot" fuel) back into the tanks. > >I'm using a optical device in my Glastar, works great and as it is LED it >needs nearly no power!! > >http://www.ppavionics.com/LFL.htm > >Werner > >----- Original Message ----- > > > >>When the thermistor is immersed in fuel, the fuel keeps the thermistor >>cooled off, the resistance remains high and the indicator light bulb does >>not light up. >> >> > > > > ________________________________ Message 26 ____________________________________ Time: 10:45:31 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Need for relays? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:48 PM 10/17/2003 -0700, you wrote: >--> AeroElectric-List message posted by: jerb > >In most cases AC voltage/current rated switches normally will only carry a >fraction of their AC rated current when used for DC current >applications. The contacts are made of different material plus they use >the zero crossing of the AC current to reduce contact burning/arcing when >contacts are opened. Example a 5 Amp AC switch may only handle less than >100 mA of DC current. Not so. Relays are only slightly different than toggle switches in that their contact spreading velocities are not enhanced with over-center springs . . . but the ratio is not so great that any 5A relay needs to be de0rated to 100 ma. See > While some have improperly used them and gotten away >with it for the time being, you'll never know when they will fail and fail >prematurely. While AC rated switches may work fine for say for avionics >switching for radios such as mike input or (logical level) feature control >signals, any application carrying any amount of DC current more than 100 >mA, use DC rated switches. They may cost a little more but lately I >noticed there is getting to be less difference between the two. . . . simply not supported by engineering data from switch and relay manufacturers. See http://www.aeroelectric.com/articles/swtchrat.pdf for an exploration of switches . . . relays are not terribly different. If any one can cite manufacturer's data sheets for any control product be it switch or relay that suggests an AC/DC de-rating ratio this severe, I'd like to get a copy of it. Much of what's being circulated as valid common knowledge has roots in the RVator article I cited in my piece on switch ratings. The author badly mis-interpreted the Microswitch data sheets. These seeds have grown into forests of electro-whizzy folklore. The question that started this thread was posted by a reader who was pondering an airframe wiring diagram suggested by an engine supplier wherein the panel was sprinkled with something on the order of 20 switches all driving relays used to actually control loads. There is simply no justification for doing this. It drives parts count up, cost up, reliability down, and offers little if any useful improvement in performance. This system was crafted with little or no practical knowledge of designing for the elegant solution. So far, I've only seen photos of installed equipment. I'm waiting to see the remainder of the documentation before we attempt to comb the rats and tangles out of this badly over-built system. Bob . . . ________________________________ Message 27 ____________________________________ Time: 10:47:08 PM PST US From: kempthornes Subject: Re: AeroElectric-List: Need for relays? --> AeroElectric-List message posted by: kempthornes At 06:48 PM 10/17/2003 -0700, you wrote: >--> AeroElectric-List message posted by: jerb > >In most cases AC voltage/current rated switches normally will only carry a >fraction of their AC rated current when used for DC current >applications. I've been turning my electric fuel pump on and off with a micro toggle switch rated for AC with no explosions yet. Any day now tho, eh? >The contacts are made of different material plus they use >the zero crossing of the AC current to reduce contact burning/arcing My wife has so much trouble catching that brief little zero crossing that she just leaves lights on all over the house. K. H. (Hal) Kempthorne RV6-a N7HK - Three trips to OSH now. PRB (El Paso de Robles, CA)