---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 10/16/10: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:09 AM - Re: Catch diode location (Eric M. Jones) 2. 07:19 AM - Re: Re: Catch diode location (Robert L. Nuckolls, III) 3. 07:31 AM - Re: Re: Strobe Noise Low Voltage? (Robert L. Nuckolls, III) 4. 07:41 AM - Re: Re: Trim Tab Indicator (Robert L. Nuckolls, III) 5. 08:14 AM - Re: Catch diode location (jonlaury) 6. 08:42 AM - Re: Catch diode location (Eric M. Jones) 7. 09:56 AM - Re: Re: Catch diode location (Robert L. Nuckolls, III) 8. 05:54 PM - Laptop supply for your car/airplane (Robert L. Nuckolls, III) 9. 06:24 PM - Re: Laptop supply for your car/airplane (Bill Boyd) 10. 07:52 PM - Re: Laptop supply for your car/airplane (Joe Dubner) 11. 08:25 PM - Re: Laptop supply for your car/airplane (Bill Boyd) ________________________________ Message 1 _____________________________________ Time: 06:09:18 AM PST US Subject: AeroElectric-List: Re: Catch diode location From: "Eric M. Jones" Modern relay and contactor manufacturers recommend using bidirectional Zeners for coil suppression, NOT diodes. Mechanical relays and contactors depend upon magnetism generated by an electric current running through a wire coil. When the current stops, the magnetic field collapses. But the relay does not know the difference between a wire coil moving in a magnetic field (as in a generator) or a magnetic field moving in a wire coil (as in a collapsing magnetic field). Thus a large voltage1000V to 1500V typicallyis induced in the coil. This current goes the same direction the original current didso it slows the contact openingallowing arcing, chatter, bouncing, contact welding and even re-closure. http://www.periheliondesign.com/suppressors/SnapJack.pdf Or buy your own, I recommend P6KE18CA for general purposes. Another advantage is you can't put them in the wrong direction. They are symmetrical. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=315939#315939 ________________________________ Message 2 _____________________________________ Time: 07:19:05 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Catch diode location At 08:04 AM 10/16/2010, you wrote: > >Modern relay and contactor manufacturers recommend using >bidirectional Zeners for coil suppression, NOT diodes. . . . an assertion that appears to be based upon a paper published by Tyco authors that in-expertly speak to issues not relevant to the manner in which we use diodes on our relays and contactors. Furhter, they made mis-interpreted the significance of their own data. This was examined at length some years ago Eric and you offered no evidence or analysis contrary to the explanations I demonstrated and published. If you have some personally developed rationale for contradicting what I wrote, please bring it forward. Bob . . . ________________________________ Message 3 _____________________________________ Time: 07:31:06 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Strobe Noise Low Voltage? At 02:07 PM 10/15/2010, you wrote: > > >I'm not intentionally testing it that low, it's just that I'm not >flying and I'm only running the engine every couple of weeks. I've >spent hours upon hours trying to find my strobe noise issue. In the >mean time, I'm realizing that I haven't charged the battery and all >the while my strobes are draining battery. > >Last night it just occured to me that my problem might just be >related to that. And, I dont care if there is strobe noise at 10V >as long as that is the issue and not a poor ground or something similar. This thread brings up several thoughts from the depths of past experiences . . . The noise levels you may be hearing while parked in the hangar just may be too small to be significant with the engine running . . . or with the aircraft in flight. I recall being summoned to the King Air line many moons ago to help with some blower motor noise that was reported audible in the cockpit intercom system. When I got there, I discovered that the volume controls were all maxed out and yes, you could hear some motor noise that went away when the blower breaker was pulled. After repositioning the controls to levels typical of normal flight conditions, I asked if they thought the noise might be objectionable or even perceptible over normal cockpit noises. They checked a few more airplanes and then talked to some pilots and decided that it was a non-problem. This scenario has repeated many times. No system is totally free of extraneous noises. The benchmark for usefulness is quantified by Signal to Noise Ratio. Make sure your observations are not being made under extraordinary measurement conditions. It's also possible that a power supply becomes extra- noisy under low voltage conditions. Suggest you invest in a nice 13.8v, switchmode power supply to power up systems on the ground. There's a boat load of nice supplies on Ebay right now. http://tinyurl.com/2fgxrrz Bob . . . ________________________________ Message 4 _____________________________________ Time: 07:41:54 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: RE: Trim Tab Indicator At 03:21 PM 10/15/2010, you wrote: Bob: A couple of questions on your miniature meter movements; How does one change the scale? I lay out a new scale plate in AutoCAD. For b/w plates, I print the new scale on full-sheet Avery label material (sticky back w/peel-off cover) and a laser printer. For color I use matt photo paper and color printer. New scales are attached to the back side of the existing scale plate. Is it difficult to get the face plate off? I don't take off the old one, just put the new one over the old one or on the back side of the existing plate. Would just a piece of paper with the scale you want printed on it be sufficient for the scale or would you have to use a special paper? I presume the meter is a 0 to full scale operation. Is there any easy way to make it a center zero meter such that you could use it for a 30 0 30 ammeter? It depends on the pointer's zero-springs. SOMETIMES . . . the rear spring has enough adjustment travel to allow moving the zero- current pointer position to the center of the movement's travel. I've not tried it with these devices that I can recall. Also, I was unable to find the product listing for the price of the miniature meter on your webpage. How much is the meter? The instruments I hypothesized in the posting do not exist. I would have to do some 'real' scale stickers and modify some new instruments. I have a load-meter that is already in stock. https://matronics.com/aeroelectric/Catalog/AEC/9007/9007.html The instrument with a shunt is $70. To do a one-of-a-kind would be a bit more. Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:14:33 AM PST US Subject: AeroElectric-List: Re: Catch diode location From: "jonlaury" Eric and Bob McC, Thank you both for spelling it all out for me. I like the bi-di- zener solution because it's idiot proof and perfect for people like me that have just enough electronic knowledge to be dangerous. Eric, your schematics of all the different scenarios are priceless. With all the other sorts of subjective decisions involved in building my plane, it's REALLY a luxury to have an experienced person say "Here, do it this way". Contributions, like yours, to this forum, really make it sing. John Read this topic online here: http://forums.matronics.com/viewtopic.php?p=315953#315953 ________________________________ Message 6 _____________________________________ Time: 08:42:27 AM PST US Subject: AeroElectric-List: Re: Catch diode location From: "Eric M. Jones" The application of relay coil suppression with DC relays www.ciitechnologies.com/appnotes/app_pdfs/13c3311.pdf Coil Suppression Can Reduce Relay Life relays.tycoelectronics.com/appnotes/app_pdfs/13c3264.pdf Coil Suppression www.leachintl2.com/english/english2/vol6/properties/how7.htm Coil Suppression Techniques: www.newark.com/pdfs/techarticles/crydom/May2010_SolidStatements.pdf You want more? Using diodes for coil suppression is Soooooooooooo 1900's Bob. Come on board to the next century. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=315957#315957 ________________________________ Message 7 _____________________________________ Time: 09:56:36 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Catch diode location At 10:39 AM 10/16/2010, you wrote: > > >Using diodes for coil suppression is Soooooooooooo 1900's Bob. Come >on board to the next century. Eric. Those papers were crafted for exploring the tradeoffs for relays designed to operate under rated loads for tens to hundreds of thousands of cycles. And yes, SOME of the studies show a benefit for not clamping the recoil spike at near zero volts with a diode and instead allowing it to rise to some level determined by a zener. THIS forum of discussion is not about crafting electrical systems for military or space-grade vehicles. On average, the GA light aircraft flies 50 hours a year. OBAM aircraft as a class are probably higher. So let us say after 20 years, the airplane MIGHT have 3000 hours on it. How many THOUSANDS of operations might any given relay or contactor see on such a vehicle? Certainly not hundreds of thousands nor even tens of thousands. How many of our relays are loaded such that they switch rated loads for every cycle? Adding super-suppression to a relay might produce a 10-20% improvement in laboratory life tests running at rated loads . . . probably NO improvement for lightly loaded or dry-circuit switching. The point is my friend that there is no value to be secured for NOT buying coil suppression devices at Radio Shack as opposed to the "ideal" device ordered in from remote sources for more money and time. You have taken a few facts and morphed them into a level of significance that is simply not applicable to the customers you and I serve for the airplanes they are building. The next century? Hammers have been around for thousands of years . . . but that does not mean that the task of driving a nail is not well served by keeping a few hammers in my toolbox. The point of my writing for this audience is to tailor a suggestion for adequate performance at the least cost and time . . . i.e. the elegant solution. The solutions may or may not comport with findings produced in a laboratory that will never study what we do on the OBAM GA aircraft. Bob . . . ________________________________ Message 8 _____________________________________ Time: 05:54:04 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Laptop supply for your car/airplane I just ran across this item on Ebay: http://tinyurl.com/2cyx7c7 With an input from your 14v bus, it can be set up to provide the typical 18-20 volts needed by many laptops. Bob . . . ________________________________ Message 9 _____________________________________ Time: 06:24:15 PM PST US Subject: Re: AeroElectric-List: Laptop supply for your car/airplane From: Bill Boyd Sounds like it may be useful for powering portable HF gear (the common 10 watt rice boxes) from Li-poly or Li-metal cells that don't readily supply 12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might still be better efficiency than a dropping regulator on a 16v pack... -Bill Boyd On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > I just ran across this item on Ebay: > > * http://tinyurl.com/2cyx7c7* > > With an input from your 14v bus, it can be set up > to provide the typical 18-20 volts needed by many > laptops. > > > Bob . . . > > * > > * > > ________________________________ Message 10 ____________________________________ Time: 07:52:49 PM PST US From: Joe Dubner Subject: Re: AeroElectric-List: Laptop supply for your car/airplane Sounds like it might even /be/ HF gear :-) That single-sided PCB with minimal filtering (judging only by the pictures -- see http://tinyurl.com/2943gjk) probably radiates switching transient energy through VHF and beyond. Of course if used with a laptop PC as per Bob's original suggestion, this point may be mute because the laptop has it's own issues. But I'd be leery about using it around receiving equipment in an aircraft (or elsewhere). My $.02 -- YMMV. -- Joe Independence, OR http://www.mail2600.com/position http://www.mail2600.com/cgi-bin/webcam.cgi Bill Boyd wrote: > Sounds like it may be useful for powering portable HF gear (the common 10 > watt rice boxes) from Li-poly or Li-metal cells that don't readily supply > 12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might > still be better efficiency than a dropping regulator on a 16v pack... > > -Bill Boyd > > On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > >> I just ran across this item on Ebay: >> >> * http://tinyurl.com/2cyx7c7* >> >> With an input from your 14v bus, it can be set up >> to provide the typical 18-20 volts needed by many >> laptops. >> >> >> Bob . . . >> >> * >> >> * >> >> > ________________________________ Message 11 ____________________________________ Time: 08:25:56 PM PST US Subject: Re: AeroElectric-List: Laptop supply for your car/airplane From: Bill Boyd Looks to be in a metal enclosure, though. On Sat, Oct 16, 2010 at 10:49 PM, Joe Dubner wrote: > > Sounds like it might even /be/ HF gear :-) > > That single-sided PCB with minimal filtering (judging only by the pictures > -- see http://tinyurl.com/2943gjk) probably radiates switching transient > energy through VHF and beyond. > > Of course if used with a laptop PC as per Bob's original suggestion, this > point may be mute because the laptop has it's own issues. But I'd be leery > about using it around receiving equipment in an aircraft (or elsewhere). > > My $.02 -- YMMV. > > -- > Joe > Independence, OR > http://www.mail2600.com/position > http://www.mail2600.com/cgi-bin/webcam.cgi > > > Bill Boyd wrote: > >> Sounds like it may be useful for powering portable HF gear (the common 10 >> watt rice boxes) from Li-poly or Li-metal cells that don't readily supply >> 12.6-13.8v ganged as batteries. 85% efficiency is not stellar, but might >> still be better efficiency than a dropping regulator on a 16v pack... >> >> -Bill Boyd >> >> On Sat, Oct 16, 2010 at 8:51 PM, Robert L. Nuckolls, III < >> nuckolls.bob@aeroelectric.com> wrote: >> >> I just ran across this item on Ebay: >>> >>> * http://tinyurl.com/2cyx7c7* >>> >>> With an input from your 14v bus, it can be set up >>> to provide the typical 18-20 volts needed by many >>> laptops. >>> >>> >>> Bob . . . >>> >>> * >>> >>> * >>> >>> >>> >> > > ------------------------------------------------------------------------------------- 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.