---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 08/02/12: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:28 AM - Re: PM Alternator filter Capacitor - best practices (Robert L. Nuckolls, III) 2. 05:28 AM - Re: PM Alternator filter Capacitor - best practices (Robert L. Nuckolls, III) 3. 08:56 AM - Re: PM Alternator filter Capacitor - best practices (Tundra10) 4. 04:08 PM - Re: PM Alternator filter Capacitor - best practices (John Loram) 5. 08:15 PM - Re: Re: PM Alternator filter Capacitor - best practices (Robert L. Nuckolls, III) 6. 09:28 PM - Extending thermocouple leads (Radioflyer) ________________________________ Message 1 _____________________________________ Time: 05:28:20 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: PM Alternator filter Capacitor - best practices At 10:18 PM 8/1/2012, you wrote: So we're not trying to control the bandwidth of the regulator loop with the cap? Does the battery do that? Guess I don't really know what the frequency response of a lead-acid battery is. Probably dependent on the state of charge and the condition of the battery. And the load varies all over the place, both real and imaginary components.... What would it look like with and without the cap if the battery were out of the loop? ... Scary! http://tinyurl.com/bqa6q9p Finely tuned loop dynamics with these regulators is wishful thinking. Here's an exemplar schematic for a PM regulator: http://tinyurl.com/bwomjjz I split out the two functions (regulation and warning light) http://tinyurl.com/c8usyw2 http://tinyurl.com/c6doa97 As you can see in the v-reg schematic, there are no reactive components that would shape closed-loop response. A battery is a very poor 'filter' . . . it delivers energy at 12.5 and below . . . accepts energy at 13.8 and above. That's about 1.3 volts of span where the battery is dynamically 'unhooked'. It stands to reason that the capacitor would have the greatest effect when the alternator set point was too low (under 14.5) and the system was lightly loaded. I'm running 3 phase (old Jab 3300). Interesting. I think your regulator is still quite similar . . . it just adds another diode/scr pair. Once I get this thing fired up I'll run some tests and let you know what happens... I have a fast switching, dynamic load bank I built for tests at HBC some years back. It would be interesting to use it along with a data acquisition system on the test bench to explore the closed loop response of these systems. Just thinking out loud, -john- p.s. ran into a message the other day that you wrote back in 2007. Said you worked for H.L Yoh as a civilian instructor in the early 60's... Same here! At the Naval ETA school on Treasure Island. Wasn't that fun. I learned more electronics in six months instructing those kids than four years of collage! You got that right! I was teaching in the top 4 weeks of a 26 week school at Great Lakes. I went to work on a Friday and they handed me a syllabus for my first section of students along with a copy of "the bible", Termnan's Electrical Engineering Handbook http://tinyurl.com/cbvvjx9 and said, "you get your first class of 20 next Monday." As long as I stayed a day ahead of the class . . . things went well . . . and yes, a lot of fun. After four or so passes through the class materials and figuring out a half dozen ways to explain each concept, it sorta creeps into your DNA. There's no better way to learn something than to be chartered to teach it. Do you have access to a fast data acquisition system that you could hook to your bus for some hard data gathering? I've used cousins to this critter . . . http://tinyurl.com/3jtrxx4 on several tasks at HBC with great results. Being able to jump on an airplane and get hard data in flight without having to involve a dozen folks from the instrumentation lab was a powerful tool. You might consider getting one of these and use it to graph some of the performance qualities of your system. It would be a great augmentation of my ripple studies. Bob . . . ________________________________ Message 2 _____________________________________ Time: 05:28:20 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: PM Alternator filter Capacitor - best practices At 10:18 PM 8/1/2012, you wrote: So we're not trying to control the bandwidth of the regulator loop with the cap? Does the battery do that? Guess I don't really know what the frequency response of a lead-acid battery is. Probably dependent on the state of charge and the condition of the battery. And the load varies all over the place, both real and imaginary components.... What would it look like with and without the cap if the battery were out of the loop? ... Scary! http://tinyurl.com/bqa6q9p Finely tuned loop dynamics with these regulators is wishful thinking. Here's an exemplar schematic for a PM regulator: http://tinyurl.com/bwomjjz I split out the two functions (regulation and warning light) http://tinyurl.com/c8usyw2 http://tinyurl.com/c6doa97 As you can see in the v-reg schematic, there are no reactive components that would shape closed-loop response. A battery is a very poor 'filter' . . . it delivers energy at 12.5 and below . . . accepts energy at 13.8 and above. That's about 1.3 volts of span where the battery is dynamically 'unhooked'. It stands to reason that the capacitor would have the greatest effect when the alternator set point was too low (under 14.5) and the system was lightly loaded. I'm running 3 phase (old Jab 3300). Interesting. I think your regulator is still quite similar . . . it just adds another diode/scr pair. Once I get this thing fired up I'll run some tests and let you know what happens... I have a fast switching, dynamic load bank I built for tests at HBC some years back. It would be interesting to use it along with a data acquisition system on the test bench to explore the closed loop response of these systems. Just thinking out loud, -john- p.s. ran into a message the other day that you wrote back in 2007. Said you worked for H.L Yoh as a civilian instructor in the early 60's... Same here! At the Naval ETA school on Treasure Island. Wasn't that fun. I learned more electronics in six months instructing those kids than four years of collage! You got that right! I was teaching in the top 4 weeks of a 26 week school at Great Lakes. I went to work on a Friday and they handed me a syllabus for my first section of students along with a copy of "the bible", Termnan's Electrical Engineering Handbook http://tinyurl.com/cbvvjx9 and said, "you get your first class of 20 next Monday." As long as I stayed a day ahead of the class . . . things went well . . . and yes, a lot of fun. After four or so passes through the class materials and figuring out a half dozen ways to explain each concept, it sorta creeps into your DNA. There's no better way to learn something than to be chartered to teach it. Do you have access to a fast data acquisition system that you could hook to your bus for some hard data gathering? I've used cousins to this critter . . . http://tinyurl.com/3jtrxx4 on several tasks at HBC with great results. Being able to jump on an airplane and get hard data in flight without having to involve a dozen folks from the instrumentation lab was a powerful tool. You might consider getting one of these and use it to graph some of the performance qualities of your system. It would be a great augmentation of my ripple studies. Bob . . . ________________________________ Message 3 _____________________________________ Time: 08:56:18 AM PST US Subject: AeroElectric-List: Re: PM Alternator filter Capacitor - best practices From: "Tundra10" So should the capacitor and 1K resistor be deleted from Z13/8 ? Note 20 indicates the purpose of the capacitor is to smooth the voltage if the battery is offline. However, there is no intentional way of disconnecting the battery, and there are very few failures that could result in the battery being disconnected while the SD-8 still remains connected to the battery bus. In Z13/8 the SD-8 is only turned on in the event of a main alternator failure. Maybe in this circumstance, a little noise in the audio is not significant to the completion of the flight (assuming the capacitor actually helps in a given installation). Jeff Page Dream Aircraft Tundra #10 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=379872#379872 ________________________________ Message 4 _____________________________________ Time: 04:08:57 PM PST US From: "John Loram" Subject: RE: AeroElectric-List: PM Alternator filter Capacitor - best practices Thank you for the schematics. Most instructive! > > p.s. ran into a message the other day that you wrote back in 2007. > Said you worked for H.L Yoh as a civilian instructor in the > early 60's... Same here! At the Naval ETA school on Treasure > Island. Wasn't that fun. I learned more electronics in six > months instructing those kids than four years of collage! > > You got that right! I was teaching in the > top 4 weeks of a 26 week school at Great > Lakes. I went to work on a Friday and they > handed me a syllabus for my first section > of students along with a copy of "the bible", > Termnan's Electrical Engineering Handbook > > http://tinyurl.com/cbvvjx9 And thank you for Villard's Memoir. I loved reading every bit of it! Like every self-respecting EE I have kept my copy of Terman. > > and said, "you get your first class of 20 > next Monday." As long as I stayed a day ahead > of the class . . . things went well . . . > and yes, a lot of fun. After four or > so passes through the class materials and > figuring out a half dozen ways to explain each > concept, it sorta creeps into your DNA. There's > no better way to learn something than to > be chartered to teach it. > And in every other class you'd get one 'ringer'. A kid fresh out of engineering school who would nail you to the chalk board at the slightest slip-up!!! You either got those guys on your side right away or you were in for some tough sledding! > Do you have access to a fast data acquisition > system that you could hook to your bus for > some hard data gathering? > > I've used cousins to this critter . . . > > http://tinyurl.com/3jtrxx4 I have a couple of these first generation DI-148Us. It will run at 11 KHz sampling rate on one channel. Tell me more about your dynamic load bank. Sounds like just the ticket. >... > You might consider getting one of these > and use it to graph some of the performance > qualities of your system. It would be a great > augmentation of my ripple studies. > > > Bob . . . > > I'd be happy to contribute! I'm probably a month away from first start and another month coming down off the high!!, -john- ________________________________ Message 5 _____________________________________ Time: 08:15:14 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: PM Alternator filter Capacitor - best practices At 10:55 AM 8/2/2012, you wrote: So should the capacitor and 1K resistor be deleted from Z13/8 ? Don't delete anything. We're having a discussion about the notion that data gathered on an SD-8 with a 'scope about 10 years ago doesn't confirm legacy beliefs about what a capacitor across a power supply does for us. This capacitor MAY have some value in fast, low energy transient mitigation and/or regulation dynamics. John and I will continue to ponder "out loud on the List" but don't take any hypothesis as cause to rise up and evict your capacitor. The capacitor AND 1K resistor are also participants in the self excitation system. Note 20 indicates the purpose of the capacitor is to smooth the voltage if the battery is offline. However, there is no intentional way of disconnecting the battery, and there are very few failures that could result in the battery being disconnected while the SD-8 still remains connected to the battery bus. In Z13/8 the SD-8 is only turned on in the event of a main alternator failure. Maybe in this circumstance, a little noise in the audio is not significant to the completion of the flight (assuming the capacitor actually helps in a given installation). Good questions/suppositions all . . . we'll endeavor to sort it out with greater clarity. Bob . . . ________________________________ Message 6 _____________________________________ Time: 09:28:54 PM PST US Subject: AeroElectric-List: Extending thermocouple leads From: "Radioflyer" I think I understand how to do things right with thermocouples, but want to make sure. I have a set of (GRT/EIS) J- type, CHT bayonet thermocouples. The 2 foot leads are terminated from the factory in what I believe to be standard spade terminals. I need to lengthen these leads about 12 feet to reach my MGL Avionics quad CHT display instrument. So I plan to get some J-type wire, crimp on some mating spade terminals and similarly terminate the other end very close to the instrument. (One set of spades will be in the hot engine compartment and the spades on the other end of the extension will be in the cabin.) My understanding is that the parasitic couples at the spade terminals will be cancelled out, so I should get accurate temp readings at the instrument. Correct? Is it worth the trouble to search for stranded J-wire or is solid good enough? --Jose Read this topic online here: http://forums.matronics.com/viewtopic.php?p=379921#379921 ------------------------------------------------------------------------------------- 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.