---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 05/07/06: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:02 AM - Re: SD-8 PM Alternator (Robert L. Nuckolls, III) 2. 10:47 AM - Iso Amp - digikey substitutions (Mitchell Faatz) 3. 12:12 PM - Controlling three things with a 2-10 switch (Mitchell Faatz) 4. 01:18 PM - Re: Controlling three things with a 2-10 switch (Robert L. Nuckolls, III) 5. 04:18 PM - Re: Charging system failure (DAVID REEL) 6. 06:32 PM - Squitter.... (Jim Baker) 7. 07:41 PM - crimp dies (Robert G. Wright) 8. 08:19 PM - Re: SD-8 PM Alternator (J. Mcculley) 9. 08:46 PM - Re: Re: Charging system failure (Brian Lloyd) ________________________________ Message 1 _____________________________________ Time: 07:02:35 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: SD-8 PM Alternator --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 11:52 PM 5/6/2006 -0400, you wrote: >--> AeroElectric-List message posted by: "J. Mcculley" > > >'Lectric Bob, > >On 4/22/06, you responded to my earlier report of a way to assure >bringing the SD-8 PM alternator on line without benefit of a battery >source of excitation. My finding that as little as one volt charge on a >capacitor was adequate to awaken the SD-8 apparently suggested to you >that there might be an even simpler way to modify the SD-8 regulator to >accomplish independence of the PM alternator from a battery source of >start-up voltage. Your proposed design was as follows: > > > >I am happy to report that I implemented your concept and conducted >successful ground testing today of the SD-8 installation on my Lycoming >180 HP Tailwind. > >In order to achieve the desired range of voltage across the capacitor >when BOTH the alternator is OFF LINE and the MASTER switch is OFF, I >found it necessary to increase the suggested 10k ohm resistor from >ground to the pair of diodes to a value of 15k, and to increase the 1k >ohm resistor across the capacitor to 3k ohm. What was the voltage with the pair of 1K resistors? I would expect it to be on the order of 2-6 volts at 2000 rpm with the alternator switch off. >In this configuration, the voltage across the capacitor slowly rises to >0.6 volts within a 3 minute period after engine start while warming up >at 1100 Engine RPM (1430 alternator RPM). This is insufficient to bring >the alternator on line if the Alternator switch is then turned on. Hmmm . . . we would expect that. The target voltage would be much higher and I would adjust the paralleling resistor upward from 1K to adjust for desired value. >However, as the engine RPM is advanced to the range of 1700-1800 for mag >check, the alternator is now at 2210-2340 RPM with capacitor voltage >slightly above 0.6 v and if the alternator switch is now turned on the >alternator comes alive to produce an unloaded buss voltage of slightly >over 12 V. Yeah, this would represent the minimum speed for regulation (actually a tad low 'cause it's still not up to the regulator setpoint) but insufficient rpm to deliver significant energy. The fact that it 'came alive' is the significant point. > This unloaded buss voltage continues to rise with RPM to a >maximum of 14.42 V at engine rated 2700 RPM (alternator at 3510 RPM). As >buss load is added, the regulator maintains 14.29 V until enough load is >added to begin dropping the voltage in keeping with the alternator >design current limits. With the Master switch still OFF, the buss >voltage responds to the electrical load versus RPM in a predictable >manner. Even if the RPM/load combination is carried to an extreme that >produces buss voltage down to as little as 5 V, the alternator stays >activated and comes back up in voltage to no higher than 14.42 if the >load/RPM combination is re-adjusted. Yup, as long as the output is kept above the wake-up voltage, I would not expect it to go back to sleep. We're getting close to a solution here. Find a value for the resistor in parallel with the capacitor that gives us a wake-up voltage of 2-3 volts at 2200 rpm. The only time you would NEED the system to come up is in flight and at 2200 rpm or higher. What we're looking for is the right value for parallel R that gives us the 2-3 volts at 2200. >I suspect the system would respond differently with a smaller capacitor >than the 56K mf unit that I adapted from my previous set-up, but I did >not observe any undesirable features, and at this preliminary stage I >believe the overall concept produces a fully automatic solution to >eliminate the fear that a PM alternator could fail to come on line in >the absence of a voltage source such as the ship's battery. Yes. The fat electrolytic will take a few seconds to come up to a static value but in this came, time is not critical. >Please recognize that the above data during operation of the SD-8 just >after engine start-up is not the condition of interest in normal >operation. The engine (and alternator) would more likely be at higher >RPM during cruise flight when the buss voltage might be lost while the >SD-8 is not on line. In this situation,the alternator RPM and available >voltage across the capacitor would already be high enough to immediately >bring the alternator on line by simply turning the alternator switch on. >I will soon verify this on an upcoming flight. Okay. What you could do is bring a wire into the cockpit off the filter capacitor. Put a fuse in series with it at the capacitor end. You can fiddle with the load resistor value and monitor voltage on the lead from the operator's seat. I appreciate your time and interest in helping us craft and conduct the experiment. Bob . . . ________________________________ Message 2 _____________________________________ Time: 10:47:48 AM PST US From: Mitchell Faatz Subject: AeroElectric-List: Iso Amp - digikey substitutions --> AeroElectric-List message posted by: Mitchell Faatz Just in case this helps somebody some day... I'm building the Audio Iso Amp from Bob's plans (Thanks Bob!) and Digikey no longer carries any of the capacitor call-outs, so here are what I think are valid substitutions with in-stock part numbers: 399-1429 becomes 399-3529-ND 399-1395 becomes 399-3586-ND 399-2127 becomes P4923-ND 399-1403 becomes 399-3563-ND Also, an adjustable trim pot for 103-107 (Note 6) might use part number 490-2694-ND (Trimpot 1K 1 turn top adj). Mitch Faatz RV-6A Finish Kit Auburn, CA ________________________________ Message 3 _____________________________________ Time: 12:12:09 PM PST US From: Mitchell Faatz Subject: AeroElectric-List: Controlling three things with a 2-10 switch --> AeroElectric-List message posted by: Mitchell Faatz I'm using a 2-10 to control both Nav lights (middle position) and Nav + Strobes (up position) like figure 11-18 in Bob's book. I also want to turn on the cockpit/map lights when the Nav lights are on. Is there anyway (using relays or something) to do both? I'm not sure I have room for an identical 4-10 (four pole) switch. The Nav circuit is 10 amp, while the Cabin/Map light circuit is 5 amp. Thanks Mitch Faatz RV-6A Finish Kit Auburn, CA ________________________________ Message 4 _____________________________________ Time: 01:18:17 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Controlling three things with a 2-10 switch --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 12:04 PM 5/7/2006 -0700, you wrote: >--> AeroElectric-List message posted by: Mitchell Faatz > >I'm using a 2-10 to control both Nav lights (middle position) and Nav + >Strobes (up position) like figure 11-18 in Bob's book. I also want to >turn on the cockpit/map lights when the Nav lights are on. Is there >anyway (using relays or something) to do both? >I'm not sure I have room for an identical 4-10 (four pole) switch. The >Nav circuit is 10 amp, while the Cabin/Map light circuit is 5 amp. May I suggest that you leave these lights run all the time? Just dim them to minimum when not in use? Lamps will last just about forever at a voltage just above that required for just-visible light output. This simplifies your system and avoids having a blown nav-light fuse put your cockpit in the dark also. Further, some minimal panel lighting should run from the e-bus . . . or perhaps from their own batteries. I've seen some nifty LED panel floods that run from internally L-Ion batteries good for hundreds of hours of run time. Bob . . . --------------------------------------------------------- < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > --------------------------------------------------------- ________________________________ Message 5 _____________________________________ Time: 04:18:00 PM PST US From: "DAVID REEL" Subject: AeroElectric-List: Re: Charging system failure --> AeroElectric-List message posted by: "DAVID REEL" After Bob and Brian put me on to the stability issue, I replaced the fuse in the alternator field supply circuit with a fuse link and replaced the regulator with an adjustable Vans regulator. Then I set the bus voltage to 13.8 with the engine at 1000rpm and no loads but battery charging & the master contactor. Next I added the Whelen strobes & got instability of +2 tenths of a volt. As I was seeing +3 tenths with the fuse, I believe replacing the fuse eliminated one third of the resistance in the circuit outside the regulator. Then I added nav lights. The bus voltage went up to 13.95. Then I added my landing light & the bus went up further to 14.06. In both cases, the strobe variation appeared to greatly decrease or disappear. Since my nav load is 8.5 amps and my landing light load is 4.6 amps, it appears that my bus to regulator input resistance is now in the neighborhood of .018 to .02 ohms. Now here come the big questions for Bob or Brian or anyone else: Is .02 ohms small enough for reasonable stability? How much typically comes from a circuit breaker? At cruise rpm where field circuit amperage will presumably be less, will stability increase due to decreased voltage drop? Or will stability decrease because the smaller current requires more precise manipulation? What happens to voltage in the millisecond range which I'd need an oscilloscope to see? Will it be much less stable than what I'm seeing on my digital voltmeter? I should be able to fly again Tuesday & I guess, should I continue to get OV trips, I could always fly with nav lights on & see if that solved the problem. Ugh! Dave Reel - RV8A ________________________________ Message 6 _____________________________________ Time: 06:32:02 PM PST US From: "Jim Baker" Subject: AeroElectric-List: Squitter.... --> AeroElectric-List message posted by: "Jim Baker" OK. I give up. I know what this means in terms of unsolicited transmission of data (as in Mode S). Anyone know its origin or is this an amalgam of two or more words..... Jim Baker 580.788.2779 Elmore City, OK ________________________________ Message 7 _____________________________________ Time: 07:41:06 PM PST US From: "Robert G. Wright" Subject: AeroElectric-List: crimp dies --> AeroElectric-List message posted by: "Robert G. Wright" Bob et.al., Regarding http://aeroelectric.com/articles/bnccrimp.pdf, did you write this article based off of RG-400? What size dies will I need for RG-58 and -400? I've got a multi-size die from eclipse that has .324, .255, .213, .100, and .068 cavities. Rob Wright RV-10 #392 ________________________________ Message 8 _____________________________________ Time: 08:19:15 PM PST US From: "J. Mcculley" Subject: Re: AeroElectric-List: SD-8 PM Alternator --> AeroElectric-List message posted by: "J. Mcculley" Bob, Hope the following responses to your questions will be helpful. My apologies for not having more detailed test data. A well controlled bench test would be far better than my preliminary ground run-up testing on the engine installation! That is a difficult environment. (SNIP)In order to achieve the desired range of voltage across the capacitor when BOTH the alternator is OFF LINE and the MASTER switch is OFF, I found it necessary to increase the suggested 10k ohm resistor from ground to the pair of diodes to a value of 15k, and to increase the 1k resistor across the capacitor to 3K. (SNIP) | What was the voltage with the pair of 1K resistors? I would expect | it to be on the order of 2-6 volts at 2000 rpm with the alternator | switch off. I don't have that answer. Your schematic showed a 1k resistor at both the diodes to ground as well as across the capacitor, but you commented that you suspected the series resistor might be as large as 3k to 10k and still make the system sleep with one eye open. I thought it best to start with the higher 10k value and work downward if necessary. For this reason I never tried less than 10k, because the initial run with 10k produced a rise toward 15 volts while still below 2200 alternator RPM. So I shut down and arbitrarily chose to increase the series value to 15k and the paralleling 1K to 3k, expecting this to probably be excessive and I could then fine tune with values in between. (SNIP)In this configuration, the voltage across the capacitor slowly rises to 0.6 volts within a 3 minute period after engine start while warming up at 1100 engine RPM (1430 alternator RPM). This is insufficient to bring the alternator on line if the Alternator switch is then turned on. (SNIP) | Hmmm . . . we would expect that. The target voltage would be much | higher and I would adjust the paralleling resistor upward from 1K | to adjust for desired value. Since my previous arrangement with the normally open push button switch activated the alternator at 1V (I didn't try it lower) why wouldn't it probably also respond at 1V in this current configuration, rather than needing 2-3V ? Just curious. (SNIP)However, as the engine RPM is advanced to the range of 1700-1800 for mag check, the alternator is now at 2210-2340 RPM with capacitor voltage slightly above 0.6 v and if the alternator switch is now turned on, the alternator comes alive to produce an unloaded buss voltage of slightly over 12 V. (SNIP) | Yeah, this would represent the minimum speed for regulation | (actually a tad low 'cause it's still not up to the regulator | setpoint) but insufficient rpm to deliver significant energy. The | fact that it 'came alive' is the significant point. Yes, I was initially concerned that the 0.6V meant I had badly over-corrected the resistors, but when the voltage rose rapidly as alternator speed rose beyond about 2200 RPM, I continued slowly to its maximum 3510 RPM without exceeding 14.42 V, still with the alternator off line. I then reduced RPM, waited for the capacitor voltage to stabilize around 0.6V and then increased speed slowly while periodically turning on the alternator switch, with no results until reaching close to 2100 alternator RPM, at which point the buss became alive with about 12V. Further speed increase raised the buss to a maximum of 14.42, which was the maximum all the way to 3510 limit RPM. I assumed the energy level at 0.6V was just too low to trigger the regulator but since it finally triggered at an RPM that is well below a reasonable in-flight value, maybe this is desirable and possibly avoids any tendency to exceed the upper 14V level while still providing the desired end result. (SNIP)This unloaded buss voltage continues to rise with RPM to a maximum of 14.42 V at engine rated 2700 RPM (alternator at 3510 RPM). As buss load is added, the regulator maintains 14.29 V until enough load is added to begin dropping the voltage in keeping with the alternator design current limits. With the Master switch still OFF, the buss voltage responds to the electrical load versus RPM in a predictable manner. Even if the RPM/load combination is carried to an extreme that produces buss voltage down to as little as 5 V, the alternator stays activated and comes back up in voltage to no higher than 14.42 if the load/RPM combination is re-adjusted. (SNIP) | Yup, as long as the output is kept above the wake-up voltage, | I would not expect it to go back to sleep. We're getting close | to a solution here. Find a value for the resistor in parallel | with the capacitor that gives us a wake-up voltage of 2-3 volts | at 2200 rpm. The voltage does rise rather rapidly as alternator RPM increases from the 1430 level toward the 2200 level where the alternator responded to being switched on. I didn't record the exact correlation and it might require a pretty slow engine power increase to allow for the larger-than-necessary capacitor to rise in voltage. I will attempt to get better data, but doing so in a ground run has some inherent operational hazards. The ideal method would be on a bench set-up. | The only time you would NEED the system to come up is in flight | and at 2200 rpm or higher. What we're looking for is the right | value for parallel R that gives us the 2-3 volts at 2200. I'm reasonably sure the voltage at 2200 RPM was several volts above 2-3. Is it desirable to not exceed 2-3 even though we're not now going above 14.42V maximum at 3510 RPM when off line? (SNIP)I suspect the system would respond differently with a smaller capacitor than the 56K mf unit that I adapted from my previous set-up, but I did not observe any undesirable features, and at this preliminary stage I believe the overall concept produces a fully automatic solution to eliminate the fear that a PM alternator could fail to come on line in the absence of a voltage source such as the ship's battery. (SNIP) | Yes. The fat electrolytic will take a few seconds to come up | to a static value but in this came, time is not critical. (SNIP)Please recognize that the above data during operation of the SD-8 just after engine start-up is not the condition of interest in normal operation. The engine (and alternator) would more likely be at higher RPM during cruise flight when the buss voltage might be lost while the SD-8 is not on line. In this situation,the alternator RPM and available voltage across the capacitor would already be high enough to immediately bring the alternator on line by simply turning the alternator switch on. I will soon verify this on an upcoming flight. (SNIP) | Okay. What you could do is bring a wire into the cockpit | off the filter capacitor. Put a fuse in series with it at | the capacitor end. You can fiddle with the load resistor | value and monitor voltage on the lead from the operator's | seat. The capacitor, paralleling resistor and quality digital test meter are all inside the cockpit, so this is not a problem. Do you recommend any change to the resistor between the diodes and ground from the 15k I now have in place? | I appreciate your time and interest in helping us craft | and conduct the experiment. Bob . . . I'm pleased to have your excellent guidance. Thanks for your time. Jim McCulley ________________________________ Message 9 _____________________________________ Time: 08:46:16 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Re: Charging system failure --> AeroElectric-List message posted by: Brian Lloyd On May 7, 2006, at 4:12 PM, DAVID REEL wrote: > > Is .02 ohms small enough for reasonable stability? How much > typically comes > from a circuit breaker? To be honest, I don't know. The answer is probably, "try it and see." The numbers you are now bandying about seem pretty reasonable to me. Remember, an alternator is NOT a precision bench supply with .001% regulation. I doubt a couple tenths of a volt will make a lot of difference. > At cruise rpm where field circuit amperage will presumably be less, > will > stability increase due to decreased voltage drop? I would expect it to. > Or will stability > decrease because the smaller current requires more precise > manipulation? No. > What happens to voltage in the millisecond range which I'd need an > oscilloscope to see? Will it be much less stable than what I'm > seeing on my > digital voltmeter? Well, I wasn't thinking of too much in the millisecond range but if you want to see how long it takes your alternator charging system to settle down after a big load change you aren't going to see it on a digital meter and an analog meter may be too slow also. That is where a cheap 'scope will help. You can set it to capture a single event at something like 100 ms per division and then see what happens. I think Bob has posted some of these traces but we are talking about YOUR system. > I should be able to fly again Tuesday & I guess, should I continue > to get OV > trips, I could always fly with nav lights on & see if that solved the > problem. Ugh! You just keep working at it, fixing one possibility after another until everything works right. If you don't mind hacking the guts of your regulator you might be able to pull the sense wire out separately. After all, this is EXPERIMENTAL aviation. Just a thought. Good luck! Brian Lloyd 361 Catterline Way brian-yak AT lloyd DOT com Folsom, CA 95630 +1.916.367.2131 (voice) +1.270.912.0788 (fax) I fly because it releases my mind from the tyranny of petty things . . . Antoine de Saint-Exupry