---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 05/06/06: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:42 AM - Re: SAE documentation question (Eric M. Jones) 2. 06:50 PM - wiring diagram-sperry (Christopher Stone) 3. 08:59 PM - Re: SD-8 PM Alternator (J. Mcculley) 4. 09:23 PM - Re: SD-8 PM Alternator (Ron Shannon) ________________________________ Message 1 _____________________________________ Time: 06:42:40 AM PST US Subject: AeroElectric-List: Re: SAE documentation question From: "Eric M. Jones" --> AeroElectric-List message posted by: "Eric M. Jones" Usually your local librarian can get SAE docs and DO-160 docs and all sort of amazing stuff (the'll even do business by email. Your tax dollars at work. Your local copy shop will be happy to make a copy for you. Don't forget to point out to them that this is a copyright violation. Ahem... -------- 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=33123#33123 ________________________________ Message 2 _____________________________________ Time: 06:50:27 PM PST US From: Christopher Stone Subject: AeroElectric-List: wiring diagram-sperry --> AeroElectric-List message posted by: Christopher Stone Hello all... I am hoping that someone might have or know where I might find a pinout diagram for a Sperry IN-381A converter indicator head (GS/LOC/VOR). I have struckout with the major avioncs sellers. Thanks, Chris Stone Newberg, OR ________________________________ Message 3 _____________________________________ Time: 08:59:15 PM PST US From: "J. Mcculley" Subject: Re: AeroElectric-List: SD-8 PM Alternator --> 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: (SNIP)Your experiments have shown that the regulator will come alive > with a very low voltage available at the 'b-lead'. A study > of the schematic for the Kubota regulator leads one to > conclude that once you have just enough voltage to forward > bias some junctions (The b-e junction of Q3 through R3 > and D6) there is a potential for triggering the SCRs and > having the system wake up. I suspect the B&C regulator > is similar. > I thought of another approach to suggest. Since you're set up for and have the mind-set to conduct the necessary experiments,please consider . . . > > http://www.aeroelectric.com/Pictures/Schematics/PM_Regulator/Self_Excitation_Experiment.jpg > > What we'd like to do is not let the b-lead voltage out > of the regulator be 100% dependent upon triggered SCRs in > the regulator. Suppose you added a couple of diodes > from the alternator winding along with a resistor to > ground to build a very inefficient keep-alive rectifier. > The two diodes parallel the SCRs but with a conduction > impedance too high for the system to deliver significant > power. We then need some small, fixed 'load' across the > output filter capacitor to prevent the unloaded alternator > voltage (as high as 40v) from charging the capacitor > to a level dangerous to the cap and system equipment > in case the alternator control relay is closed while the > capacitor is charged up. > > I've shown a pair of 1K resistors. Use mechanically > hefty resistors . . . the 2W isn't need for electrical > reasons, just mechanical. Adjust the size of the series > resistor at the diodes to achieve a couple of volts or > more (but not greater than 14) across the capacitor > at max engine rpm with the alternator system OFF. > I suspect this resistor might be as high as 3 to 10K > and still make the system sleep with one eye open. > Here, we have an opportunity to go a step further > and modify the regulator's performance such that > it never quite goes to sleep and eliminate the > need for pilot intervention to kick-start the > system. If you can assist in conduction of this > experiment, we can prove/disprove my hypothesis > and perhaps generate an article that will help > others slay this dragon too. > Bob . . . (SNIP) 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. 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. 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. 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. 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. 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. Jim McCulley ------------------------------------------------------------------------- ________________________________ Message 4 _____________________________________ Time: 09:23:00 PM PST US From: Ron Shannon Subject: Re: AeroElectric-List: SD-8 PM Alternator --> AeroElectric-List message posted by: Ron Shannon Jim, Thanks for the report on your excellent work! Am looking forward to further chapters in this story, as your time permits. Ron