AeroElectric-List Digest Archive

Fri 07/16/10


Total Messages Posted: 8



Today's Message Index:
----------------------
 
     1. 08:32 AM - Ducati regulator question (user9253)
     2. 09:42 AM - Vertex VXA700 information needed (rparigoris)
     3. 09:54 AM - Re: Panel Accessible breaker for Mission Critical Item (Dennis Johnson)
     4. 11:38 AM - Re: Ducati regulator question (John Loram)
     5. 11:58 AM - Re: Facet Boost Pump Fuses (messydeer)
     6. 05:56 PM - Re: Ducati regulator question (Robert L. Nuckolls, III)
     7. 06:05 PM - Re: Facet Boost Pump Fuses (Robert L. Nuckolls, III)
     8. 09:21 PM - Electrical Noise Prevention (messydeer)
 
 
 


Message 1


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    Time: 08:32:17 AM PST US
    Subject: Ducati regulator question
    From: "user9253" <fran4sew@banyanol.com>
    I am building an RV-12. Because I am registering as E-LSA, I must build it EXACTLY according to plans using the pre-assembled wiring harness and control board, essentially a plug and play system. The schematic may be viewed here: http://www.vansaircraft.com/pdf/revisions/RV-12/User_Manuals/MM-R1.pdf on page 173 of the 185 page of the Adobe document. My question concerns the 22awg wire that connects the main bus to the "C" terminal of the Ducati voltage regulator. First of all, there is no fuse protection for this 3-foot wire that passes through the firewall. One half of the master switch is in series with this wire. I thought the "C" terminal was for voltage sensing. It seems that it is being used as an ON-OFF control for the regulator on the RV-12. If terminal "C" really is a voltage-sense input, then it would seem that if the master switch were shut off while the engine was running, that the regulator would see a low input (0 volts) and put out a higher voltage, resulting in an over-voltage situation. Another concern is the 22,000f 25vdc capacitor on the control board which is on the cabin side of the firewall. If the regulator fails and can not be shut off, an over-voltage situation could smoke the capacitor with no way to shut the power off to it. So here are my questions: Does terminal "C" of the Ducati regulator act as an ON-OFF control? If the regulator fails and allows over-voltage, will opening input to terminal "C" shut off the regulator output? Thanks, Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305065#305065


    Message 2


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    Time: 09:42:09 AM PST US
    Subject: Vertex VXA700 information needed
    From: "rparigoris" <rparigor@suffolk.lib.ny.us>
    I am trying to hook up a Vertex VXA700 handheld as a second Com to my PS Engineering PSA4000 audio panel. Here is link to owners manual (1.01MB): http://www.vertexstandard.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID 4&encProdID=CDA841ED5B9711A5833A60A9115F5EDE&DivisionID=2&isArchived=1 As per manual on page 65 I have a CT-96 headset cable. The problem is I want the audio panel to allow the Pilot and Co-Pilot PTT to transmit on Com 2 (Vertex) when I select Com 2. Does anyone have a schematic how to wire the CT-96 headset cable to accomplish this task? I do have as shown on page 65 the external PTT switch. This is not a simple device that goes in series with the mic jack and pulls PTT wire to ground. It has two switches that I believe could be replicated with a relay that has the coil powered and could look for ground through the PTT pin of Com 2 on the PMA 4000. I think when the external PTT switch/es are pushed, it disables the handhelds internal mic while connecting to the mic on headset. Vertex was not of much assistance. They sent over a Service manual and a diagram of CT-96, which have errors. When I asked another question that would have solved my issue, Vertex said they don't make the external PTT and couldn't help me any further. Thx. Ron Parigoris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305075#305075


    Message 3


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    Time: 09:54:33 AM PST US
    From: "Dennis Johnson" <pinetownd@volcano.net>
    Subject: RE: Panel Accessible breaker for Mission Critical Item
    I've been flying my Lancair Legacy for over three years and 350 hours. I do not agree with your characterization of a no flap landing in a Legacy. I wouldn't fly it if I thought it was unsafe to land without flaps. You're right that you need a higher landing speed and a longer runway, but at least where I fly, there are a dozen suitable runways within my normal fuel reserve. The last time I did a no flap landing, for practice, was on a 6,000' runway at sea level and I don't think I used more than half the runway. But it is something that needs to be practiced because you're right that it's much easier with flaps than without. There are plenty of single points of failure in the flap system and the fuse or circuit breaker is only one of them. I'd recommend a comfortable Plan B if any of them caused a flap system failure. By the way, I have a 7 amp ATO/ATC fuse protecting my wing flap circuit. During construction, I installed a 5 amp fuse based on measurements of the flap motor's current draw. However, once I started flying, I found that I could sometimes blow the fuse if I instantly reversed the flap direction. For example, let's say I'm on the ground running the before takeoff checklist and lowering the flaps to 10 degrees. I overshoot a little and immediately move the flap lever to the up position to get back to 10 degrees. That immediate reversal of flap movement sometimes blew the 5 amp fuse. I replaced it with a 7 amp fuse and have not had a problem since; about three years and over 300 hours. Another poster expressed concern about circuit protection for the landing gear. That's near the bottom of my worries, because the backup gear extension system relies on gravity and proper installation and lubrication of the landing gear system. I practice the alternate landing gear extension from time to time and perhaps that's why I'm so comfortable with it. My hydraulic pump is protected by a 40 amp ANL current limiter, which I don't believe the pump could possibly blow, absent some failure that would disable the system anyway. Dennis


    Message 4


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    Time: 11:38:41 AM PST US
    From: "John Loram" <johnl@loram.org>
    Subject: Ducati regulator question
    begin SPECULATION While it may have a "sense" function, it is probably the power source for the internal electronics. Without the source, the internal electronics won't startup, and the regulator will remain dormant. end SPECULATION This configuration, with a motorcycle regulator, was used on the early Jabiru engines and in that application powering the regulator without having the engine running would burn out the regulator and the alternator. -john- > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On > Behalf Of user9253 > Sent: Friday, July 16, 2010 8:31 AM > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Ducati regulator question > > --> <fran4sew@banyanol.com> > > I am building an RV-12. Because I am registering as E-LSA, I > must build it EXACTLY according to plans using the > pre-assembled wiring harness and control board, essentially a > plug and play system. The schematic may be viewed here: > http://www.vansaircraft.com/pdf/revisions/RV-12/User_Manuals/M > M-R1.pdf on page 173 of the 185 page of the Adobe document. > My question concerns the 22awg wire that connects the main > bus to the "C" terminal of the Ducati voltage regulator. > First of all, there is no fuse protection for this 3-foot > wire that passes through the firewall. One half of the > master switch is in series with this wire. I thought the "C" > terminal was for voltage sensing. It seems that it is being > used as an ON-OFF control for the regulator on the RV-12. If > terminal "C" really is a voltage-sense input, then it would > seem that if the master switch were shut off while the engine > was running, that the regulator would see a low input (0 > volts) and put out a higher voltage, resulting in an > over-voltage situation. Another concern is the 22,000f > 25vdc capacitor on the control board which is on the cabin > side of the firewall. If the regulator fails and can not be > shut off, an over-voltage situation could smoke the capacitor > with no way to shut the power off to it. So here are my questions: > Does terminal "C" of the Ducati regulator act as an ON-OFF control? > If the regulator fails and allows over-voltage, will opening > input to terminal "C" shut off the regulator output? > Thanks, > Joe > > -------- > Joe Gores > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=305065#305065 > > > > > > > > Photoshare, and much much more: > > > >


    Message 5


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    Time: 11:58:18 AM PST US
    Subject: Re: Facet Boost Pump Fuses
    From: "messydeer" <messydeer@yahoo.com>
    Thanks, Bob :-) Nice to get some background on how the pump works. Facet told me in an email 5A would be fine, I see from Table 11-3 of AC43.13-1B a 5A fuse would work, and you say 7A is peachy. So I'm happy and will think no more about this issue. -------- Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305105#305105 Attachments: http://forums.matronics.com//files/dc_wire_and_circuit_protector_chart_784.jpg


    Message 6


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    Time: 05:56:57 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Ducati regulator question
    At 01:35 PM 7/16/2010, you wrote: > >begin SPECULATION >While it may have a "sense" function, it is probably the power source for >the internal electronics. >Without the source, the internal electronics won't startup, and the >regulator will remain dormant. >end SPECULATION Seems reasonable. Here's a schematic someone sent me of what was believed to be at least one version of a Ducati PM alternator rectifier/regulators. It's typical of many other diagrams I've seen: http://aeroelectric.com/Pictures/Regulators/regul_912.jpg The "C" lead is indeed a voltage sense lead. Further, it powers the regulation + SCR control circuits. >This configuration, with a motorcycle regulator, was used on the early >Jabiru engines and in that application powering the regulator without having >the engine running would burn out the regulator and the alternator. > While this lead exercises ON/OFF control of the R/R, it's not in a position to do serious harm if left powered while the engine is not running. It's worst risk is that over a long period of time, it might run a battery down with what amounts to perhaps tens of milliamps of steady current draw. > > I am building an RV-12. Because I am registering as E-LSA, I > > must build it EXACTLY according to plans using the > > pre-assembled wiring harness and control board, essentially a > > plug and play system. The schematic may be viewed here: > >http://tinyurl.com/2d4b9j8 > > on page 173 of the 185 page of the Adobe document. > > My question concerns the 22awg wire that connects the main > > bus to the "C" terminal of the Ducati voltage regulator. > > First of all, there is no fuse protection for this 3-foot > > wire that passes through the firewall. Yes . . . this is not in agreement with legacy esign goals for aircraft . . . > > One half of the > > master switch is in series with this wire. I thought the "C" > > terminal was for voltage sensing. It seems that it is being > > used as an ON-OFF control for the regulator on the RV-12. If > > terminal "C" really is a voltage-sense input, then it would > > seem that if the master switch were shut off while the engine > > was running, that the regulator would see a low input (0 > > volts) and put out a higher voltage, resulting in an > > over-voltage situation. You'd be correct if this were not ALSO a power supply wire for the R/R . . . > Another concern is the 22,000=C2=B5f > > 25vdc capacitor on the control board which is on the cabin > > side of the firewall. If the regulator fails and can not be > > shut off, an over-voltage situation could smoke the capacitor > > with no way to shut the power off to it. Also correct . . . > > here are my questions: > > Does terminal "C" of the Ducati regulator act as an ON-OFF control? Yes > > If the regulator fails and allows over-voltage, will opening > > input to terminal "C" shut off the regulator output? Very probably. Further, given that the output capability for the Rotax (and all PM) alternator is relatively low, the voltage is not going to climb precipitously . . . If you had an ACTIVE NOTIFICATION of high voltage, this would probably suffice to offer timely crew notification. Alternatively, you could add active OV protection like that illustrated in http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z16M.pdf I would further suggest, active notification of low voltage is a good thing too. Finally, a 3A fuse in series with the "C" lead would be in conformity with legacy design goals. Bob . . .


    Message 7


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    Time: 06:05:23 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Facet Boost Pump Fuses
    > If it's 20AWG, put a 7A fuse in an don't loose > any sleep over it. Having too robust a feeder > protection cannot put anything inside the pump > at risk. > Would this reasoning not lead to running "really" robust feeders/fuses, and then a fuel pump (or other device) with and internal problem that is generating a lot of heat (fire/smoke)? I agree that we're not trying to 'save/protect' the pump, rather trying to prevent smoking wires, but a smoking load can be a big problem, too. Most devices we use in our airplanes are considered not flight worthy if they exhibit any failure mode that becomes a hazard source for combustion . . . emitting smoke is frowned upon too. The "really robust" feeders was more rhetorical than anything else . . . after all, with a fuse block, one has the option of selecting the optimal fuse for each application . . . and easily changing it if later circumstances suggest it's a good idea. Specifically, with the FACET being a low energy device totally enclosed in a metal box. The risks are nil . . . Emacs! Although I seem to recall that G. Richter suggested that the entire airplane could be configured with an array of one-size-fits-all, self-resetting PTC polyswitches soldered to a nifty etched circuit board product he offered. But when it's so easy to achieve the elegant solution, why not do it? Bob . . .


    Message 8


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    Time: 09:21:55 PM PST US
    Subject: Electrical Noise Prevention
    From: "messydeer" <messydeer@yahoo.com>
    Hi! I'm finishing up my electrical wiring and am wondering about noise. I'm not sure what types there are, nor do I know all the sources. I have heard the alternator and the transmitting radio can cause problems. Also heard that anything with a pulsing signal could also be a source. I have a 3 or 4 100-150 Mhz ferrite RF suppressors from MGL http://www.mglavionics.com/EMI_suppressor_for_VHF_frequencies.pdf. It sounds like MGL recommends putting them on any output from the radio, but not the antenna. I've heard that twisting the feeder line to the noise maker with it's ground coming back from the device (or having the wires next to each other) will help cancel out EMF generated noise. My schematic is posted in another thread: http://www.matronics.com/forums/viewtopic.php?t=72713. The two alternator leads are about 1' long and are wrapped together until one separates to go to the regulator and the other to the alt disconnect relay, which is right next to the regulator. The regulator output wire goes ~6" to a 10k micro (10 mili?) F 50V filter capacitor. I forgot to label the left and right mag wires, which are dangling out the bottom center of the pic. The engine instruments will be 6 cht's, 6 egt's, fuel pressure sender, fuel flow sensor, OT, OP, carb temp, and tach. All these will plug into the RDAC above the battery. A shielded data cable goes from there back to the EFIS. All the wires go through the firewall in either of two firewall penetations, then join together going to the right side, then back to the instrument panel and into a wire wrap along a light channel 'tray' along the bottom of the instrument panel. The pic shows the panel rotated 90 degrees in the open position. Most of the wires hanging loose are grounds. They'll be bundled together in the final installation, and if needed, close to the panel feed wires already wrapped. Besides the mag wires (which are shielded), the only wire with pusling would be the boost pump. The radio (which may be a handheld) and strobe/nav/pos lights are not in. I know strobes are notorious noise makers. I have the shielded cable installed already in the wings. How does this look to you? Thanks again for taking your time helping me :-) -------- Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305153#305153 Attachments: http://forums.matronics.com//files/cabin_wiring_labeled_836.jpg http://forums.matronics.com//files/firewall_electrical_components_labeled_828.jpg




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