---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 06/21/12: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:02 AM - Re: Hall Effect rpm sensor (jhausch) 2. 06:29 AM - Tacho pulses (Eric M. Jones) 3. 03:39 PM - Re: Re: Viking Schematic (Robert L. Nuckolls, III) 4. 03:55 PM - Re: Re: RPM Sensor (Robert L. Nuckolls, III) 5. 04:00 PM - Re: Re: Hall Effect rpm sensor (Robert L. Nuckolls, III) 6. 04:54 PM - Re: Re: RPM Sensor (Michael Welch) 7. 05:02 PM - Re: Re: RPM Sensor (Michael Welch) 8. 06:28 PM - Re: Viking Schematic (user9253) ________________________________ Message 1 _____________________________________ Time: 05:02:33 AM PST US Subject: AeroElectric-List: Re: Hall Effect rpm sensor From: "jhausch" Bob, I have been receiving Mike's responses to my email. I only receive a daily digest from the list. I will leave it up to him to post the collection/recap of our conversation on the web. I was a bit surprised to see my work email signature pop up on the list, but I guess that's the nature of the internet. I've contacted encoder and prox vendors looking for 100' submersible solutions. I think that is the most challenging part of this application as viewed from my world. We have items rated for high pressure washdown, but 3 atm of constant pressure is likely another story.... You'd think a fully potted solid state solution would be fine, but my gut tells me the saltwater will creep in at the cable entry point and perhaps along the mating surfaces between the housing and potting material - searching for any void it can find to get at the electronics.... I agree with you that multiple PPR (pulses per rev) are needed to provide some accuracy/display stability. We'll see where this goes... certainly an interesting application. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376197#376197 ________________________________ Message 2 _____________________________________ Time: 06:29:14 AM PST US Subject: AeroElectric-List: Tacho pulses From: "Eric M. Jones" Based on recent discussions: Just a note to remind builders that I have a free tacho-pulse divide-by-two circuit if anyone wants one. I usually have PCBs too (cheap but not free) or can furnish the ExpressPCB design free. Contact me off list. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones(at)charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376201#376201 Attachments: http://forums.matronics.com//files/tacho_divider_133.jpg http://forums.matronics.com//files/tach_adapter_1_785.pdf ________________________________ Message 3 _____________________________________ Time: 03:39:42 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Viking Schematic At 12:22 PM 6/19/2012, you wrote: > >Bob, >My friend is building an RV-12 with an automotive engine, the >Viking, which is fuel injected and electrically dependent. The >power requirements for the ECU are not known but Viking uses 15 amp fuses. I've looked over the published instructions from Viking and the drawing you attached. The 'instructions' from Viking bear no demonstrable understanding of failure tolerant architecture for aircraft applications. There's a similar 'disconnect' from legacy and modern processes and techniques for aircraft wiring. If your friend is willing to bring his project to "The List" and submit performance numbers to mission goals, I (and probably others) would be willing to help him sort the bits and pieces to arrive at the elegant solution. But the drawing taken together with abysmal instructions do not describe a 'sandbox' in which I would want to play. I would further advise you to distance yourself from this project. I've been made aware of several problem projects wherein the builders conversed with me but for reasons of their own, chose to do other things . . . yet they claim to have consulted me in the crafting of their system. The engine is VERY experimental . . . which is not a singular cause for concern. But the entire electrical system is even more "experimental". Burt Rutan used to advise, "do your engine experiments on a TC aircraft and your airframe experiments with a TC engine." The overarching point is to drive risks to a minimum which must INCLUDE educating the owner/pilot on how the system works and what to do when things don't work. I suggest your worries over the bus isolation diode is but the tip of an iceberg in terms of having identified and crafted work-arounds for all perceived risks. Driving those risks up with decidedly untried or demonstrably unsuited techniques and materials. Bob . . . ________________________________ Message 4 _____________________________________ Time: 03:55:31 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: RPM Sensor At 12:43 PM 6/20/2012, you wrote: Jim, Bob, list members, Thank you for your responses. My initial request was brief, in an attempt to pay respect to the Matronics rules, since obviously my needs are not aviation related. They are, however, electronic in nature, and I, for one, always enjoy every electronic post, aviation or not, because I always enjoy learning from the best!! Since Bob suggests bringing the subject onto the this list, I hope those that read this topic are able to glean some electronic knowledge and, or share their skills. So, with an understanding this topic is not aero-electric, but yet it certainly is electronic, so it may help educate some of us electronic novices, here goes; Okay, 100' water pressure (50 PSI is no sweat). Digital display with say 1 RPM resolution and 0.5 RPM accuracy at 300 RPM maximum. Jim was asking about how the shaft speed to be measured was made available for electronic inspection . . . it could be as simple as counting passages of a woodruff key. In your case, the relatively slow speed combined with 1 part in 300 resolution probably precludes looking at one-count-per-rev signal sources . . . jitter in spacing of the counting edges can make an otherwise smoothly rotating shaft appear to be unstable. What length and diameter of the shaft is available to mount say a disk of magnets to be counted? Jim may have other ideas to offer but my first thought was based on a hall switch watching an array of 10 magnets. This could easily be made water proof to those pressures. Jim may be aware of an off the shelf, programmable instrument that would convert 300 counts per minute into a 300.0 RPM display. Such a device could be built too . . . the electronics is easy, PACKAGING is the hard part . . . especially for salt water service. Is this machine to be processor or computer guided? Would you want a tachometer to computer interface capability to know the current RPM? Except for the salt-water under pressure requirement and decidedly non-aircraft style motor shaft, this tachometer display task is not unlike that for aircraft applications. After selecting and interfacing a suitable sensor, one needs to know the 'scale factor' (pulses-per-revolution) from the sensor so that the readout can be appropriately configured. Bob . . . ________________________________ Message 5 _____________________________________ Time: 04:00:00 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Hall Effect rpm sensor At 06:59 AM 6/21/2012, you wrote: Bob, I have been receiving Mike's responses to my email. I only receive a daily digest from the list. I will leave it up to him to post the collection/recap of our conversation on the web. I was a bit surprised to see my work email signature pop up on the list, but I guess that's the nature of the internet. You were in a cc list and the reply-all response got you dumped into the List data flow but not in the bucket of List subscribed addresses. I've contacted encoder and prox vendors looking for 100' submersible solutions. I think that is the most challenging part of this application as viewed from my world. We have items rated for high pressure washdown, but 3 atm of constant pressure is likely another story.... You'd think a fully potted solid state solution would be fine, but my gut tells me the saltwater will creep in at the cable entry point and perhaps along the mating surfaces between the housing and potting material - searching for any void it can find to get at the electronics.... If you can find a square-wave (hall effect) driven instrument with the approrpiate features for scaling say 3000 ppm to a 300 rpm display, we can hammer a high pressure sensor together. I agree with you that multiple PPR (pulses per rev) are needed to provide some accuracy/display stability. We'll see where this goes... certainly an interesting application. Agreed. Let's see what kind of shaft is exposed to the inquisitive world of instrumentation. Bob . . . ________________________________ Message 6 _____________________________________ Time: 04:54:59 PM PST US Subject: Re: AeroElectric-List: Re: RPM Sensor From: Michael Welch Bob, See below for the answers to your questions. > > Okay, 100' water pressure (50 PSI is no sweat). Digital display with > say 1 RPM resolution and 0.5 RPM accuracy at 300 RPM maximum. Jim was > asking about how the shaft speed to be measured was made available for > electronic inspection . . . it could be as simple as counting passages > of a woodruff key. In your case, the relatively slow speed combined > with 1 part in 300 resolution probably precludes looking at one-count-per-rev > signal sources . . . jitter in spacing of the counting edges can > make an otherwise smoothly rotating shaft appear to be unstable. Regarding the pressure needed to work well, good (50 psi). The digital display with 1 rpm and .5rpm accuracy sounds perfect. I anticipate a splined shaft of approx. 1.75" diameter (for sprockets). If I need to add an extra couple of inches to allow for a rotating wheel, that would be no problem at all!! Are we talking about roughly 10 strong magnets, say...on a 6" diameter wheel? If so, that would be VERY easy to fabricate a fiberglass disc, encapsulating said magnets near the rim. > > What length and diameter of the shaft is available to mount say > a disk of magnets to be counted? Jim may have other ideas to offer > but my first thought was based on a hall switch watching an array > of 10 magnets. (Mine, too, and this would be an easy task to build) > This could easily be made water proof to those > pressures. Jim may be aware of an off the shelf, programmable > instrument that would convert 300 counts per minute into a 300.0 > RPM display. Such a device could be built too . . . the electronics > is easy, PACKAGING is the hard part . . . especially for salt > water service. Other than the sensor to read those rotating magnets, what else would need to be underwater? The sensor? That should be a sealed unit, no? Other than the 10-magnet disc and sensor, all other item are topside. The gauge/display unit would be in a water-tite console. > Is this machine to be processor or computer guided? Would you > want a tachometer to computer interface capability to know > the current RPM? > Except for the salt-water under pressure requirement and > decidedly non-aircraft style motor shaft, this tachometer > display task is not unlike that for aircraft applications. > After selecting and interfacing a suitable sensor, one needs > to know the 'scale factor' (pulses-per-revolution) from > the sensor so that the readout can be appropriately > configured. > No, not computer guided or driven. Hands on operation, but requiring only occasional adjustment, from information from the various rpm gauges. I think 10 pulses per rev is plenty good resolution. If we can read these magnets by way of a familiar sensor you have in mind, I'll make a parts order tomorrow, and get going making the disc. Bob, back a year ago when we were talking neodymium magnets & Hall Effect sensors for an airspeed indicator, I bought a handful of 1/8" x 1/8" x 1/2". They be small, but they be purdy strong! Will they work? Any ideas for the sensor? > > Bob . . . > > > ________________________________ Message 7 _____________________________________ Time: 05:02:47 PM PST US Subject: Re: AeroElectric-List: Re: RPM Sensor From: Michael Welch Bob, Is there any way we can make these display units work with our design? I REALLY like their products, I have two of them in my plane. One for turbo boost (from a MAP sensor), and one of their EGT gauges and senders. Nice stuff! http://www.auberins.com/index.php?main_page=product_info&cPath=16&prod ucts_id=212 The displays units are easy to mount, and are bright in sunlight. Mike Welch ________________________________ Message 8 _____________________________________ Time: 06:28:49 PM PST US Subject: AeroElectric-List: Re: Viking Schematic From: "user9253" Bob, Thanks for your words of wisdom so eloquently stated. I think that the Viking powered aircraft can be wired, for the most part, using one of your drawings. There is one item unique to the Viking that is not addressed: ECU SELECT. The Viking website recommends using one DPDT switch wired in parallel to act as a SPDT switch. This switch will select either a high or low voltage and send it to the dual ECUs to enable either ECU1 or ECU2. My concern is that if this switch fails, the pilot will not be able to switch to the backup ECU if needed. Or if the switch fails open, who knows which ECU will be enabled, if any. It is unknown what bad things might happen if both ECUs are enabled at the same time, even for a second. Is it safe to use one switch to choose between ECUs? If not, is there a better way than to use 2 mechanically interlocked switches? Perhaps a solid state circuit powered by the aircraft supply so that it would not load down the ECU. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=376273#376273 Attachments: http://forums.matronics.com//files/select_207.jpg ------------------------------------------------------------------------------------- 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.