AeroElectric-List Digest Archive

Thu 02/15/07


Total Messages Posted: 20



Today's Message Index:
----------------------
 
     1. 06:17 AM - Re: Radio audio troubles (Robert L. Nuckolls, III)
     2. 08:18 AM - Re: Electronics Intl MVP-50 Dsub 37's connectors (Robert L. Nuckolls, III)
     3. 09:37 AM - Re: Correct resistor for 12v LED (Peter Laurence)
     4. 09:41 AM - Re: Electronics Intl MVP-50 Dsub 37's connectors (Ernest Christley)
     5. 09:50 AM - Re: Correct resistor for 12v LED (Robert L. Nuckolls, III)
     6. 09:56 AM - Re: Electronics Intl MVP-50 Dsub 37's connectors (Dave N6030X)
     7. 12:07 PM - Re: Avionics-List: Re: Com audio issues ()
     8. 12:12 PM - Re: Radio audio troubles ()
     9. 12:14 PM - Re: Poor man's DAS (John and Kim Lumkes)
    10. 01:32 PM - Re: Correct resistor for 12v LED (6440 Auto Parts)
    11. 03:10 PM - Re: Hand soldering reliability (Dan Reeves)
    12. 03:49 PM - Re: Radio audio troubles ()
    13. 04:02 PM - Re: Com audio issues ()
    14. 04:08 PM - Re: Electronics Intl MVP-50 Dsub 37's connectors (Robert L. Nuckolls, III)
    15. 04:09 PM - Re: Speaker termination (Robert L. Nuckolls, III)
    16. 04:10 PM - Re: Hand soldering reliability (Robert L. Nuckolls, III)
    17. 04:18 PM - Re: Re: Com audio issues (Robert L. Nuckolls, III)
    18. 04:51 PM - Re: Poor man's DAS (Kevin Horton)
    19. 10:04 PM - Pulse width modulation on linear actuators (Tim Andres)
    20. 11:39 PM - Re: Pulse width modulation on linear actuators (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 06:17:46 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Radio audio troubles
    At 10:08 PM 2/14/2007 -0600, you wrote: > >Hi Gurus, > >It's been awhile, but I hope all is well with you all. > >I'm having audio issues with my new Becker 4201 #2 com and was wondering if >you could help. > >The issue is the output audio from the radio whenever there is another radio >switched into the same output. As soon as any other input is selected on >the audio panel at the same time, the com#2 volume goes very very low and is >overpowered. Sidetone during transmit seems un-affected as does the audio of >the other sources selected - only the Com2 audio drops down. By >itself...the radio sounds fine, and operates properly. > >The #1 com (iCom A200) works fine and is nice and loud with any number of >inputs selected on the audio panel (KA-134). Adding additional inputs has >little to no affect on com1 volume. It works great - as it should. > >According to the KA-134 schematics, the only thing it's doing with the phone >outputs from the radios is mechanically switching them (no electronics) >together to a single output line to the intercom. Because of this, I was >wondering if the impedance differences of the radios are a problem. >However, I have no real understanding of the magic involved here. > >They are as follows according to the respective docs: >Com1 iCom - 500 ohms >Com2 Becker - 600 ohms >Eng mon - 560 ohms >Nav KN-53 - 500 ohms >RST Marker Receiver - unknown Actually, those "output impedance" values are completely bogus. See: http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf The true output impedance of any of these devices is considerably lower than the values stated. What they really mean to say is, "This product will produce rated output performance when presented with xxx ohms of LOAD. If the mental image I have from reading your words is coincident with your own, then it appears that something may be amiss in the audio isolation amplifier. The whole idea of such a device is ISOLATION. This means that adding, deleting or suffering a failure in any of the audio sources should have no effect on performance of remaining sources. Try swapping affected radios to different inputs to the amplifier and see if the symptoms swap with the radios or stay common to the switches on the amplifier. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 2


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    Time: 08:18:42 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Electronics Intl MVP-50 Dsub 37's connectors
    At 09:08 PM 2/14/2007 -0500, you wrote: ><rtitsworth@mindspring.com> > > >Bob, etal > >I have an ElecIntl MVP-50 engine monitor. The various probes connect to >three Dsub 37 connectors on the box (via a user created harness). >To get the engine prob wires through the firewall I have a few options: > >1. Drill a hole, and use a flange and a piece of fire sleeve and a couple >wire ties (quick and cheep) >2. Get a few large Amp/mil-spec bayonet style multi-pin round plugs >(expensive and heavy) >3. Fabricate/find three Dsub 37 bulkhead connectors and use the provided >cable components and a standard Dsub 37-to-37 straight thru cable. Thus: >connect the probes to the provided Dsum37 connectors, connect those to the >dsub37 bulkhead connectors, connect the back side of those to the >dsub37-to-37 straight through cables, connect the other end of the cables to >the engine monitor box (dsub 37). i.e. Seems it would be "clean" to just >use the same style connectors throughout. > >Have you ever see a thing such as Dsub37 bulkhead socket? Not one that's fire-rated . . . >i.e. like a >normal one with bigger flanges. Have you ever seen one that had male pins >on one side and female plugs on the other (straight through)? Ideally it >would be > 1/2" depth in the center to get through the firewall. Or perhaps >a similar gender changer and then I'd find/make a mating cable? What's your design goal? If ease of installation an maintenance supercedes concerns for fire wall integrity, then panel mounted d-subs to take wires through the fire wall are a consideration. If it were my airplane, I'd take the bundle through fittings not unlike these . . http://aeroelectric.com/articles/Firewall_Penetration/firewall.html These are techniques used on some present production TC aircraft. There are no doubt equivalent and perhaps more attractive techniques. I've not had time to research them. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 3


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    Time: 09:37:35 AM PST US
    From: " Peter Laurence" <Dr.Laurence@mbdi.org>
    Subject: Re: Correct resistor for 12v LED
    Don, If I read this correctly, The max amps of the LED is 20MA. If this is being used in your airplane, then it's going to see approx. 13V. This would require a 13/.020 -- somewere around 650 ohm resistor. Peter > > I have several 12v, 12ma LED's from Radio Shack (part 276-272)in my panel. > According to the calculators (15V max Supply, 12V LED, 12ma), I need a > 27.0kohms, 1/8w resistor. Two questions: > > 1) led.linear1.org reports "The wizard thinks your forward voltage spec is > suspiciously high, but will proceed with the calculations.". The input > voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is > correct that it just does not recognize 12v LEDs? > > 2) Where do I find 1/8w resistors? > > Don Mack | don@dmack.net | dmack.net > > >


    Message 4


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    Time: 09:41:10 AM PST US
    From: Ernest Christley <echristley@nc.rr.com>
    Subject: Re: Electronics Intl MVP-50 Dsub 37's connectors
    Robert L. Nuckolls, III wrote: > > What's your design goal? If ease of installation an maintenance > supercedes concerns for fire wall integrity, then panel mounted > d-subs to take wires through the fire wall are a consideration. > I've either have, or have had, some D-subs that had a ceramic material in the center that held the pins. I have no technical data at all about what the filler material was, but it looked more robust than the typical plastic center sections. I don't know where I got the old connectors from, and a quick Google search didn't turn up anything useful. If I still have them in my toolbox, I'll post a picture before and after I put a torch to them. -- ,|"|"|, Ernest Christley | ----===<{{(oQo)}}>===---- Dyke Delta Builder | o| d |o http://ernest.isa-geek.org |


    Message 5


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    Time: 09:50:40 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Correct resistor for 12v LED
    Check this part out at: http://www.radioshack.com/product/index.jsp?productId 62570&cp It's not very explicit in the listing but examination of the photos shows a resistor already installed. Further, on one page, they call this a "12v" LED. This product can be hooked directly to your electrical system with NO external resistor needed. Bob . . . At 12:34 PM 2/15/2007 -0500, you wrote: ><Dr.Laurence@mbdi.org> > >Don, > >If I read this correctly, The max amps of the LED is 20MA. If this is >being used in your airplane, then it's going to see approx. 13V. This >would require a 13/.020 -- somewere around 650 ohm resistor. > >Peter > > >> >>I have several 12v, 12ma LED's from Radio Shack (part 276-272)in my panel. >>According to the calculators (15V max Supply, 12V LED, 12ma), I need a >>27.0kohms, 1/8w resistor. Two questions: >> >>1) led.linear1.org reports "The wizard thinks your forward voltage spec is >>suspiciously high, but will proceed with the calculations.". The input >>voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is >>correct that it just does not recognize 12v LEDs? >> >>2) Where do I find 1/8w resistors? >> >>Don Mack | don@dmack.net | dmack.net >> >> >> >> >> >> > > >-- >4:17 PM > > >-- incoming mail is certified Virus Free. >Checked by AVG. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 6


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    Time: 09:56:51 AM PST US
    From: Dave N6030X <N6030X@DaveMorris.com>
    Subject: Re: Electronics Intl MVP-50 Dsub 37's connectors
    Is there any problem with breaking a thermocouple wire at the firewall with a bulkhead connector? Dave Morris At 08:08 PM 2/14/2007, you wrote: ><rtitsworth@mindspring.com> > > >Bob, etal > >I have an ElecIntl MVP-50 engine monitor. The various probes connect to >three Dsub 37 connectors on the box (via a user created harness). >To get the engine prob wires through the firewall I have a few options: > >1. Drill a hole, and use a flange and a piece of fire sleeve and a couple >wire ties (quick and cheep) >2. Get a few large Amp/mil-spec bayonet style multi-pin round plugs >(expensive and heavy) >3. Fabricate/find three Dsub 37 bulkhead connectors and use the provided >cable components and a standard Dsub 37-to-37 straight thru cable. Thus: >connect the probes to the provided Dsum37 connectors, connect those to the >dsub37 bulkhead connectors, connect the back side of those to the >dsub37-to-37 straight through cables, connect the other end of the cables to >the engine monitor box (dsub 37). i.e. Seems it would be "clean" to just >use the same style connectors throughout. > >Have you ever see a thing such as Dsub37 bulkhead socket? i.e. like a >normal one with bigger flanges. Have you ever seen one that had male pins >on one side and female plugs on the other (straight through)? Ideally it >would be > 1/2" depth in the center to get through the firewall. Or perhaps >a similar gender changer and then I'd find/make a mating cable? > >Rick > >


    Message 7


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    Time: 12:07:56 PM PST US
    From: <berkut13@berkut13.com>
    Subject: Re: Avionics-List: Re: Com audio issues
    Yup...switches with "ganged" inputs. See below link for the schematic. (300K .jpg) http://www.berkut13.com/dloads/ka-134.jpg I'm glad you attached Dan's reply, I never received it. I guess I can perform surgery on the input lines and install a 220-ohm resistor on each. Yeah, it's a hunk of junk King! I wish I had never installed it...but it's far worse to try to extract it and start over now. Anyone know if the VAL (same size) has a isolation circuit built in? It might become a "throw money at it" solution if the resistors don't help. What I don't understand is why Com1 (iCom) can be "switched" in with all the other inputs with no adverse affects. But, the com2 (Becker) can't - ANY input source that's switches in takes the Becker to almost zero and, of course, when the volume is turned all the way up it's all distorted. Add all you want to the iCom and the blend in just fine. Is that what John is suggesting might be cause by the iCom possibly having a significantly lower impedance than the other radios? I can also tell you that the iCom's output is very robust compared to the other radios. It's quite loud, deep and clear with very little turn of the volume knob - very sensitive. Not sure that says anything other that it's got a good amp on it, but I'll put that out there too. Again, thanks for all the help! James ----- Original Message ----- From: "Jesse Kluijfhout, PE1RUI" <jessevli@zeelandnet.nl> Sent: Thursday, February 15, 2007 11:22 AM Subject: Avionics-List: Re: Com audio issues > --> Avionics-List message posted by: "Jesse Kluijfhout, PE1RUI" > <jessevli@zeelandnet.nl> > > Suspect the Icom for low impedance as Dan descriped. I did had the same > problem with a no audio panel (just switches) aircraft. When the Icom > audio output was turned on, the audio of the other radio would be very low > as well. The resistor as Dan descriped solved this issue. > > Best regards, > > Jesse >> It is rather poor practice to just mechanically parallel the outputs. >> Normally the audio panel would provide a simple op amp circuit which >> would >> enable the outputs to be combined without affecting each other at all. >> Are >> you sure it does just parallel them all up? If it does then I would >> expect >> any output to be attenuated noticeably when paralleling multiple others. >> John >> James, >> >> I agree with John. Actually the output impedance of each unit is >> probably >> not 500 or 600 ohms. It could be as small as 1 ohm or as large as 600 >> ohms, but >> >> designed to drive a 500 or 600 ohm load. If you put a resistor of about >> 200 >> ohms in series with each unit, then you give each one a chance to compete >> with >> >> the others. >> >> Dan Hopper >> RV-7A >> Retired EE


    Message 8


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    Time: 12:12:52 PM PST US
    From: <berkut13@berkut13.com>
    Subject: Re: Radio audio troubles
    > Actually, those "output impedance" values are completely > bogus. See: > > http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf > > The true output impedance of any of these devices > is considerably lower than the values stated. What > they really mean to say is, "This product will produce > rated output performance when presented with xxx ohms > of LOAD. I forwarded this to the office. It'll take a bit to read and absorb it. > If the mental image I have from reading your words is > coincident with your own, then it appears that something > may be amiss in the audio isolation amplifier. Amiss?...yup..there isn't one. So, that should be "amiss-ing" ;-) > Try swapping affected radios to different inputs to > the amplifier and see if the symptoms swap with the radios > or stay common to the switches on the amplifier. I sent an email with a link to the KA-134 schematic...it's just switches for these circuits to the "phones output". -James


    Message 9


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    Time: 12:14:47 PM PST US
    From: "John and Kim Lumkes" <lumkes@msoe.edu>
    Subject: Re: Poor man's DAS
    I can personally vouch for the Labjack series. I have purchased and installed approximately 25 units in a teaching laboratory; no matter how many mistakes the student made, only one unit ever failed and the factory replaced it at no charge. I now use them again at my "new" position, and have my own personal one at home. I have used it to record data around the house (temp's, flow, etc.) and plan on installing one in the airplane with a mini-ITX PC to have my own data logger / EIS. The interface can easily be done in Labview, and having the "carpc" will also allow me to run PocketFMS on a split screen. This is definitely "experimental" and so all required gauges will also be "steam wired". There so many ICs now like thermocouple amplifiers with built in cold junctions, small economical pressure transducers, etc., that adding features are easier now than ever before for amateur electrical system integrators (like myself). Long term plans: adding solid state gyros (IC chips now have this ability) for AHRS and wing leveling / GPS based auto-pilot. John


    Message 10


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    Time: 01:32:56 PM PST US
    From: "6440 Auto Parts" <sales@6440autoparts.com>
    Subject: Re: Correct resistor for 12v LED
    They look like they would make a very clean looking and easy install. Also looks like they have them in green and red. Randy ----- Original Message ----- From: "Robert L. Nuckolls, III" <nuckollsr@cox.net> Sent: Thursday, February 15, 2007 11:50 AM Subject: Re: AeroElectric-List: Correct resistor for 12v LED > <nuckollsr@cox.net> > > Check this part out at: > > http://www.radioshack.com/product/index.jsp?productId 62570&cp > > It's not very explicit in the listing but examination of the > photos shows a resistor already installed. Further, on one > page, they call this a "12v" LED. > > This product can be hooked directly to your electrical system with > NO external resistor needed. > > Bob . . . > > At 12:34 PM 2/15/2007 -0500, you wrote: > >><Dr.Laurence@mbdi.org> >> >>Don, >> >>If I read this correctly, The max amps of the LED is 20MA. If this is >>being used in your airplane, then it's going to see approx. 13V. This >>would require a 13/.020 -- somewere around 650 ohm resistor. >> >>Peter >> >> >> >> >>> >>>I have several 12v, 12ma LED's from Radio Shack (part 276-272)in my >>>panel. >>>According to the calculators (15V max Supply, 12V LED, 12ma), I need a >>>27.0kohms, 1/8w resistor. Two questions: >>> >>>1) led.linear1.org reports "The wizard thinks your forward voltage spec >>>is >>>suspiciously high, but will proceed with the calculations.". The input >>>voltage is listed as 12-16V, 12-20ma, so I ASSuME that the calculation is >>>correct that it just does not recognize 12v LEDs? >>> >>>2) Where do I find 1/8w resistors? >>> >>>Don Mack | don@dmack.net | dmack.net >>> >>> >>> >>> >>> >>> >> >> >> >> >> >> >> >>-- >>4:17 PM >> >> >> >> >> >>-- incoming mail is certified Virus Free. >>Checked by AVG. > > > Bob . . . > > ---------------------------------------- > ( IF one aspires to be "world class", ) > ( what ever you do must be exercised ) > ( EVERY day . . . ) > ( R. L. Nuckolls III ) > ---------------------------------------- > > >


    Message 11


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    Time: 03:10:44 PM PST US
    From: Dan Reeves <n516dr@yahoo.com>
    Subject: Re: Hand soldering reliability
    Exactly! Nothing against great doco and processes but, in my opinion, the real goal of ISO, CMM, etc is to make people Plug and Play. After all, who needs a highly skilled Robert L. Nuckoll's for example when you can Unplug him and Play someone else who has their handy-dandy, repeatable, ISO, CMM, certified, process in hand? (Rhetorical question,,,,I do!!!) Creativity? ISO, CMM, etc are the kiss of death in this regard. A process is like a road map with one road on it. Hit a roadblock and good luck getting anyone to realize there are a million other roads that will take you to the same place. Tools? I hear there are great tools out there like laser scapal's,,,doesn't make me want let someone who is unskilled anywhere near me even though they have a great tool. Managers seem to confuse the concept that great tools make the highly skilled more productive,,,,they don't make the unskilled skilled. "Robert L. Nuckolls, III" <nuckollsr@cox.net> wrote: At 02:02 PM 2/14/2007 -0800, you wrote: > >You don't have it wrong but that's because ISO9000 says nothing about the >quality of the end product. All being ISO9000 certified means is you've >documented the processes you use and you perform periodic reviews (I'm WAY >oversimplifying and paraphrasing here but that's basically it). > >The idea is that you document the key processes so that results are >repeatable. They can be repeatably bad or repeatably good. Think of it >as the commercial version of "mil-spec". Things can be spec'd to turn out >like junk but you know that every one is junky in exactly the same way :) Yup. You got it. The fly in the soup is that one presumes that: (1) the process is golden. (2) the folks who describe the process used language that paints the same image in the reader's mind as the writer had when the words were written. (3) the reader can read and understand what is read. (4) if product doesn't come out as depicted in the process, it's presumed to be a problem with folks not following the rules. The whole idea was that proper documentation for any process could replace mentoring, apprenticeship, and replace dependency on continuous refinement of skills through experience. When I know that the ISO audit folks are going to be in the area, I'm careful to be out of the area. I'd hate to embarrass my boss. Bottom line is that documents crafted to satisfy the ISO9000 model are seldom very useful to craftsmen who strive to understand the processes they're using. Bob . . . --------------------------------- We won't tell. Get more on shows you hate to love (and love to hate): Yahoo! TV's Guilty Pleasures list.


    Message 12


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    Time: 03:49:59 PM PST US
    From: <berkut13@berkut13.com>
    Subject: Re: Radio audio troubles
    Yup...switches with "ganged" inputs. See below link for the schematic. (300K .jpg) http://www.berkut13.com/dloads/ka-134.jpg I'm glad you attached Dan's reply, I never received it. I guess I can perform surgery on the input lines and install a 220-ohm resistor on each. Yeah, it's a hunk of junk King! I wish I had never installed it...but it's far worse to try to extract it and start over now. Anyone know if the VAL (same size) AP-100 has a isolation circuit built in? It might become a "throw money at it" solution if the resistors don't help. What I don't understand is why Com1 (iCom) can be "switched" in with all the other inputs with no adverse affects. But, the com2 (Becker) can't - ANY input source that's switches in takes the Becker to almost zero and, of course, when the volume is turned all the way up it's all distorted. Add all you want to the iCom and the blend in just fine. Is that what John is suggesting might be cause by the iCom possibly having a significantly lower impedance than the other radios? I can also tell you that the iCom's output is very robust compared to the other radios. It's quite loud, deep and clear with very little turn of the volume knob - very sensitive. Not sure that says anything other that it's got a good amp on it, but I'll put that out there too. Again, thanks for all the help! James ----- Original Message ----- From: "Jesse Kluijfhout, PE1RUI" <jessevli@zeelandnet.nl> Sent: Thursday, February 15, 2007 11:22 AM Subject: Avionics-List: Re: Com audio issues > --> Avionics-List message posted by: "Jesse Kluijfhout, PE1RUI" > <jessevli@zeelandnet.nl> > > Suspect the Icom for low impedance as Dan descriped. I did had the same > problem with a no audio panel (just switches) aircraft. When the Icom > audio output was turned on, the audio of the other radio would be very low > as well. The resistor as Dan descriped solved this issue. > > Best regards, > > Jesse >> It is rather poor practice to just mechanically parallel the outputs. >> Normally the audio panel would provide a simple op amp circuit which >> would >> enable the outputs to be combined without affecting each other at all. >> Are >> you sure it does just parallel them all up? If it does then I would >> expect >> any output to be attenuated noticeably when paralleling multiple others. >> John >> James, >> >> I agree with John. Actually the output impedance of each unit is >> probably >> not 500 or 600 ohms. It could be as small as 1 ohm or as large as 600 >> ohms, but >> >> designed to drive a 500 or 600 ohm load. If you put a resistor of about >> 200 >> ohms in series with each unit, then you give each one a chance to compete >> with >> >> the others. >> >> Dan Hopper >> RV-7A >> Retired EE


    Message 13


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    Time: 04:02:03 PM PST US
    From: <berkut13@berkut13.com>
    Subject: Re: Com audio issues
    Referring to the schematic for the KA-134 in previous email: >>Are you sure that the switches connect the output of your problem >>audio source directly to another output? Maybe I have missed something. > I see what I was missing! I didn't see the "headphone out" at the top > right. Yeah...and the bloody thing is marketed as having an isolation amp built in. That's true...but what they don't tell you is that it's for the cabin speaker and ramp hail ONLY! Grrrrr!!


    Message 14


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    Time: 04:08:39 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Electronics Intl MVP-50 Dsub 37's connectors
    At 11:55 AM 2/15/2007 -0600, you wrote: > >Is there any problem with breaking a thermocouple wire at the firewall >with a bulkhead connector? Not at all . . . with reservations. As you pass from thermocouple wire to (stuff) to thermocouple wire, you need to be sure that you do exactly the same thing to the other paired thermocouple conductor. I've used a LOT of d-sub connectors to make handy breaks in bundles containing thermocouple wires. Use the machined pins to get a really good grip on the thermocouple wire and it will be fine. Yes, you're introducing "foreign" alloys into the system however, the "new" thermocouples are always in pairs and co-located so that their effects are equal-opposite and cancel out. Bob . . .


    Message 15


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    Time: 04:09:59 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Speaker termination
    At 09:07 AM 2/15/2007 -0500, you wrote: >Hi Bob, > I'm about to close up the front of my "9" and there is a pair of >wires coming from the Icom A200 for an external speaker. Should I >terminate them with a resistor or just leave them open. I do not intend >to utilize a speaker in the cockpit. Good for you. Refer to the instruction manual. If they don't call out a dummy load, you can just leave it open. Actually, the few radios I've see that called for a dummy load on unused outputs would probably have been quit stable without it. The only think I can think of that would prompt a designer to require loading an unused input is to accommodate an output stage instability under light loads. Modern audio amplifier ships don't have this problem. Bob . . .


    Message 16


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    Time: 04:10:24 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Hand soldering reliability
    At 10:31 PM 2/14/2007 -0600, you wrote: > > The bottom line is that 95% plus of these documents is > > either ignored or forgotten in the practice of processes > > described therein. Of course, when some quality issue > > pops up that can be attributed to "failure to observe > > the ISO9000 approved processes", then some poor sap > > can be tagged with fault and summarily dealt with. > >Quality circles, TQM, 6-Sigma, and all the rest now in the dust >bin....the ISO business seems to have more legs than most of >the others, tho. After awhile you'll spend most of your time >tracking performance instead of performing. I guess humans are >just hell-bent to quantify everything. Not all humans, just those tasked with 'managing' processes they do not understand. The Policy and Procedure meme is a "Virus of the Mind". See . . . http://www.cscs.umich.edu/~crshalizi/Dawkins/viruses-of-the-mind.html Some such virii have run their course in the adventures of human kind, others are still growing and there are certainly new ones yet to germinate, gestate and run their courses. I'm working a noise issue on a motor right now that is plagued with a variety of memes . . . all of which push us away from the best-we-know-how-to-do, add weight to the airplane, generate cert programs that will run months, and produce far too many customers who will remember unhappy experiences with out product. The science for the solution is stone simple, light, and an excellent example of how two gray-haired ol' farts sat down and pooled their collective understanding and experience. Of course, this runs against the ISO9000 and FAR memes. I have suggested on occasion that our official ISO9000 documentation package could be reduced to one page that states, "Hire smart folks, give them authority and then run out ahead of your troops removing impediments to progress." Instead, all of the folks I work with are suffering various forms of paralysis that arise from their own intellectual virii. My task is made several times more difficult because I have to take on the role of physician specializing in maladies that have nothing to do with engineering. Its a dirty job but somebody's got to do it. Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 17


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    Time: 04:18:58 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Com audio issues
    At 05:56 PM 2/15/2007 -0600, you wrote: > >Referring to the schematic for the KA-134 in previous email: > >>>Are you sure that the switches connect the output of your problem >>>audio source directly to another output? Maybe I have missed something. > >>I see what I was missing! I didn't see the "headphone out" at the top right. > > >Yeah...and the bloody thing is marketed as having an isolation amp built >in. That's true...but what they don't tell you is that it's for the cabin >speaker and ramp hail ONLY! Grrrrr!! Hmmmm . . . well . . . there's always plan-b: http://www.aeroelectric.com/DIY/Audio_Isolation_Amplifier.pdf Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------


    Message 18


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    Time: 04:51:19 PM PST US
    From: Kevin Horton <khorton01@rogers.com>
    Subject: Re: Poor man's DAS
    On 15 Feb 2007, at 15:11, John and Kim Lumkes wrote: > I can personally vouch for the Labjack series. I have purchased and > installed approximately 25 units in a teaching laboratory; no > matter how many mistakes the student made, only one unit ever > failed and the factory replaced it at no charge. I now use them > again at my "new" position, and have my own personal one at home. I > have used it to record data around the house (temp's, flow, etc.) > and plan on installing one in the airplane with a mini-ITX PC to > have my own data logger / EIS. The interface can easily be done in > Labview, and having the "carpc" will also allow me to run PocketFMS > on a split screen. This is definitely "experimental" and so all > required gauges will also be "steam wired". There so many ICs now > like thermocouple amplifiers with built in cold junctions, small > economical pressure transducers, etc., that adding features are > easier now than ever before for amateur electrical system > integrators (like myself). Bob and John, Thank you very much for the recommendation for the Labjack. This unit should allow me to add some missing items to my flight test data. John - where do you purchase suitable, affordable, robust transducers? I'm looking to measure some temperatures, and flight control positions. Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://www.kilohotel.com/rv8 do not archive


    Message 19


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    Time: 10:04:17 PM PST US
    From: "Tim Andres" <tim2542@sbcglobal.net>
    Subject: Pulse width modulation on linear actuators
    Can any one tell if the duty cycle on a PWM will equate at least roughly with motor speed? ie will a 20% duty cycle slow the motor down to approximately %20 or does it not work that way? I have a linear actuator for pitch trim that that travels 2"/sec, I need about .5"/sec. Thanks, Tim Andres --


    Message 20


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    Time: 11:39:55 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Pulse width modulation on linear actuators
    At 09:55 PM 2/15/2007 -0800, you wrote: > >Can any one tell if the duty cycle on a PWM will equate at least roughly >with motor speed? ie will a 20% duty cycle slow the motor down to >approximately %20 or does it not work that way? I have a linear actuator for >pitch trim that that travels 2"/sec, I need about .5"/sec. Probably. PM motors have field fields which makes RPM proportional to applied voltage. The RMS (power) available from any source is also proportional to duty cycle for a non-continuous flow. In any case, I presume you're going to make the duty cycle adjustable so whether it takes 25% duty cycle or 27% duty cycle to achieve exactly the speed you want is irrelevant. You can also use linear techniques. An adjustable but regulated voltage source not unlike the dimmers described in . . . http://www.aeroelectric.com/articles//DimmerFabrication.pdf . . . may be considered also. How much current does your motor draw at full speed? Bob . . . ---------------------------------------- ( IF one aspires to be "world class", ) ( what ever you do must be exercised ) ( EVERY day . . . ) ( R. L. Nuckolls III ) ----------------------------------------




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