AeroElectric-List Digest Archive

Tue 12/13/16


Total Messages Posted: 8



Today's Message Index:
----------------------
 
     1. 11:59 AM - Re: led trim display (spcialeffects)
     2. 03:49 PM - Trim position indicator (donjohnston)
     3. 04:32 PM - Re: Trim position indicator (Matt Dralle)
     4. 04:52 PM - Re: Trim position indicator (Alec Myers)
     5. 05:43 PM - Re: Trim position indicator (donjohnston)
     6. 06:34 PM - Re: Trim position indicator (Robert L. Nuckolls, III)
     7. 06:52 PM - Re: Trim position indicator (ashleysc@broadstripe.net)
     8. 07:20 PM - Re: Trim position sensor (user9253)
 
 
 


Message 1


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    Time: 11:59:08 AM PST US
    Subject: Re: led trim display
    From: "spcialeffects" <spcialeffects@aol.com>
    nuckolls.bob(at)aeroelect wrote: > At 07:18 AM 8/29/2013, you wrote: > > > > Hi Bob > > > > The Europa that I am building uses a Ray Allen for pitch trimming. I have read over the years that some folks have the same problem you are experiencing when transmitting. It seems that the greatest success is keeping the wire run as far from antenna and associated wires as you can. I installed 5 conductor twisted with shielding from ACS: > > > > http://www.europaowners.org/main.php?g2_itemId=30484 (http://www.europaowners.org/main.php?g2_itemId=30484) > > > > Ron Parigoris > > After pondering schematics for the trim indicator, > the reason for it's sensitivity to RF becomes > apparent. The design was never evaluated and > crafted for immunity to RF interference. There > are critical components missing from the design. > > I note further that voltage used to excite the > potentiometer in the actuator is the rudimentary > 1.2 volts supplied by the internal reference > regulator. An excerpt from the LM3914 specifications > states . . . > > [img]cid:.0[/img] > > > A higher reference voltage increases noise immunity > for the A/D conversion and less jitter or uncertainty > in the bar-to-bar transitions for the display. I would > have considered at least a 5v reference and probably > some higher value still by adding R1/R2 as described > above. > > Referring to the data sheet again we see that bias (or > input load) current at the signal pin (5) is 100nA or > less. > > [img]cid:.1[/img] > > This means that we could put a resistor in series with > pin (5) of say 10,000 ohms and exert less than 1 millivolt > of error in the signal voltage. At the same time we would > add say 1000pF capacitor from pin 5 to ground (pin 2). > > This mod alone might fix the RF sensitivity problem. As > a matter of good design practice I would bypass the power > input pin (3) to ground as well. > > The designers also missed a great opportunity to make > their product truly 'universal' by not exploiting the > expanded scale voltmeter example in the specifications. > > > [img]cid:.2[/img] > > Adding a few components and a couple of pots would > allow the indicator to be tailored to a specific installation > such that full down trim would illuminate the bottom led, > full up trim the top led . . . irrespective of the actuator's > as-installed stroke. > > I offered to help these guys with this product line at > OSH about 20 years ago but they weren't interested. They > also appear to have learned nothing new by way of feedback > from the field as to how their product has been performing. > > Getting back to the original query for driving two indicators > from one actuator pot, a study of the schematics and data > suggests that two indicators running in parallel on one pot > will not significantly 'load' the signal. Hence, you can wire > one indicator to the actuator per installation instructions. > Then wire the second indicator wire for wire in parallel > with the first but leave its potentiometer excitation voltage > wire (orange) floating. > > Bottom line is that this indicator would benefit greatly > from due diligence to rudimentary operating characteristics > and limitations. Adding the resistor and capacitor described > above may fix the RF sensitivity issue. The idea that an > installer should be burdened with careful positioning of > wires to mitigate design flaws is decidedly un-cool. > > > > Bob . . . Hi bob. I have this problem. When I press the PTT the ray Allen led flickers and dims. I've read your post above but don't really understand what is need to rectify the problem. In the simplest of language how would I go about to resolve the problem? Many thanks Frank Read this topic online here: http://forums.matronics.com/viewtopic.php?p=463890#463890


    Message 2


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    Time: 03:49:32 PM PST US
    Subject: Trim position indicator
    From: "donjohnston" <don@velocity-xl.com>
    I'm looking for some idea on how to implement a trim position sensor. Attached is a picture of the aileron trim mechanism. DC motor on the right drives a cogged belt with an idler pulley on the left. There is no limiter on the motor. It can run continuously. When it is unable to pull the bellcrank, the belt begins slipping. The mechanism works fine. I'm not looking for a new trim mechanism. But I would like to know where the system is positioned. I thought about a small magnet on the belt and then some type of sensor but I think that would be too coarse. So I'm wondering if anyone has any ideas on how to implement a sensor. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=463896#463896 Attachments: http://forums.matronics.com//files/fff_small_544.jpg


    Message 3


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    Time: 04:32:25 PM PST US
    From: Matt Dralle <dralle@matronics.com>
    Subject: Re: Trim position indicator
    Hi Don, I think you want one of these: https://www.aircraftspruce.com/catalog/elpages/racpos12sensor.php?clickkey=35250 [] At 03:48 PM 12/13/2016 Tuesday, you wrote: > >I'm looking for some idea on how to implement a trim position sensor. > >Attached is a picture of the aileron trim mechanism. > >DC motor on the right drives a cogged belt with an idler pulley on the left. There is no limiter on the motor. It can run continuously. When it is unable to pull the bellcrank, the belt begins slipping. > >The mechanism works fine. I'm not looking for a new trim mechanism. > >But I would like to know where the system is positioned. I thought about a small magnet on the belt and then some type of sensor but I think that would be too coarse. > >So I'm wondering if anyone has any ideas on how to implement a sensor. > > >Read this topic online here: > >http://forums.matronics.com/viewtopic.php?p=463896#463896 > > >Attachments: > >http://forums.matronics.com//files/fff_small_544.jpg > Matt G Dralle | Matronics | 581 Jeannie Way | Livermore | CA | 94550 925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email http://www.matronics.com/ WWW | Featuring Products For Aircraft


    Message 4


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    Time: 04:52:18 PM PST US
    From: Alec Myers <alec@alecmyers.com>
    Subject: Re: Trim position indicator
    how about a servo potentiometer geared to the idler pulley On Dec 13, 2016, at 19:30, Matt Dralle <dralle@matronics.com> wrote: Hi Don, I think you want one of these: https://www.aircraftspruce.com/catalog/elpages/racpos12sensor.php?c lickkey=35250 At 03:48 PM 12/13/2016 Tuesday, you wrote: m> > > I'm looking for some idea on how to implement a trim position sensor. > > Attached is a picture of the aileron trim mechanism. > > DC motor on the right drives a cogged belt with an idler pulley on the lef t. There is no limiter on the motor. It can run continuously. When it is un able to pull the bellcrank, the belt begins slipping. > > The mechanism works fine. I'm not looking for a new trim mechanism. > > But I would like to know where the system is positioned. I thought about a small magnet on the belt and then some type of sensor but I think that woul d be too coarse. > > So I'm wondering if anyone has any ideas on how to implement a sensor. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=463896#463896 > > > > > Attachments: > > http://forums.matronics.com//files/fff_small_544.jpg > Matt G Dralle | Matronics | 581 Jeannie Way | Livermore | CA | 94550 925-606-1001 V | 925-606-6281 F | dralle@matronics.com Email http://www.matronics.com/ WWW | Featuring Products For Aircraft


    Message 5


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    Time: 05:43:55 PM PST US
    Subject: Re: Trim position indicator
    From: "donjohnston" <don@velocity-xl.com>
    Hey Matt, I thought about that. But since this isn't a linear mechanism, I couldn't figure out how to implement that sensor. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=463899#463899


    Message 6


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    Time: 06:34:17 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Trim position indicator
    > > >But I would like to know where the system is positioned. I thought >about a small magnet on the belt and then some type of sensor but I >think that would be too coarse. > >So I'm wondering if anyone has any ideas on how to implement a sensor. Emacs! There's a family of ten-turn potentiometers. You might be able to couple one of these to your idler pulley. See http://tinyurl.com/gunkre5 Bob . . .


    Message 7


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    Time: 06:52:46 PM PST US
    From: ashleysc@broadstripe.net
    Subject: Re: Trim position indicator
    Hi Don Johnston; Ray Allen makes a trim position sender that you could actuate by anchoring one end and fastening the other to the crank arm. It will not send a "stop" signal to the trim motor, so you will have to provide some other method of limiting the stroke of the trim motor. Cheers! Stu. ----- Original Message ----- From: "donjohnston" <don@velocity-xl.com> Sent: Tuesday, December 13, 2016 3:48:24 PM Subject: AeroElectric-List: Trim position indicator I'm looking for some idea on how to implement a trim position sensor. Attached is a picture of the aileron trim mechanism. DC motor on the right drives a cogged belt with an idler pulley on the left. There is no limiter on the motor. It can run continuously. When it is unable to pull the bellcrank, the belt begins slipping. The mechanism works fine. I'm not looking for a new trim mechanism. But I would like to know where the system is positioned. I thought about a small magnet on the belt and then some type of sensor but I think that would be too coarse. So I'm wondering if anyone has any ideas on how to implement a sensor. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=463896#463896 Attachments: http://forums.matronics.com//files/fff_small_544.jpg


    Message 8


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    Time: 07:20:22 PM PST US
    Subject: Re: Trim position sensor
    From: "user9253" <fransew@gmail.com>
    If you fastened a magnet to the belt, mount many magnetic reed switches side by side (glass touching glass) so that at least one switch will always be activated. 25 switches (part number 934-FLEX-14-20-25) cost about $10 total at Mouser. Reed switches are most easily activated when the magnet is parallel to the switch. In other words, the magnet north pole is near one end of the switch and the south pole is near the other end of the switch. A bar magnet should lay flat on the belt with its axis perpendicular to the length of the belt. Perhaps others can design a circuit to convert switch closure to panel display. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=463902#463902




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