Today's Message Index:
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1. 10:21 AM - Re: Motor reversing circuit for trim servo motor using automotive relays (Bob Verwey)
2. 04:35 PM - Re: Non Aviation 2 ()
3. 04:43 PM - Re: Motor reversing circuit for trim servo motor using automoti (user9253)
4. 05:19 PM - Simple sequencing using common 5-pin auto relays (Matthew S. Whiting)
5. 07:08 PM - Re: Simple sequencing using common 5-pin auto relays (Eric Page)
6. 08:05 PM - Re: Simple sequencing using common 5-pin auto relays (Eric Page)
Message 1
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| Subject: | Re: Motor reversing circuit for trim servo motor using |
automotive relays
This is a well tested solution on LSA airplanes in our part of the world.
Small trimtab makes it unlikely that a runaway event or mechanical
disconnect will lead to catastrophic failure. Furthermore, these airplanes
are for day VFR use only.
The unit is a simple 2 wire system and robust, with internal travel limit
switches.
[image: Trim tab actuator.jpg]
On Mon, 7 Aug 2023 at 01:55, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 12:31 PM 8/5/2023, you wrote:
>
> charlesdavis@iuncapped.co.za>
>
> Bob, could you share some details on the actuator and how you implemented
> the fit, please .... I need to achieve something similar to this for a
> Whisper TMG.
>
> Thanks, Charles
>
>
> I've not been involved in crafting such an
> installation in a light plane. I have worked
> on controls and components for trim actuator
> systems from Lear 55 down thru numerous light planes.
>
> I've had failure analysis tasks on several
> trim systems and I'm familiar with some
> of the requirements and risks.
>
> When I read that someone is considering or
> has accomplished a modification to a design
> with a demonstrated or certified history,
> little red flags pop up. Just be sure that
> the proposed system won't cut the stabilizer
> or tabs loose to flop in the breeze.
>
>
> Bob . . .
>
> ////
> (o o)
> ===========o00o=(_)=o00o========
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> ================================
>
> In the interest of creative evolution
> of the-best-we-know-how-to-do based
> on physics and good practice.
>
--
Best Regards,
Bob Verwey
082 331 2727
Message 2
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Thanks for all the help and suggestions.
Feel like a complete idiot, problem was a tripped breaker that I did not
know about, all well now
Mike
From: owner-aeroelectric-list-server@matronics.com
<owner-aeroelectric-list-server@matronics.com> On Behalf Of mike Pienaar
Sent: August 2, 2023 7:50 PM
Subject: AeroElectric-List: Non Aviation 2
Here is a picture of the back of the jack and where it attaches to the
board
What I cannot understand is that sometimes you had to jiggle it before
it
worked
Does not look like a normally closed switch
Thanks again for the help
Had to start a new thread, would not accept photo
Message 3
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| Subject: | Re: Motor reversing circuit for trim servo motor using |
automoti
Here is the website for the linear actuator pictured above by Bob Verwey.
https://www.linact.co.za/lite-duty-linear-actuators/#Micro_N2
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511201#511201
Message 4
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| Subject: | Simple sequencing using common 5-pin auto relays |
I have an idea that I am not sure how to implement or if it is even possible to
implement simply. I know it could be easily done using a microcontroller and
fairly easily done with a small PCB with a 555 timer and a few discrete components,
but I am wondering if this can be done using nothing but standard Bosch-style
auto relays. The application is the start sequence for a Rotax 915 that
needs to have start power provided for a short time until the engine revs past
1500 or so.
I know this can easily be done with two momentary contact switches, one for the
start power and the second to actuate the starter. However, this requires manually
operating both switches with one hand to keep the other on the throttle.
This can be made easier by mounting one switch where you can reach it with
your hand on the throttle, or mounting one as a toggle switch sideways that can
be pulled towards a guarded starter button using the guard as a place to pull
against while waiting for the Lanes to self-test before hitting the start button.
I am trying to decide if this can be done using two buttons operated in sequence.
Basically this is the sequence of operation:
Press button #1 - latch a relay to provide start power.
Release button #1 - NOP
Press button #2 - engages starter
Release button #2 - disengage starter AND unlatch the start power relay, possible
with a short delay, but it appears that the Rotax engine will rev past 1500
so fast that by the time a human releases the start button the engine is fine
also losing the start power supply.
I know how to latch a relay using two switches, one tNO to latch and another NC
to unlatch. What I am not sure how to do is to unlatch a latched relay using
the trailing edge of a momentary contact push button/switch.
Anyone done this or have an idea how to do it with just a relay or three?
Matt
Message 5
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| Subject: | Re: Simple sequencing using common 5-pin auto relays |
I don't know if it's possible to do it with two buttons and ONLY relays, but how
about using a single button, three SPDT relays, three diodes and a capacitor?
We can take advantage of the fact that relays will remain energized at voltages
significantly below their rated coil voltage to hold START POWER engaged
for a short time after the ENGINE START switch is released. See the attached
diagram.
When the ENGINE START button is pushed, all three relay coils are energized and
capacitor C1 is charged to battery voltage. The ENG STRTR relay will close a
few milliseconds before the two STRT PWR relays (due to charging C1), but that
may not make any difference if the Rotax Fuse Box needs to see START POWER before
it will engage the starter. That's an unknown.
When the ENGINE START button is released, diode D1 isolates the ENG STRTR relay
(K1) from the capacitor, so it drops out immediately. C1 discharges through
the coils of the two STRT PWR relays (K2 and K3), until the voltage falls to their
drop-out point. A capacitor of 4,700F should provide about half a second
delay, assuming the relay coil resistances are about 90 each and they drop out
at around 1.2V (values taken from a randomly selected automotive relay datasheet).
It would take some experimentation to find exactly the right value.
This was an interesting thinking exercise, but you implement my idea at your own
risk. Personally, I would stick with something very close to the Rotax installation
manual diagrams.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511203#511203
Message 6
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| Subject: | Re: Simple sequencing using common 5-pin auto relays |
Upon further reflection, I definitely would not do this. With a 9-Series iS engine,
you need to be able to engage the starter with the BACKUP BATTERY switch
closed in the event of dual charging system failure. In that case, you don't
want START POWER engaged as well.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=511204#511204
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