Today's Message Index:
----------------------
1. 06:46 AM - Re: Re: Looking for a circuit that when you press a button powers th (Robert L. Nuckolls, III)
2. 07:53 AM - Re: Re: Looking for a circuit that when you press a button powers th (Jeffrey Skiba)
3. 07:57 AM - Re: Re: Looking for a circuit that when you press a button powers th (Mike Welch)
4. 08:10 AM - Re: Re: Looking for a circuit that when you press a button powers th (The Kuffels)
5. 08:27 AM - Re: Re: Looking for a circuit that when you press a button powers th (The Kuffels)
6. 12:07 PM - Re: Re: Looking for a circuit that when you press a button powers th (Robert L. Nuckolls, III)
7. 02:07 PM - Re: Why does a master switch turn off devices? (Robert L. Nuckolls, III)
8. 03:28 PM - Re: Bad Crimp? (Vern Little)
9. 03:52 PM - Re: Why does a master switch turn off devices? (Robert L. Nuckolls, III)
10. 04:41 PM - Re: Why does a master switch turn off devices? (Robert L. Nuckolls, III)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
At 03:01 PM 9/14/2013, you wrote:
>
>Driving a servo max current would be 900 milliamps.
>
>
>.a circuit that will only be on for 3 seconds maximum, even if
>you're still holding down the button. If you let go early, it turns
>off early. Do I have that right? You GOT it
Okay, this conversation is an excellent example
of the $time$ that can be expended when the
participants in a discussion all have different
mental images of what's being asked . . .
If I understand your design goals correctly
you're wanting a trim motor run time limiter
that will trip for any motor command exceeding
3 seconds . . . but resets as soon as power
is removed. Hence, a series of trim commands
of 3 seconds or less will be conducted to
the motor without modification. A stick trim
switch would, therefore be limited in how far
the airplane could be driven out of trim
by the fault.
Do I presume correctly from the current draw
value that we're talking about a Ray-Allen
actuator? If so, then the motor to be controlled
is a permanent magnet device wherein direction
is determined by the polarity of applied voltage.
This fact does not preclude putting the run-limit
circuitry in the ground side of the supply power.
This narration also suggests that the timing
function need not be terribly accurate. A
specification of 3.0 +/- 0.5 seconds would
probably suffice . . . timer accuracy requirements
drive selection of components.
Is the narrative above accurate? The creative
designers need to know before serious sifting
of the ingredients suited to a recipe for
success.
Bob . . .
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
As usual Bob you are correct on all statements :-)
The one other item I would like to add is to also include a two speed function.
A slower rate of movement for the servo at a higher airspeed controlled by manual
switch or airspeed switch, vs the full rate of the servo at slow airspeeds
(pattern) again that portion could be store bought (ray allen speed control one
example but those are $45 each so building one at the same time as the original
requested circuit, I would think would be lots cheaper and I would learn
something about it in the process)
*Note I just found your drawing for two speed trim system but cannot find the Component "AEC9013-110-1 Speed Control" on your site any longer. Ref: http://www.aeroelectric.com/PPS/Flight/Trim/Two_Speed_Trim_2.pdf
Does this drawing show everything to build the speed controller ?
Sorry for wasting $time$ that can be expended when the
participants in a discussion all have different
mental images of what's being asked . . .
Thanks in advance for everyone's time
Jeff.
--> <nuckolls.bob@aeroelectric.com>
At 03:01 PM 9/14/2013, you wrote:
>--> <jskiba@icosa.net>
>
>Driving a servo max current would be 900 milliamps.
>
>
>.a circuit that will only be on for 3 seconds maximum, even if you're
>still holding down the button. If you let go early, it turns off early.
>Do I have that right? You GOT it
Okay, this conversation is an excellent example
of the $time$ that can be expended when the
participants in a discussion all have different
mental images of what's being asked . . .
If I understand your design goals correctly
you're wanting a trim motor run time limiter
that will trip for any motor command exceeding
3 seconds . . . but resets as soon as power
is removed. Hence, a series of trim commands
of 3 seconds or less will be conducted to
the motor without modification. A stick trim
switch would, therefore be limited in how far
the airplane could be driven out of trim
by the fault.
Do I presume correctly from the current draw
value that we're talking about a Ray-Allen
actuator? If so, then the motor to be controlled
is a permanent magnet device wherein direction
is determined by the polarity of applied voltage.
This fact does not preclude putting the run-limit
circuitry in the ground side of the supply power.
This narration also suggests that the timing
function need not be terribly accurate. A
specification of 3.0 +/- 0.5 seconds would
probably suffice . . . timer accuracy requirements
drive selection of components.
Is the narrative above accurate? The creative
designers need to know before serious sifting
of the ingredients suited to a recipe for
success.
Bob . . .
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
Bob N,
Didn't you already do this circuit for me two years ago, for that IvoProp electric
Prop controller?
Mike Welch
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
Jeff,
Exactly the circuit you describe for two axis trim and two pilot control was
published by me in the June 2013 Kitplanes magazine.
If you leave out the fancy external (safety feature) controls and the
variable speed capability the parts cost (including 8 amp relays) is less
than $15. This compares well with the commercial unit Stein mentioned.
If you don't have access to the Kitplanes Magazine E-Library I can email you
pdf files of the schematic and the perfboard layout as well as the Bill of
Materials.
Tom
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
Jeff,
<< The one other item I would like to add is to also include a two speed
function. >>
The circuit I published (June 2013 Kitplanes magazine) does that also. All
out full featured parts cost is $30 about 1/10th the TCW unit..
Tom Kuffel
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Looking for a circuit that when you press |
a button powers th
At 09:56 AM 9/15/2013, you wrote:
>
>Bob N,
>
> Didn't you already do this circuit for me two years ago, for that
> IvoProp electric Prop controller?
>
>Mike Welch
>
>
No, that was an electronic circuit breaker designed to
be more accurate (and adjustable). That's on my list
of things to become a product.
Bob . . .
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Why does a master switch turn off devices? |
At 02:17 AM 9/14/2013, you wrote:
I've never quite understood something about aircraft electrical
systems and I'm hoping someone here can enlighten me.
I've always flown under the impression that a primary purpose of the
master switch is to effectively connect/disconnect power from the
electrical bus, which in turns provides for the flight instruments
and other electrical devices in the cockpit. However, my question is
that since the alternator is typically connected on the bus side of
the master contactor (not the battery side), why doesn't the
alternator continue to provide electrical power to the bus while the
engine is running when the master is off? Or does it? I have to
admit to not ever having tried to switch off the master in flight,
but I've been under the impression that doing so should turn off the
electrical equipment - it's after all, a recommendation to turn off
the master in a forced approach.
To achieve a solid understanding of how and why various
are placed on the ship's control panel, it's useful if
not a mitigation of risk, to understand what the controls
do and why they're included.
The legacy short answer to your question comes out of FAR23
as follows:
Sec. 23.1361 Master switch arrangement.
(a) There must be a master switch arrangement to allow ready disconnection
of each electric power source from power distribution systems, except as
provided in paragraph (b) of this section. The point of disconnection must be
adjacent to the sources controlled by the switch arrangement. If separate
switches are incorporated into the master switch arrangement, a means must be
provided for the switch arrangement to be operated by one hand with a single
movement.
Okay. In times gone by, separate switches for battery(ies) and
generator(s) were located right next to each other such that a
downward stroke of two fingers or a 'crash bar' makes the electrical
system go to max-dark.
The infamous 'split-rocker' switch was birthed during the transition
from generators to alternators on the single engine aircraft in the
1960s time-frame. It was discovered that alternators often would not
come on line without having a battery on also to excite the field. It
was also common wisdom that unlike generators (that self-excited
and happily ran sans battery), it was good practice to make sure
that a battery was ON any time an alternator was ON.
Hence the infamous 'split rocker' switch seemed like a good idea . . .
it could be fitted with mechanical interlocking of the two rockers
such that you can operate battery only but any attempt to turn
the alternator ON would add the battery also . . . further, any
attempt to take the battery OFF would also shut down the alternator.
This bit of mechanical slight-of-hand is easily accomplished with
a progressive-transfer, ON-ON-ON toggle switch wired as shown
http://tinyurl.com/kdqwahq
and in many of the wiring diagrams in Appendix Z of the 'Connection.
Do you have a copy of the book?
(b) Load circuits may be connected so that they remain energized when the
master switch is open, if the circuits are isolated, or physically shielded,
to prevent their igniting flammable fluids or vapors that might be liberated
by the leakage or rupture of any flammable fluid system; and
(1) The circuits are required for continued operation of the
engine; or
(2) The circuits are protected by circuit protective devices
with a rating
of five amperes or less adjacent to the electric power source.
(3) In addition, two or more circuits installed in accordance with the
requirements of paragraph (b)(2) of this section must not be
used to supply a
load of more than five amperes.
(c) The master switch or its controls must be so installed that the switch
is easily discernible and accessible to a crewmember.
From the electrical diagrams I've seen, it would seem as though that
switching off the master while the engine is running should do
nothing other than disconnect the battery from the bus, which would
not prevent the alternator from continuing to power electrical devices . . .
It depends on who's diagrams you've seen and what
the designer calls a "master switch". Bottom line is
that for every significant power source there should
be a pilot controlled switch properly labeled as
to which source is being controlled.
. . . but instead merely remove the battery's ability to absorb
transients, etc.
Batteries are poor mitigators of bus noises and are
effective only in mitigation of LARGE transients like
energizing a hydraulic pump motor . . .
Wouldn't the alternator continue to supply its own field current once
it is already running, so long as the alternator switch remains on?
Yes, unless your MASTER is wired like many a single engine
airplane and the alternator is forced off with the battery.
The modern Bonanzas have separate battery and alternator
switches. It seems that the Bonanza alternators WILL self
excite so ganging the alternator and battery switches together
is not necessary.
I think I'm missing something pretty basic here. Any help would be
greatly appreciated!
Do you have a copy of the AeroElectric Connection? Electrical
system architecture and design goals are discussed at length.
Also, check out hte articles on http://aeroelectric.com for
further enlightenment.
Bob . . .
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
A few years ago, I had a strobe switch failure, and the terminals
charred. The root cause is thermal runaway:
A strobe power supply is a constant-power device. This means that if
there is resistance in the switch circuit, it will draw more current to
make up the different. This increased current makes the switch get
hotter, increasing resistance, and so on. Eventually everything gets
toasty and fails.
The root cause of this was found (and reviewed by Bob) to be loose
rivets on the Carling switches used in this application. After I
switched to Honeywell switches (and changed the charred fast-ons),
I=99ve had no problems. This loose rivet failure also occurred
in my landing light circuit and master switch.
Vern
From: Dave Saylor
Sent: Friday, September 13, 2013 2:36 PM
Subject: AeroElectric-List: Bad Crimp?
Bob,
Can you tell from the photo if this is this a poor crimp? It was
overheating on the back of a strobe switch. I recall Bill Watson had a
crimp fail on a strobe switch recently as well. The strobes were
occasionally intermittent but the wire near the terminal was always very
hot to the touch. The insulation was discolored too.
I changed the terminal and the last few inches of wire, and now all is
well. Nice and cool.
Any comments on the crimp would be much appreciated.
Dave Saylor
831-750-0284 CL
-------------------------------------------------------------------------
-------
No virus found in this message.
Checked by AVG - www.avg.com
09/13/13
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Why does a master switch turn off devices? |
At 02:17 AM 9/14/2013, you wrote:
I've never quite understood something about aircraft electrical
systems and I'm hoping someone here can enlighten me.
I've always flown under the impression that a primary purpose of the
master switch is to effectively connect/disconnect power from the
electrical bus, which in turns provides for the flight instruments
and other electrical devices in the cockpit. However, my question is
that since the alternator is typically connected on the bus side of
the master contactor (not the battery side), why doesn't the
alternator continue to provide electrical power to the bus while the
engine is running when the master is off? Or does it? I have to
admit to not ever having tried to switch off the master in flight,
but I've been under the impression that doing so should turn off the
electrical equipment - it's after all, a recommendation to turn off
the master in a forced approach.
To achieve a solid understanding of how and why various
are placed on the ship's control panel, it's useful if
not a mitigation of risk, to understand what the controls
do and why they're included.
The legacy short answer to your question comes out of FAR23
as follows:
Sec. 23.1361 Master switch arrangement.
(a) There must be a master switch arrangement to allow ready disconnection
of each electric power source from power distribution systems, except as
provided in paragraph (b) of this section. The point of disconnection must be
adjacent to the sources controlled by the switch arrangement. If separate
switches are incorporated into the master switch arrangement, a means must be
provided for the switch arrangement to be operated by one hand with a single
movement.
Okay. In times gone by, separate switches for battery(ies) and
generator(s) were located right next to each other such that a
downward stroke of two fingers or a 'crash bar' makes the electrical
system go to max-dark.
The infamous 'split-rocker' switch was birthed during the transition
from generators to alternators on the single engine aircraft in the
1960s time-frame. It was discovered that alternators often would not
come on line without having a battery on also to excite the field. It
was also common wisdom that unlike generators (that self-excited
and happily ran sans battery), it was good practice to make sure
that a battery was ON any time an alternator was ON.
Hence the infamous 'split rocker' switch seemed like a good idea . . .
it could be fitted with mechanical interlocking of the two rockers
such that you can operate battery only but any attempt to turn
the alternator ON would add the battery also . . . further, any
attempt to take the battery OFF would also shut down the alternator.
This bit of mechanical slight-of-hand is easily accomplished with
a progressive-transfer, ON-ON-ON toggle switch wired as shown
http://tinyurl.com/kdqwahq
and in many of the wiring diagrams in Appendix Z of the 'Connection.
Do you have a copy of the book?
(b) Load circuits may be connected so that they remain energized when the
master switch is open, if the circuits are isolated, or physically shielded,
to prevent their igniting flammable fluids or vapors that might be liberated
by the leakage or rupture of any flammable fluid system; and
(1) The circuits are required for continued operation of the
engine; or
(2) The circuits are protected by circuit protective devices
with a rating
of five amperes or less adjacent to the electric power source.
(3) In addition, two or more circuits installed in accordance with the
requirements of paragraph (b)(2) of this section must not be
used to supply a
load of more than five amperes.
(c) The master switch or its controls must be so installed that the switch
is easily discernible and accessible to a crewmember.
From the electrical diagrams I've seen, it would seem as though that
switching off the master while the engine is running should do
nothing other than disconnect the battery from the bus, which would
not prevent the alternator from continuing to power electrical devices . . .
It depends on who's diagrams you've seen and what
the designer calls a "master switch". Bottom line is
that for every significant power source there should
be a pilot controlled switch properly labeled as
to which source is being controlled.
. . . but instead merely remove the battery's ability to absorb
transients, etc.
Batteries are poor mitigators of bus noises and are
effective only in mitigation of LARGE transients like
energizing a hydraulic pump motor . . .
Wouldn't the alternator continue to supply its own field current once
it is already running, so long as the alternator switch remains on?
Yes, unless your MASTER is wired like many a single engine
airplane and the alternator is forced off with the battery.
The modern Bonanzas have separate battery and alternator
switches. It seems that the Bonanza alternators WILL self
excite so ganging the alternator and battery switches together
is not necessary.
I think I'm missing something pretty basic here. Any help would be
greatly appreciated!
Do you have a copy of the AeroElectric Connection? Electrical
system architecture and design goals are discussed at length.
Also, check out hte articles on http://aeroelectric.com for
further enlightenment.
Bob . . .
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Why does a master switch turn off devices? |
Oops, sorry for the double posting of Part I. Here's
the rest of the story about energy management switches
in an airplane whether or not they are called "master
switches".
Consider this part of FAR23.1361
(b) Load circuits may be connected so that they remain energized when the
master switch is open, if the circuits are isolated, or physically shielded,
to prevent their igniting flammable fluids or vapors that might be liberated
by the leakage or rupture of any flammable fluid system; and
(1) The circuits are required for continued operation of the
engine; or
(2) The circuits are protected by circuit protective devices
with a rating
of five amperes or less adjacent to the electric power source.
(3) In addition, two or more circuits installed in accordance with the
requirements of paragraph (b)(2) of this section must not be
used to supply a
load of more than five amperes.
This section goes to issues that took root in
OBAM aviation, the electrically dependent engine.
Some years back we began to consider and expanded role
for the BATTERY BUS in powering electronic ignition
systems and/or fuel pumps necessary for engine operation.
The combination of switches one might call 'masters'
is set apart from engine critical circuits. For crash
safety, the FAA has embraced a "5A max" always hot
feeders for a variety of tasks not the least of which
was engine support. Paragraph (b)(3) seems to suggest
that the sum total of power feeders taken directly
from the battery bus should not exceed 5A . . . not
sure of how this might be interpreted by the
regulatory guru's I've known.
Since FAR23 does not apply to our endeavors (at least
not today) then the significance of (b)(3) is moot.
Nevertheless, battery bus feeders greater than 5A
might best be fitted with a disconnect relay at the
bus . . . not unlike Figure Z-32
http://tinyurl.com/756ydec
where it is shown as an auxiliary feed path to the e-bus.
That same relay might power a fuel injection pump
and be fused at much greater than 5A.
The point of this semantic hat dance is to illustrate
the wide range of power control switches that might
find their way onto the panel of an airplane and to
emphasize the fact that they might be called something
other than a 'master switch'.
Irrespective of what the switch is called, legacy
design goals for making the electrical system go max-dark
with a minimum of effort/confusion at the pilot's
discretion is worthy of the builder's consideration
Bob . . .
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|