Today's Message Index:
----------------------
1. 05:19 AM - Re: Sequential turn signals...OFF TOPIC (Trampas)
2. 05:41 AM - Re: special progressive (Chad Robinson)
3. 08:25 AM - Re: Load dump issues (Paul Messinger)
4. 01:35 PM - Re: special progressive (flmike)
5. 03:44 PM - Radio headset noise (Scott Hersha)
6. 03:44 PM - headset noise (Scott Hersha)
7. 07:27 PM - Re: Mag Headings (Speedy11@aol.com)
8. 08:20 PM - Re: Toggle switches (Speedy11@aol.com)
9. 08:28 PM - Contactor replacement (Speedy11@aol.com)
10. 11:24 PM - Antw: Re: round transponder recommendations (Alfred Buess)
Message 1
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| Subject: | Sequential turn signals...OFF TOPIC |
--> AeroElectric-List message posted by: "Trampas" <tstern@nc.rr.com>
You can do it with two 555 timers.
What happens is when the turn signal wire is activated, the first light is
lit and the first 555 timer starts, when it times out the second light is
lit and the second 555 timer starts, then when it times out the third light
is lit.
This is assuming the turn signal currently has a long enough "on" time. If
it does not then, you can use another 555 as a flasher, which would enable
you to set your on to off time.
Personally, however, I would not use 555 timers, as that it is complicated.
Instead I would use a cheap Microcontroller like the PIC. These
microcontroller are almost as cheap as a 555 timer and gives you lots more
flexibility.
Regards,
Trampas Stern
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Chris
Adkins
Subject: AeroElectric-List: Sequential turn signals...OFF TOPIC
--> AeroElectric-List message posted by: "Chris Adkins"
<ccadkins@adelphia.net>
I know, I know...this is TOTALLY off subject...BUT...
What are all the "kiddies" using to pull off the "sequential turn
signals" trick on their cars? I can remember the days when the only way
to do it was with a geared dc motor driving a little cam which depressed
some reed switches. I'm sure it's much more elegant than that NOW, and
I'm just wondering if any of you guys know how it's done! (BTW, I have
selfish reasons too...I want them on my '88 Buick Reatta, but don't
wanna' pay $59 for the kit on Ebay).
Chris
Message 2
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| Subject: | Re: special progressive |
--> AeroElectric-List message posted by: Chad Robinson <crobinson@rfgonline.com>
Troy Scott wrote:
> --> AeroElectric-List message posted by: "Troy Scott" <tscott1217@bellsouth.net>
>
> Gentlemen,
>
> Is there a three-position progressive switch made so the upper two positions
> are progressive, but the bottom position is only on when the switch is in
> the bottom position? Like this:
> Top Position: middle and upper positions on
> Middle position: only the middle position is on
> Bottom position: only the bottom position is on
I haven't seen one, but you can make it yourself with a SP3T or DP3T switch
and a diode. Just put a diode between the top and middle position connectors
with the band on the diode toward the middle connection. In the top position
the diode will allow current to flow to both the top and middle wires. In the
middle position the middle will be on, but the diode will block current from
flowing to the top. And the bottom is the bottom.
A Schottky diode of reasonable size is probably a wise idea if you plan to run
any significant current from the MIDDLE position - the devices on the top and
bottom don't affect this need.
Regards,
Chad
Message 3
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| Subject: | Re: Load dump issues |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
George has made general comments and I am sure at least some of us would be
interested in specific test results. I am NOT questioning what he has said,
but I am interested in what he has tried that did not work.
As for Jerry's comments consider the following.
First I agree the use of a single 1,500W TVS is not enough for worst case
load dump control, but the 5,000W units seem to be adequate (at least in
terms of the TVS power rating) for a 50A single event load dump (and it is a
single event dump producing a high voltage pulse that we are concerned with)
Any long duration event is taken care of with the OVP unit. Thus the TVS and
OVP devices work in combination to prevent systems damage from over voltage.
I have tested 1,500 watt units and verified that they can load clamp 10 amps
long enough to blow a 5 amp circuit breaker (much longer that a load dump
event). Not sure all mfgrs of similar devices will do this but after 10
tests of the same part no damage or change in part charactericts were noted.
A load dump event is NOT a failure of the alternator. Unlike the HI voltage
from a failed regulator that is controlled by the OVP unit. Load dump is the
result of: operator, circuit design, or contactor failure that allows the
alternator to become suddenly unloaded.
Operator error can be reduced with locking lever switches etc.
Circuit design can prevent operator error but introduces other issues.
Contactor failure is something that can happen and this is where something
needs to be done so a single failure does not cause another failure. First
failure is the contactor failing. The next failure is an uncontrolled load
dump that damages one or more of the following devices, Alternator diodes,
alternator regulator, and or avionics etc. on the connected busses in the
aircraft.
No single failure should cause secondary failure, if at all possible, thus
the current discussion of load dump control.
The TVS diodes are NOT intended to protect long HV events and in the case of
long HV events the OVP unit will do the job by disconnecting the alternator
in a few ms which is longer than the load dump event and is short enough to
prevent damage to the Load dump TVS (in other cases where HV is produced)
which reduces the load dump voltages while the OVP unit is disconnecting the
alternator.
The voltage does increase above the TVS rated voltage as the current
increases. For example the 500amp unit designed for load dump I have
mentioned has a voltage well over 50V during peak current conditions. While
this is far less that a non-clamped voltage its too high for our equipment.
So while the regulator in the alternator and the alternator diodes are
protected our avionics are not.
This is because the load dump condition passes thru the "B" lead to the main
bus before the contactor in the "B" lead releases from the OVP device, for
internal regulators, and removing field power on external regulators. As the
load dump energy is already in the alternator and must go somewhere
additional protection is needed.
5kw 18v TVS units are available and are rated at over 150 amp single event
pulse.
So perhaps putting several units in parallel is a practical solution. I
agree that this is best done with matched devices but consider the
following. The real conservative person decides that 3 units in parallel
with be enough. Also for this discussion that the current being shunted by
each unit has a current to voltage increase of 1V for every 10 amps of shunt
current. These are not real values but used to make my point.
So clamp voltage for each unit is assumed to be 18V, 19V, and 20V for the
units.
The first unit sees the load sump and starts clamping at 18v. As the load
current voltage gets to 19v (10 amps) the second unit starts clamping. As
the voltage still increases the third unit starts clamping.
Now at 21V the first unit is clamping 30 amps, the second unit is clamping
20 amps and the third unit is clamping 10 amps and the bus voltage is
clamped at 21v for a 60 amp load. No matching of devices was needed in the
above example with available tolerance units.
Use of an adjustable current limited power supply would allow matching at a
current of say 1-10 amps which is within the current rating depending on the
device for steady state currents and only a few seconds is really needed to
measure the voltage at the test current. Buying 10 units (at under $1 each)
is likely to produce several well matched units so the load sharing is much
better than my example above.
However the clamped voltage of 21V (in the above example) is higher than the
OVP design of perhaps 16V and may be higher that the max rated voltage of
the some avionics and either a different approach and or additional
protection may be needed.
The widely available 1,500w units can be used but will require more units to
keep the voltage peak to the desired design limit with current sharing.
The preceding is just one solution. However use of TVS devices must be done
carefully to consider not just the power pulse rating but the peak
suppressed voltage which is device and current dependent.
Keeping the BUS voltage under 20V is not easy with a 50a load dump.
The large capacitor I mentioned earlier is also a possible alternative IF
the selected capacitor is designed for low internal resistance at hi
frequency. Again some design is needed to see how well this may work.
Paul
----- Original Message -----
From: "Jerzy Krasinski" <krasinski@direcway.com>
Subject: Re: AeroElectric-List: Load dump issues
> --> AeroElectric-List message posted by: Jerzy Krasinski
<krasinski@direcway.com>
>
>
> George Braly wrote:
>
> >--> AeroElectric-List message posted by: George Braly <gwbraly@gami.com>
> >
> >
> >Bob,
> >
> >I have done a fair amount of testing a couple of years ago, working with
the
> >TVS devices, including the larger sized versions.
> >
> >In my experience, they have not been adequate, alone, to prevent over
> >voltage spikes on load dumps, even from smaller alternators.
> >
> >They help. But I have blown some of them on load dumps.
> >
> >Regards, George
> >
> >
> >
> >
>
> I am not surprised. Looking at the data for 1500W devices we find the
maximum pulse is 1ms at half peak value current. That is much shorter than
the expected alternator pulse.
>
> The non repeatable surge current is listed as 200A for 50 ms. Probably
more likely peak current would be around 50A, so that would allow some
extension of the pulse length. But that is for a nonrepeatable event.
>
> That shows that for the alternator full current application they are
beaten at the the surge limits.
>
> Connecting TVS devices in parallel is a waste. Their characteristics
differ enough so most of the current will go through one TVS, while others
will just hang there. Maybe measuring them and selecting them in very
similar bunches would work, but that requires building a nonstandard curve
tracer for operation at rather high currents. Probably it can be done in a
crude way discharging a capacitor through a few of them in parallel and
observing the currents on a multichannel scope.
>
> One can easy increase the power to 3000W by connecting in series two 6.8V
devices. Unfortunately, 6.8V is the lowest voltage TVS I found, and that
increases power only by a factor of two. But if in your experiments they
failed only sometimes, that factor of two might be everything we need.
>
> Jerzy
Message 4
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| Subject: | Re: special progressive |
--> AeroElectric-List message posted by: flmike <flmike2001@yahoo.com>
The C&K 7211 might do what you want. It is a
miniature toggle though.
Mike
__________________________________
http://taxes.yahoo.com/filing.html
Message 5
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| Subject: | Radio headset noise |
--> AeroElectric-List message posted by: "Scott Hersha" <shersha@fuse.net>
I've been working on eliminating noise in my headset, and here's what I found.
I have a new RV-6 and I'm using the DC laodcenter bus system with the backup
battery bus option. I had noise from my strobes, fuel pump, an alternator hum,
and a low level hum from most anything that you turned on. This could be heard
clearly using a noise canceling headset, not so clearly (except the strobe
noise) using a passive headset. I built 3 noise filters described by Bob Nuchols
on his site, two for my two strobe power supplies, and one for my audio panel
amp, which I built myself using Radio Shack parts. I was able to determine
most of the noise was coming from my bus, and not being picked up on my antenna
systems(I have 2 COM radios). I installed the filters on the strobes first
and I noticed a reduction in strobe noise. I could still hear it, but it wasn't
as harsh. Then I installed the third filter on my audio amp and it became
very silent. There is virtually zero noise. T!
he only problem is there is very little volume left from my COM radio. With the
volume all the way up at max, I can barely hear it. The question I have for
anyone out there and Bob when he gets back is, would a smaller capacitor in the
filter prevent losing so much gain on my radio? The plans Bob wrote call for
a 10uf capacitor to be used with the inductor coil, but the kit from Radio
Shack came with a 220uf capacitor. Will that have an affect on radio volume?
I probably need to make another one with a smaller capacitor or maybe connect
the filter to my radio/intercom instead of the audio amp. Looking for advice.
> Scott Hersha
>
Message 6
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--> AeroElectric-List message posted by: "Scott Hersha" <shersha@fuse.net>
I bought an alternator filter/capacitor from Aircraft Spruce. It was kind of
expensive, about $39.00, but it worked for me.
> Scott Hersha
>
Message 7
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| Subject: | Re: Mag Headings |
--> AeroElectric-List message posted by: Speedy11@aol.com
Okay, niceez, you've launched two unprovoked attacks on me so I intend to
stand up for myself and, in the future, ask you to use restraint in your attacks.
All of my comments here are in reference to your post which is shown below.
Runway headings do change over time due to changes in the earth's magnetic
field. Runway 12 at Houston's Hobby Airport has a mag heading of 129.
When you say you don't like my method that is non-compliance with IFR and VFR
regulations, I have no idea what "method" of mine you're talking about. I
haven't suggested any method. And you can take your condescending tone (you
need to look it up yourself so you'll remember it next time and I won't have to
be bothered with you again) and shove it..
I haven't read any suggestions on this list that pilots should depend 100% on
GPS for navigation. Personally, I will not permit students to use GPS until
after their checkride. Then I will teach GPS. Since I charge nothing for
instruction, I'm not just trying to gouge students for more money. I believe GPS
is an aid to navigation that is incredibly valuable, but it is one which must
be expendable.
I missed your point (assuming there was one) when you pointed out that the
DC-9 had a reverse view mag compass. Perhaps you're giving an example of
required equipment.
It was good to hear the gospel according to the Canard-Aviators group. I'd
like to talk to the controllers in the group. I've never heard of a controller
giving two headings and then, if upset, tell a pilot to "get lost," in so
many words.
Dale, you attempt to talk like an expert - in something - but I'm not
convinced. I don't profess to be an expert in aviation, but some of my credentials
are listed below.
I'd appreciate it if you sent your attacks on me directly to me
(speedy11@aol.com) instead of posting them on this list. I am more than willing
to debate
off list. From now on, if I have something to say to you, I won't use list
time, I'll send it directly to you. I apologise to list members for this post,
but I'll only turn the other cheek once.
Stan Sutterfield, LtC Retired
RV-8A
Tampa
F-4, F-5, F-16, B-737, too many experimental and light aircraft to list
CFI
In a message dated 2/15/04 2:57:07 AM Eastern Standard Time,
aeroelectric-list-digest@matronics.com writes:
<< Runway headings change with the earth magnetic field and runways headings
> are permitted to be off as much as 5. I mean if divisions for runway
> headings are every 10 there has to be some room for error. For one I
don't
> like Speedy11's method and it doesn't comply with regs for VFR or IFR
> flight. I won't quote FAR Part 91 as looking it up ourselves is a part of
> continuing education we all need and if I were to tell you - you wouldn't
> remember it (As now?).
>
> All Gyro's precess and need correction including Slaved units. Relying on
> GPS for sole navigation 100% of the time is nuts and illegal in some
cases.
>
> Further to use the "system" you are required to have the appropriate
> equipment on board. I recall an airliner which had the Mag compass behind
> both pilots but centered in the airplane and facing forward (not kidding)
> and to use it would look up at a mirror to see it.
>
> We had a similar discussion on the Canard-Aviators group last month about
> GPS ground track verses mag heading and the current and ex-ATC controls in
> the group spoke up and said if you turned to a heading and the controller
> didn't like he would add more correction to your course and if it upset
> him/her you would here - "Flight advisories/following is canceled - squawk
> VFR - Good day" >>
Message 8
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| Subject: | Re: Toggle switches |
--> AeroElectric-List message posted by: Speedy11@aol.com
Eric,
I've been looking for the F-16 toggle switch guards. But I can't afford
those prices! Guess I could make my own. They are so simple and lightweight I'm
surprised someone (like you) hasn't been producing them. I'll take a look at
your other switches.
Stan
In a message dated 2/15/04 2:57:07 AM Eastern Standard Time,
aeroelectric-list-digest@matronics.com writes:
<< By the way--I used to sell F-16 V-max toggle switch guards on my website. I
was buying them at $3.00 each. Then the wholesale price went to $40 each
with a minimum buy of 50 pcs. One piece wholesale price $130. They hand
paint them in France...I was told. M'aidez!
By the way2--I had in my hands an actual real genuine (titanium) Space
Shuttle Switch Guard, thanks to Historic Space Systems (www.space1.com) and
with the magic of CNC and the original Rockwell blueprints they are on my
website too (in hard anodized aluminum). >>
Message 9
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| Subject: | Contactor replacement |
--> AeroElectric-List message posted by: Speedy11@aol.com
Eric,
What is the status of your
1280 Peak Amp Contactor "Powerlink". Still in testing, it will soon eliminate
5 pounds of those big hand-grenade-sized contactors.?
Stan Sutterfield
Message 10
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| Subject: | Re: round transponder recommendations |
--> AeroElectric-List message posted by: "Alfred Buess" <Alfred.Buess@shl.bfh.ch>
There is an other option available: TRT600 or TRT800 from Filser. Not cheap, but
Mode S capable (will soon be mandatory in Europe!) and integrated blind encoder.
Have a look at
http://www.filser.de/
Alfred Buess
>>> richard@riley.net 02/14 3:28 >>>
--> AeroElectric-List message posted by: richard@riley.net
At 07:15 PM 2/13/04 -0600, AI Nut wrote:
>--> AeroElectric-List message posted by: "AI Nut" <ainut@earthlink.net>
>
>Anyone have a recommendation for a round transponder to fit into the panel?
>Cheap is good!
>I've heard some bad news about the one from Austraila.
The only other one is the Becker.
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