Today's Message Index:
----------------------
1. 10:20 AM - Re: Engraved overlay and S700-2-10 terminals (Ken)
2. 10:20 AM - Solid State Relays vs. Solenoids (chad-c_sip@stanfordalumni.org)
3. 10:25 AM - Re: Load Analysis (details) (Walter Tondu)
4. 11:16 AM - Re: Cessna SB on transients. (Robert L. Nuckolls, III)
5. 10:51 PM - Re: HF meters (Hal Kempthorne)
6. 10:55 PM - Odyssey battery hold-down in an RV-8 (czechsix@juno.com)
7. 11:17 PM - Re: Solid State Relays vs. Solenoids (Robert L. Nuckolls, III)
8. 11:24 PM - Re: Engraved overlay and S700-2-10 terminals (rv-9a-online)
9. 11:37 PM - Panel vs Firewall Ground--do the electrons care? (Roger Evenson)
Message 1
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| Subject: | Re: Engraved overlay and S700-2-10 terminals |
--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
I am quite happy with white letters on clear TZ tape from a brother
P-touch. The panel is painted medium gray. Once applied and pressed
down, it is difficult to remove them without pulling the paint away too.
I used half inch tape which on a 1180 model (about $40. on sale) which
allows two lines of text if desired. Unlike lettraset the labels can
easily be applied after the panel is installed and populated.
Ken
RURUNY@aol.com wrote:
>--> AeroElectric-List message posted by: RURUNY@aol.com
>
>I'm drilling holes for the switches at this time and noticed that the
>S700-2-10 switch from B&C I'm using for the Master (OFF/BATT/ALT) has the upper
>left terminal marked 1 looking from the rear with the keyway up. Z-16 shows
>number 1 at the bottom left terminal in the same orientation. Should I use the
no
>1 on the switch?
>
>The post below shows a post from Bob in Jan in response to a switch keyway
>question.
>My question here is where are engraved overlays for switch labeling
>available, are they custom or do it yourself kits?
>My plan for labeling after panel drilling is complete is to paint it with
>dark grey rustoleum,
>use rub on transfer letters and numbers from Tower Hobbies, then use
>rustoleum flat clear
>over panel. Any better sugestions within a reasonable budget other than
>stickers from a label
>maker?
>
>Thanks
>Brian
>_http://www.zenithair.com/bldrlist/profiles/bunruh/_
>(http://www.zenithair.com/bldrlist/profiles/bunruh/)
>
>
>
>>I strongly suspect mounting the washer on the front side of the panel is
>>best, but am wondering if anyone has tried putting them on the back side.
>>
>>
>
>- I always put them on the back side. If your switch panel includes
>- an engraved overlay, then holes in the panel for the tabs can go
>- all the way through . . . and tabs on washers sanded to insure they
>- are flush or under flush to the panel surface. Others have suggested
>- a rear overlay of sheet metal but I prefer the engraved overlay for
>- switch labeling that covers the tab holes in the panel.
>-
>- Bob . . .
>
>
>
Message 2
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| Subject: | Solid State Relays vs. Solenoids |
Z-USANET-MsgId: XID494JeXe4X0393X31
1.25 RCVD_NUMERIC_HELO Received: contains an IP address used for HELO
--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
Can anyone give me pros and cons of using solid state relays instead of
solenoids for driving large current loads (lights, A/C compressor/hydraulic
pump, etc.). I've used Crydom SCRs in the past for switching AC systems. I'm
wondering if I couldn't use something like this:
http://www.crydom.com/userResources/productFamilies/40/crydom_d06d.pdf to
trigger my high-current loads.
I'll still get transient spikes from switching inductive loads on the
downstream side of the relay. But I shouldn't get the spikes on the bus-feed
side of the relay as I would with a solenoid. Is that correct? I'd appreciate
any input. I've got to make a decision about how I want to wire these loads up
in the next day or three.
Thanks.
Chad
Chad Sipperley
Lancair IVP - turbine (under construction)
Phoenix, AZ
Message 3
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| Subject: | Re: Load Analysis (details) |
--> AeroElectric-List message posted by: Walter Tondu <walter@tondu.com>
On 05/23 1:25, Hinde, Frank George (Corvallis) wrote:
> Thanks for the list Jim,
> Can you tell me...Have you actually measured the current drawn by the
> fuel pump?...I am planning a dual electric fuel pump (no mechanical
> pump) and was wondering if the SD-8 had enough oomph to run an Emag and
> and one fuel pump at minimum.
If you are talking about the Airflow Performance fuel pump
(http://www.airflowperformance.com) that Vans sells with their
kits you should amend your numbers to show a 7A draw for this pump.
This number comes directly from the fine folks there. I have not
measured it directly.
[...]
> BATTERY BUSS
> Main Battery Contactor (1A)
> Fuel Pump (4A - intermittent) <---
> Starter
> Starter Contactor (1A - Intermittent)
[...]
--
Walter Tondu
http://www.rv7-a.com
Message 4
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| Subject: | Re: Cessna SB on transients. |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>This is from 2002 ForPilots.com. I think it is of general interest to the
>discussion.
>
>My question is--Where do I get an online copy of the SB?
>
> > >(Mike wrote):
> > >The key to eliminating spike-induced damage to avionics and/or the OVP/VR
> > >is having said equipment off line at the instant the spikes are
>generated,
> > >and also by installing "catch" diodes across the starter and master
>solenoids,
> > >as well as having a "transorb" (MOV or Zener) across the main bus...
This is the standard mantra being propagated for over 4 decades.
Just enough science stirred together with lots of conjecture
to give it credibility.
> > Peter wrote:
> > Is there a US STC for these devices? Or are any "FAA-certified"? I am
> > in the UK and cannot do anything although if there is a STC the UK CAA
> > respects that (in trivial mods like this).
>
> >Cessna realized that they screwed up by producing aircraft from
> >the 1950s thru the 1980s with no catch diodes across the master,
> >starter, and external power solenoid, and they issued Service
> >Bulletins instructing owners to install a Cessna Part
> >No xxxxx diode(s) across the coils of the solenoid(s).
> >As I recall, the diodes turned out to be 1N4007...
"Screwed up"???? Cessna, like every other light airplane
company of the era installed the same components in their
airplanes as Ford and Chevy did in their cars. There was
no reason to treat the airplane different than any other
vehicle fitted with engine, generator/alternator and battery.
Until solid state devices showed up in airplanes in the early
60's there was no reason to be concerned or even investigate
inductive spikes from contactors. The radios were vacuum tube
and got high voltage from vibrator or dynamotor supplies. There
were no systems in the airplane that even MIGHT be vulnerable
to short duration, low energy transients.
> >My mechanic installed the diode per the service bulletin instructions
> >and maked a log entry "complied with SBxxxx" in the airfame log.
>
> >In the US, an AP mechanic can also make a "minor" mod, like adding a
> >transorb or a catch diode, and just make a log entry to return the
> >aircraft to service. My mechanic let me install other spike
> >catching components, and then just took care of the logs.
>
> >The spikes I recorded in my 1968 Skylane (14V) during cranking,
> >(prior to installing a catch diode across the starter solenoid)
> >were more than 400 V peak to peak, sort of a highly-damped sine
> >wave, that lasted about 10msec. My Skylane came out of the factory
> >with a catch diode on the master solenoid, but not on the aux
> >power solenoid or the starter solenoid.
Measured where? I've measured and demonstrated the high
voltage spiking capability of contactors and written about them
in detail. See:
http://aeroelectric.com/articles/spikecatcher.pdf
This same article speaks to the error in an original issue
of an AD against the ACS/Gerdes 510 ignition switch where
the diode was installed in the wrong place to protect the
switch. I note that later issues correct this error. I need
to update that article.
I was at Cessna when our chief scientist, Dr. Gordon Wood
purchased a brand new, Hewlett-Packard peak reading voltmeter.
We were all amazed at readings we got off the coils of starter
and battery master contactor coils. Gordon's work prompted us
to research available silicon diodes and device suitable means
for installing them on production aircraft. I seem to recall the
little 1N2070 plastic "bullet" being selected to install on strip
of phenolic with eyelets in each end to facilitate attachment of
PIDG terminated wires with screws. See . . . even in 1965 we were
wrestling with those little leaded critters to figure out a
good way to mount them.
So, the statement about Cessna's "screw up" is a product of
somebody's uninformed rhetoric. What the author does not point
out and Gordon Wood measured was that such spikes DO NOT propagate
to the bus. Yes, we could put the voltmeter on the un-suppressed
contactor coil and get readings that would impress even Nicky Tesla
but those energies were dissipated 99%+ in arcing at the
controlling switch. Remnants that showed up on the bus were very
short (microseconds), heavily loaded by system dynamic impedance
consisting of battery, capacitors on inputs to electronics, and
any equipment turned on, etc.
We knew in 1965 that starter and battery master contactor
spikes were not a risk to any other parts of the airplane
beyond the controlling switches. We also knew that bus
voltage transients due to starter activity were well inside
the range of bus voltages expected by the designers of the
radios.
Capacitors charged up to some value and then discharged to
a bus can deliver LOTS of current for a short time but a a
voltage no higher than they were charged with in the first
place. Inductors can deliver LOTS of volts for a short time
but at a current no greater than they were initially charged
with. Okay, it takes a 1A source to close a battery contactor.
Discharging a short (milliseconds), 1A constant current source
of any voltage into the bus is a non-event. Starter contactors
are a bit meaner, perhaps 4-5 amps. But still, no big deal with
a battery on line.
The NUMBER ONE reason for installing catch diodes was to
protect switch contacts and not to save overly delicate avionics
from the occasional transient that was WELL inside DO-160 limits.
I am still looking for the repeatable experiment that demonstrates
even a small fraction of the risks and worries that are freely
circulated amongst folks who claim to know how dangerous it is
out there in the "spike" jungle. There are folks who would have
you sprinkle little spike catchers all over the airplane and
there are those who still worship at the altar of avionics
master switches an cringe at the thought of hitting the system
with starter currents. I've taken more starting event traces
off the bus of cars, light planes and biz jets than I can count
and I've yet to catch one of the evil critters in the wild.
And to date, no one has answered my challenge to produce
a trace from a repeatable experiment that demonstrates their
existence. It's always been, "My brother-in-law's cousin has
a next door neighbor who knows a guy at the airport who melted
his whole stack of avionics to the ground 'cause he . . .
(1) left the avionics master on
(2) didn't install certain kinds of "protection"
(3) etc.
(4) etc.
Until such data comes forward, I have to advise that I have 40 years
experience, analysis and data that argues against the majority of the
dogma being preached with respect to transients and bus quality
and ZERO supporting data from anyone to the contrary.
Bob . . .
Message 5
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--> AeroElectric-List message posted by: Hal Kempthorne <hal_kempthorne@sbcglobal.net>
My old British Skymap non-color has developed some blank lines making it nearly
unusable. King now services these but not in an economically sane way. They
suggested contacting the Brits. I sent them email but no response. I suspect
they too want no part of it. My fear is that if I fix it, a different part
will fail.
Do any of you have any ideas of what to do with this once fabulous device? I mean,
besides chuck it in the dumpster or sell it 'as is' on ebay?
hal
Message 6
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| Subject: | Odyssey battery hold-down in an RV-8 |
--> AeroElectric-List message posted by: "czechsix@juno.com" <czechsix@juno.com>
Guys,
I just got my Odyssey PC680 battery and am trying to figure out how to strap it
down to the battery tray on the firewall of my -8A. Vans plans show to use a
U-shaped extrusion across the top of the battery with two long bolts that go
through each end of the extrusion and down through the sides of the battery tray.
Looks like it would work fine for a bigger Concorde battery but the tall/skinny
PC680 is a different story. I can sorta fit the extruded bar across the
aft part of the battery with enough clearance to stay away from the terminals,
but I'm wondering if I also need to secure the battery in some way to keep
it from tipping or sliding forward.
What have others done? Any pics out there?
Thanks,
--Mark Navratil
Cedar Rapids, Iowa
RV-8A N2D wiring almost done...!
Message 7
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| Subject: | Re: Solid State Relays vs. Solenoids |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 09:55 PM 5/23/2005 -0700, you wrote:
>--> AeroElectric-List message posted by: chad-c_sip@stanfordalumni.org
>
>Can anyone give me pros and cons of using solid state relays instead of
>solenoids for driving large current loads (lights, A/C compressor/hydraulic
>pump, etc.). I've used Crydom SCRs in the past for switching AC systems. I'm
>wondering if I couldn't use something like this:
>http://www.crydom.com/userResources/productFamilies/40/crydom_d06d.pdf to
>trigger my high-current loads.
>
>I'll still get transient spikes from switching inductive loads on the
>downstream side of the relay. But I shouldn't get the spikes on the bus-feed
>side of the relay as I would with a solenoid. Is that correct?
Conventional contactors do not propagate spikes to the supply
side that are any more noteworthy than a pure manual switch.
See my earlier post on Cessna service bulletin. We use solid
state contactors in our most demanding situations. Here's a relay
I helped develop for the tail de-ice system in a Beechjet.
http://www.aeroelectric.com/Pictures/Solid_State_100A_Contactor.jpg
Here's the same relay getting a "extreme environment" proof
test . . .
http://www.aeroelectric.com/Pictures/Solid_State_Endurance.jpg
This critter is good for 100A continuous and self-protects at
525A after about 100 mS.
>I'd appreciate
>any input. I've got to make a decision about how I want to wire these loads up
>in the next day or three.
The Crydom products are not leading edge but they are the
wave of the future for switching high currents in silicon
at DC. In the past 5 years, we've seen 60V Power MOS transistors
drop below 5 milliohms on-resistance. The 100A device illstrated
above has less than one milliohm on-resistance . . . it drops
less than 100 mV at 100A load for an internal dissipation of
less than 10 watts.
They're only going to get better from here.
As to spike suppression on the load side . . . whatever there
is to deal with is easily controlled with transorbs or the like.
The 100A relay is protected from 600V open circuit transients
with source impedance of 5 ohms (120A short circuit). This is
the design goal for induced lightning transients. The Crydom
product doesn't speak to such stresses and we wouldn't expect
it to. If your design goal is to go solid state for contactors,
your risk is low . . . IF you know and account for all the
variables in the application you propose.
Bob . . .
Message 8
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| Subject: | Re: Engraved overlay and S700-2-10 terminals |
--> AeroElectric-List message posted by: rv-9a-online <rv-9a-online@telus.net>
I have used Superior Panel Technologies (from Aircraft Spruce) custom
back-lit labels. They show up well during the day and at night. I
wrecked one and had to reorder... they doubled the price! Anyway, for
about $50 you can get a 14" label strip. You'll need a light source in
addition to this that can drive two or three label strips.
Although I don't like fiber optic lights in general (the fibers are
fragile and can be attacked by chemicals like lock-tite), the results
were great.
Vern Little
Ken wrote:
>--> AeroElectric-List message posted by: Ken <klehman@albedo.net>
>
>I am quite happy with white letters on clear TZ tape from a brother
>P-touch. The panel is painted medium gray. Once applied and pressed
>down, it is difficult to remove them without pulling the paint away too.
>I used half inch tape which on a 1180 model (about $40. on sale) which
>allows two lines of text if desired. Unlike lettraset the labels can
>easily be applied after the panel is installed and populated.
>Ken
>
>RURUNY@aol.com wrote:
>
>
>
>>--> AeroElectric-List message posted by: RURUNY@aol.com
>>
>>I'm drilling holes for the switches at this time and noticed that the
>>S700-2-10 switch from B&C I'm using for the Master (OFF/BATT/ALT) has the upper
>>left terminal marked 1 looking from the rear with the keyway up. Z-16 shows
>>number 1 at the bottom left terminal in the same orientation. Should I use the
no
>>1 on the switch?
>>
>>The post below shows a post from Bob in Jan in response to a switch keyway
>>question.
>>My question here is where are engraved overlays for switch labeling
>>available, are they custom or do it yourself kits?
>>My plan for labeling after panel drilling is complete is to paint it with
>>dark grey rustoleum,
>>use rub on transfer letters and numbers from Tower Hobbies, then use
>>rustoleum flat clear
>>over panel. Any better sugestions within a reasonable budget other than
>>stickers from a label
>>maker?
>>
>>Thanks
>>Brian
>>
>>
>
>
>
>
Message 9
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"Darwin N. Barrie" <ktlkrn@cox.net>
| Subject: | Panel vs Firewall Ground--do the electrons care? |
--> AeroElectric-List message posted by: "Roger Evenson" <revenson@comcast.net>
Just read Bob's new chapter on Audio Systems. Given that a single-point ground
system is best to eliminate noise from ground loops, I don't understand the rationale
for a separate audio ground near the radio stack. Why is it considered
poor practice to run both audio and all other aircraft equipment grounds to
a single firewall ground block?
Further, what's the difference between a single firewall ground for everything
and a panel ground with a wire connecting the panel ground to the firewall ground?
Does it matter to the audio system?
Roger Evenson, Toasty in Tucson.
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