Today's Message Index:
----------------------
1. 06:14 AM - Re: Open source product development for OBAM aircraft (Eric M. Jones)
2. 07:29 AM - Re: OS Wig-Wag Project (gregmchugh)
3. 07:46 AM - Re: OS Wig-Wag Project (Robert L. Nuckolls, III)
4. 08:31 AM - Re: OS Wig-Wag Project (Daniel Hooper)
5. 09:11 AM - Re: OS Wig-Wag Project (Robert L. Nuckolls, III)
6. 09:14 AM - Re: Re: OS Wig-Wag Project (Robert L. Nuckolls, III)
7. 08:16 PM - Antenna mounting-doubler (Rick Lark)
8. 09:13 PM - Secrets Techniques (John Loram)
9. 09:28 PM - Re: Antenna mounting-doubler (Robert L. Nuckolls, III)
10. 09:37 PM - Re: Secrets Techniques (Mike Nellis)
11. 11:19 PM - Re: Secrets Techniques (John Loram)
Message 1
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Subject: | Re: Open source product development for OBAM aircraft |
> Eric: Express PCB is also very good. The only disadvantage is that it is linked
to the particular board supplier - which is fine as long as that is who you
want to deal with. With Eagle you can use
> the Gerber files it generates with any board supplier.
Dick, ExpressPCB is full of surprises. They will send you the Gerber Files for
a small fee after the first run, I believe. (Check with them for the most recent
policy). Their mini-board service also expands to almost anything else you
want, other sizes, two or four layers, other quantities, for competitive prices.
They also don't quibble about the number of boards you put on one sheet, although
they have a limit of 350 holes per sheet on their standard 3-PCB mini-board
service (...and I bump up against the hole-limit all the time!).
ps: Don't confuse the original "Express PCB" with the copycat "PCB Express".
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371262#371262
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Subject: | Re: OS Wig-Wag Project |
Bob,
Looks good for what I would need for a wig-wag...
Here are some possible typos I think I picked up...
On page 2 the processor part number is listed wrong.
On page 3 at the top right I think that it should read P-1, not P-11.
On page 3 Pin 6 of the micro is being used as GP1 in this application.
On page 3 Pin 7 of the micro is being used as GP0 in this application.
and a couple of questions...
1. Pin 12 on the d-sub connector seems to be unused but also shown
differently than the other pins on the page 1 drawings. Is this
a convention of some sort?
2. Looking at the PIC12F683 data sheet there are some confusing
instructions on using MCLR with Power on Reset but I think that
Pin 4 could be left unconnected for this application or
used for another purpose since there is no external reset circuit.
What is your reading on this?
3. Not sure how much real estate is left on the board but with Pin
4 freed up and Pin 3 unused you might be able to add the Under Voltage
module functions into this module. Connect one pin as an A/D to
read the bus voltage and use the other pin to drive the warning
LED using a spare d-sub pin. Maybe also figure out how to handle
the relay control for the aux battery. Maybe this is something for
the next spin of the board...
As it is, it meets my needs for a wig-wag module but I can see a software
option that might be useful for users with other configurations of lights.
In my case I have two landing lights on the wing and really only need
to have them both off, both on, or the wig-wag. If other users have
a Taxi light and a Landing light they may want to be able to have
an alternate control function that allows: All Off, Taxi On, All On, &
Wig-Wag (or some variation of four different states). Changing the
function of the switch as shown to handle Off, Taxi, All On and then
adding a second switch to ground both inputs for Wig-Wag would
allow this to be done with only a software change needed to implement
in the module. An option for those who would want it...
It may be little early to be looking at Version 2 of the module but I will
throw out a couple of items that might be useful to consider that require
more than a minor spin on the board.
1. Allow for drop in of a PICAxe 8 pin module. This would require
realigning Pin 2 and Pin 7 to handle the Serial In and Out for the PICAxe
configuration and moving the current functions to other pins. Two resistors
are the only added components for the PICAxe serial I/O circuit. Pin 7
can be reconfigured as a regular I/O pin in the application or left
to handle Serial Out (maybe to a remote display?). With Pin 2 and
Pin 7 brought out to the d-sub you would have the capability to
connect to the PICAxe tools and do serial communication with the chip
in the application via the d-sub.
2. In-Circuit Programming of the PIC is something that might be useful
when using the standard PIC chip. Not sure about the need for it...
3. As I noted above, an easy add-on for the current module would
appear to be the functions handled by the Under Voltage module
(warning light and aux battery control).
I expect that others have already come up with more ideas for
using the module. With digital I/O, analog inputs, and a serial
interface there a lots of possible functions for the module even with
only an 8 pin micro.
Lots of options, which is good...
I will be continuing work on a software version to handle the
basic wig-wag function in the next few days. Should have
an initial version available within a week or so.
Greg McHugh
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=371274#371274
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Subject: | Re: OS Wig-Wag Project |
>I'll take another pass at the 'sieve' tomorrow
>and maybe get some boards on order. I have all
>the parts.
Some background on the decisions that went
into satisfaction of design goals:
I started with the following ideas for
crafting the configuration I published:
1. Use the already developed package based
on Polycase enclosure and D15 connector. I
have cases and lids already cut to accept the
connector. Of course, this sets the boundaries
on the ECB.
2. Use simple on-off-on toggle switch to achieve
OFF-WW-ON control functionality. Easily handled
with software logic.
3. Minimum parts count.
4. Minimum variety of parts.
5. Maximize heat-sink copper for the FETs
6. Add some functional indictors for
as-development tools (a couple of LEDs)
so that bench testing of software needs only
a switch and power supply.
----------------
Parts selection was pretty easy. As one
can see from the schematic, all resistors
and capacitors are the same value. This
makes it easier to order, stock, and
install with minimized error. The only
parts that required any "calculation for
performance" was the voltage divider for
the power supply (exact value not critical
and they only needed to be equal). And
the series resistor for the shunt regulator.
The calculated optimum value could be achieved
by paralleling 4 of the common bill of materials
value. 4.99K / 4 gives us about 1200 ohms
at better than 1 watt because the heat doesn't
come out of a single device . . . but is spread
over larger area.
The other values go to transient immunity.
Two standard practice bypass capacitors on supply
rails, two capacitors and two transorbs
protecting fragile silicon from stuff conducted in
on the ship's wiring.
This is a good example of what my cohorts
at HBC called a "cotton ball" . . . very
non-critical components (tells us that
drifts in performance due to component
tolerance/drift are insignificant). The
thought processes that go toward component
selection are pretty ho-hum.
Not to take away from the ultimate
functionality of the assembly. Once the
silicon is safely wrapped in environmental
cotton, the magic poured into the source
code is relatively unrestricted.
A similar philosophy was adopted for the
'do-lots' board from which this project
evolved. Figure out a way to wrap an 8-pin
PIC up in a deep sea diving suit and then
teach it how to sing, dance and do dishes.
I'll order boards today. As Eric mentioned,
ExpressPCB doesn't fuss about what is on a
miniboard (3 pieces returned in 3 days for
$70). Each mini-board will give us two
finished boards with a couple of avionics
ground bus boards thrown in on the side . . .
sorta like this:
Emacs!
So we'll end up with 6 boards for the development
work at a cost of just over $11 each and turned
around in 3 days. If I sell some avionics grounds
with the 'residuals' then the out-of-pocket development
costs go down.
Folks interested in doing software for this
project need to chime up. I'll provide an
assembled board with a control switch attached.
You'll need a 12v source (2 el-cheapo WalMart
lantern batteries?) and a development system
of your choice. I'll throw in a couple of
PIC chips and install a socket on the board
for ease of swapping the chip between programmer
and the end product demonstration.
It's my vision for this project to publish all
the drawings, ECB source files, and software
sources which anyone can use to carry this
project (or perhaps another functionality on
the same hardware) forward. Of course, most
individuals accessing this data have no interest
in evolving/building their own. But this could
lay the ground work for others to cultivate
their own ideas for other products in a garden
we've already planted with expertise contributed
from a family of participants.
That's what Open Source is all about . . .
Bob . . .
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Subject: | Re: OS Wig-Wag Project |
In that case, maybe consider dropping a Open Source Hardware logo in the cop
per...
http://freedomdefined.org/OSHW
http://oshwlogo.com/
>
> It's my vision for this project to publish all
> the drawings, ECB source files, and software
> sources which anyone can use to carry this
> project (or perhaps another functionality on
> the same hardware) forward. Of course, most
> individuals accessing this data have no interest
> in evolving/building their own. But this could
> lay the ground work for others to cultivate
> their own ideas for other products in a garden
> we've already planted with expertise contributed
> from a family of participants.
>
> That's what Open Source is all about . . .
>
> Bob . . .
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Subject: | Re: OS Wig-Wag Project |
At 10:25 AM 4/19/2012, you wrote:
>In that case, maybe consider dropping a Open Source Hardware logo in
>the copper...
>
><http://freedomdefined.org/OSHW>http://freedomdefined.org/OSHW
>
>http://oshwlogo.com/
Interesting! Hadn't seen that before. I'm
not ExpressPCB has a feature that would
allow us to craft that exact symbology
onto the board . . . but certainly documents
that accompany the package could included
it. I'll see what I can do.
Bob . . .
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Subject: | Re: OS Wig-Wag Project |
At 09:28 AM 4/19/2012, you wrote:
Good input. Give me a day or so to get the disagreements
sifted and consider the broader options.
Bob . . .
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Subject: | Antenna mounting-doubler |
Hi Bob,
I'm aware that a doubler plate/skin connection for mounting a nav or com
antenna requires a nice shiny surface. But, will alodining the
surfaces make any difference with antenna performance?
Thx, Rick
Vans #40956
Southampton, Ont
Message 8
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Subject: | Secrets Techniques |
Sixty years I've been doing this! Built all my own ham radio gear as a
teenager in the 50's, got a EE degree from a prestigious university, spent
my adult life as a development engineer designing medical and laboratory
instruments. You'd think I could strip a multiconductor shield Tefzel
insulated cable in my sleep, but it's a bit@h! I make a mess of the shield
when I try to remove the Tefzel. What is the secret trick to it!
thanks all, -john-
Message 9
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Subject: | Re: Antenna mounting-doubler |
At 10:13 PM 4/19/2012, you wrote:
>Hi Bob,
>
>I'm aware that a doubler plate/skin connection for mounting a nav or
>com antenna requires a nice shiny surface. But, will alodining the
>surfaces make any difference with antenna performance?
I presume you're talking about a commercial comm
wisker that mounts with 3 or 4 screws and has
a BNC connector centrally located in the hole
pattern.
See:
http://tinyurl.com/6rwodso
Practical electrical connection is made with
the airframe only at the areas where there are
large clamp up forces around the screws. These
forces go to essentially zero at more than 1/4"
away from the mounting hardware. The goal is to
things clean if not bright around each
of the mounting screws on all mating surfaces.
The end product will be the best we know how
to do . . . short of welding the antenna base
to the skin. The goal is 'gas tightness' within
the cleaned areas . . . so screw the nuts down
good and tight. Metal lock-nuts would be good.
Bob . . .
Message 10
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Subject: | Re: Secrets Techniques |
You've been doing it so long, you've probably wore the tool out or at
the very least, dulled it.
Mike
> Sixty years I've been doing this! Built all my own ham radio gear as a
> teenager in the 50's, got a EE degree from a prestigious university,
> spent my adult life as a development engineer designing medical and
> laboratory instruments. You'd think I could strip a multiconductor
> shield Tefzel insulated cable in my sleep, but it's a bit@h
> <mailto:bit@h>! I make a mess of the shield when I try to remove the
> Tefzel. What is the secret trick to it!
> thanks all, -john-
> *
>
>
> *
Message 11
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Subject: | Secrets Techniques |
Tool! A special tool!? I love tools! What tool!
-john-
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Mike
Nellis
Sent: Thursday, April 19, 2012 9:36 PM
Subject: Re: AeroElectric-List: Secrets Techniques
You've been doing it so long, you've probably wore the tool out or at the
very least, dulled it.
Mike
Sixty years I've been doing this! Built all my own ham radio gear as a
teenager in the 50's, got a EE degree from a prestigious university, spent
my adult life as a development engineer designing medical and laboratory
instruments. You'd think I could strip a multiconductor shield Tefzel
insulated cable in my sleep, but it's a bit@h! I make a mess of the shield
when I try to remove the Tefzel. What is the secret trick to it!
thanks all, -john-
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