Today's Message Index:
----------------------
1. 05:52 AM - Power buss feed connection (LarryRobertHelming)
2. 05:59 AM - Re: MAC trim gauge & switch connection (Robert Dickson)
3. 07:44 AM - Re: Power buss feed connection (Paul Wilson)
4. 12:11 PM - Mid-Continent turn coordinator -- tilt (Fergus Kyle)
5. 03:31 PM - Re: ground plane (Gilles.Thesee)
6. 03:43 PM - Another shielding question (HCRV6@aol.com)
7. 05:06 PM - Ratchet Crimper (Byron & Jean)
8. 05:27 PM - ground plane for comm. (peter goudinoff)
9. 05:37 PM - Re: Ratchet Crimper (Robert L. Nuckolls, III)
10. 05:37 PM - Re: ground plane (Robert L. Nuckolls, III)
11. 08:33 PM - V=IR problem (richard@riley.net)
12. 08:50 PM - Re: V=IR problem (BobsV35B@aol.com)
13. 08:54 PM - Re: V=IR problem (Robert L. Nuckolls, III)
14. 09:04 PM - Re: V=IR problem (Shannon Knoepflein)
15. 09:16 PM - Re: V=IR problem (richard@riley.net)
16. 09:21 PM - Re: V=IR problem (John Rourke)
17. 09:26 PM - Re: V=IR problem (BobsV35B@aol.com)
18. 09:48 PM - Re: V=IR problem (John Rourke)
19. 09:51 PM - Re: V=IR problem (John Rourke)
20. 11:41 PM - Re: Power buss feed connection (James Foerster)
Message 1
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| Subject: | Power buss feed connection |
--> AeroElectric-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
RE: Power buss feed connection
Bob or anyone, what is the preferred method for connecting the primary +
feed to the main buss or other power buss? As I see it, one could connect
it to one of the PIDG and put a large rated fuse in it or is it better to
connect it to the metal screw post at the end of the buss? What other use
could the metal screw post be used for?
Larry in Indiana, RV7 Tip-up O-360 3XG reserved.
Starting to work with Bob's power busses
Message 2
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| Subject: | Re: MAC trim gauge & switch connection |
--> AeroElectric-List message posted by: Robert Dickson <robert@thenews-journal.com>
> Suggest you consider hooking the DIM COMMAND line to
> some other night lighting circuit like nav lights.
> Any time the nav lights are on, the indicator
> intensity goes to dim.
>
> Bob . . .
great explanation, Bob. I wouldn't have understood the trim indicator
schematic without your help, and I sure wouldn't have thought of the
solution.
thanks,
Robert Dickson
RV-6A electrical
do not archive
Message 3
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| Subject: | Re: Power buss feed connection |
--> AeroElectric-List message posted by: Paul Wilson <pwilson@climber.org>
Or one could get the male faston adapter meant to be used for the battery bolt.
It has three tabs and one big slot for a big battery bolt. For use with smaller
bolts we use on the airplane one could solder the correct ring terminal to
get rid of the slot. I think I got them at either Radio Shack or at an Auto supply
place.
Paul
========
At 7:52 AM -0400 6/5/03, LarryRobertHelming wrote:
>--> AeroElectric-List message posted by: "LarryRobertHelming" <lhelming@sigecom.net>
>
>RE: Power buss feed connection
>
>Bob or anyone, what is the preferred method for connecting the primary +
>feed to the main buss or other power buss? As I see it, one could connect
>it to one of the PIDG and put a large rated fuse in it or is it better to
>connect it to the metal screw post at the end of the buss? What other use
>could the metal screw post be used for?
>
>Larry in Indiana, RV7 Tip-up O-360 3XG reserved.
>Starting to work with Bob's power busses
--
Message 4
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| Subject: | Mid-Continent turn coordinator -- tilt |
--> AeroElectric-List message posted by: "Fergus Kyle" <VE3LVO@rac.ca>
Cheers,
Just so's it doesn't appear that Ol' Bob is alone in the Turn
and Bank persuasion, I heartily agree with his stand and will have but a T&B
in my Europa for coordinated footwork (and perhaps the odd clumsy stumble
out of cloud).
Ferg
Message 5
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| Subject: | Re: ground plane |
--> AeroElectric-List message posted by: "Gilles.Thesee" <Gilles.Thesee@ac-grenoble.fr>
> The "optimum" tuned ground plane is same radius as height of
> antenna . . . or about 5.2" diameter for transponder. But
> it will probably work just fine on the access plate too.
>
> Bob . . .
Bob,
I'm afraid my transponder ground plane is 5.5" diameter. Will that make a
big difference ? Shall I have to make a new one ?
Thanks,
Gilles
Message 6
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| Subject: | Another shielding question |
--> AeroElectric-List message posted by: HCRV6@aol.com
Bob:
Hoping for your expert opinion. I am using a SoftCom ATC-2P intercom with a
KX-125 Navcom. The factory prewired harness for the intercom has only
unshielded wires. I have installed it as received but I have routed the mic and
phone jack wiring so as to keep them at least 2 inches away from other wires
except for a span of about 3 inches where all the wiring passes through one panel.
Now I am installing the KX-125, for which I have to fabricate the harness,
and the wiring diagram calls for shielding on the connections to the intercom.
This would require disassembly and rewiring of the installed intercom harness,
a tough job because I potted the backside of the connector.
My question is, if I continue to keep the audio and mic key wires separate
from other wires, is it reasonable to expect that I can forego shielding on
these lines, or should I "bite the bullet" and rework the intercom harness now?
BTW, I am using your single point "forest of tabs" for all grounds, including
avionics.
Harry Crosby
Pleasanton, California
RV-6, firewall forward and finishing electrical
Message 7
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--> AeroElectric-List message posted by: "Byron & Jean" <byronjean@ticon.net>
Bob & List:
I'm looking for a quality ratchet crimper and lugs for #2 & #4 welding cable. I'm
trying not to buy the real expensive ones, unless I have too. Any recommendations
would be appreciated.
Thanks
Byron
Message 8
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| Subject: | ground plane for comm. |
--> AeroElectric-List message posted by: peter goudinoff <peterg@dakotacom.net>
Lancair Legacy still early in construction; only thing done in cockpit
so far (besides loadpads) is seat reinforcement and canopy latch. q:
should I install the comm. ant. groundplane (there's already a slot for
it on the belly) now or wait 'til later?
peter goudinoff
L2K #200
Message 9
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| Subject: | Re: Ratchet Crimper |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:04 PM 6/5/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Byron & Jean" <byronjean@ticon.net>
>
>Bob & List:
>I'm looking for a quality ratchet crimper and lugs for #2 & #4 welding
>cable. I'm trying not to buy the real expensive ones, unless I have too.
>Any recommendations would be appreciated.
>Thanks
>Byron
I solder this size terminal. There are so few terminals to put
on and good tools are expensive. There's an article on how
to solder the big wires on my website at:
http://www.aeroelectric.com/articles/big_term.pdf
I own about a dozen crimp tools but nothing bigger
than the 10-12AWG PIDG terminal.
Bob . . .
Message 10
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| Subject: | Re: ground plane |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 12:30 AM 6/6/2003 +0200, you wrote:
>--> AeroElectric-List message posted by: "Gilles.Thesee"
><Gilles.Thesee@ac-grenoble.fr>
>
>
> > The "optimum" tuned ground plane is same radius as height of
> > antenna . . . or about 5.2" diameter for transponder. But
> > it will probably work just fine on the access plate too.
> >
> > Bob . . .
>
>
>Bob,
>
>I'm afraid my transponder ground plane is 5.5" diameter. Will that make a
>big difference ? Shall I have to make a new one ?
Nope . . . keep on truck'n
Bob . . .
Message 11
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--> AeroElectric-List message posted by: richard@riley.net
I have an 8 day clock that wants 5V for the internal light. I have a 12v
airplane.
I know if measure the clock's resistance with an ohm meter I can figure out
how big a resistor to put in line with it. Can someone walk me through the
equation?
Message 12
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 6/5/03 10:34:01 PM Central Daylight Time,
richard@riley.net writes:
> I know if measure the clock's resistance with an ohm meter I can figure out
>
> how big a resistor to put in line with it. Can someone walk me through the
> equation?
>
Just curious, why not use a ZENER?
Happy Skies,
Old Bob
Message 13
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 08:32 PM 6/5/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: richard@riley.net
>
>I have an 8 day clock that wants 5V for the internal light. I have a 12v
>airplane.
>
>I know if measure the clock's resistance with an ohm meter I can figure out
>how big a resistor to put in line with it. Can someone walk me through the
>equation?
Light bulbs have a very steep positive temperature
coefficient of resistance. The resistance reading
you'll get with an ohmmeter will be much lower
than actual operating resistance.
You need to attach the clock to a 5v power supply
and measure the current with the lamp operating.
Then subtract 5v from 14v to get the resistor drop.
Your formula is R=E/I so divide the voltage drop
by measured current to yield appropriate size resistor.
Bob . . .
Message 14
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--> AeroElectric-List message posted by: "Shannon Knoepflein" <kycshann@kyol.net>
V=IR is the start
You want 5 volts across the clock, so measure its resistance. Now you
know Vclock and Rclock, so calculate Iclock from equation. Say Rclock
is 5ohms, the Iclock would be 1A.
Now we know the current through the circuit needs to be 1 Amp, and we
need to drop 12-5=7 volts across the other resistor. So, Vres is 7
volts, Iclock=Iresistor=1A, so again, using the equation we can find the
R value you need is 7ohms.
Size your resistor power by P=I
2 * R, so 1*1*7, or 7watts in the case.
Oversize it by a factor of about 2 I'd say to be safe.
Also, you might want to consider 14.4 volts in these calcs instead of
12, depending on how you set up your electrical system.
These are all hypothetical, but should help you get it figured out.
Basically, sum of all current in and out of a node is zero, and sum of
all voltages around a loop is also zero. Hopefully you can see these
laws at work in the above example.
Another way would be to just use a small 7805 5v voltage regulator that
takes 12 in and would put out enough 5V to run your clock.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
richard@riley.net
Subject: AeroElectric-List: V=IR problem
--> AeroElectric-List message posted by: richard@riley.net
I have an 8 day clock that wants 5V for the internal light. I have a
12v
airplane.
I know if measure the clock's resistance with an ohm meter I can figure
out
how big a resistor to put in line with it. Can someone walk me through
the
equation?
Message 15
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: richard@riley.net
At 11:49 PM 6/5/03 -0400, you wrote:
>Just curious, why not use a ZENER?
My understanding was that a Zener wouldn't let me dim the internal lighting
with the rest of the panel. If I'm wrong, please let me know.
If I string together 3 D cells, would that be close enough to 5 v to get an
accurate voltage drop?
Message 16
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: John Rourke <jrourke@allied-computer.com>
Actually, I've found it difficult to reliably measure the resistance
of a lamp directly with an ohmmeter - if it's LED, you won't get a
meaningful answer, and if it's incandescent, the cold resistance is
different from the hot (lighted) resistance. Also, if there's any
electronics in it at all (apparently not, by "8-day clock" I take it to
mean it's mechanical, only the light needs electrical), I would not
depend solely on a dropping resistor anyway, I'd want a 5.1v Zener in
there too.
But, given a mechanical clock, I'd simply first find the current it uses
at 5 volts (use a milliammeter and 4 NiCads or NiMHs), then divide that
into 9 (14-volt supply - 5-volt desired = 9-volt drop)... Example: let's
say you find it uses 50 milliamps (.05A) - you want to drop 9 volts so
that would be 9/.05 or 180 ohms. Wattage is I*I*R, or 1/20*1/20*180 in
this case... about 1/2 watt so make it a 1-watt resistor and make sure
it has a bit of room to breathe. Maybe it would just be better to swap
the 5-volt for a 12-volt lamp if possible?
-John R.
richard@riley.net wrote:
>--> AeroElectric-List message posted by: richard@riley.net
>
>I have an 8 day clock that wants 5V for the internal light. I have a 12v
>airplane.
>
>I know if measure the clock's resistance with an ohm meter I can figure out
>how big a resistor to put in line with it. Can someone walk me through the
>equation?
>
>
>
>
Message 17
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: BobsV35B@aol.com
In a message dated 6/5/03 11:17:19 PM Central Daylight Time,
richard@riley.net writes:
> My understanding was that a Zener wouldn't let me dim the internal lighting
>
> with the rest of the panel. If I'm wrong, please let me know.
>
Good Evening Richard,
I am definitely one of those electrically challenged types, but I have used
Zeners for dimming purposes. What is so nice about a Zener is that it drops
the voltage to the required voltage regardless of what the load is. I guess I
should say; as long as the load is within the capacity of the zener.
The first time I used one was to dim a set of four GPS annunciator lights.
Since they were sometimes all on at the same time and other times only one or
two were on, a resistor wouldn't work. The zener did the job perfectly. I
think it is all just magic!
Surely, some of the folks on this list will explain it much better than I
can.
Happy Skies,
Old Bob
Message 18
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: John Rourke <jrourke@allied-computer.com>
You're right about the zener cancelling out the dimming to a large
degree - as for 3 D-cells, it's close enough (4.5 volts) but 4 NiCads
are closer (NiCads start out near 1.4 volts, but quickly drop to 1.25
under about any load)
-John R.
richard@riley.net wrote:
>--> AeroElectric-List message posted by: richard@riley.net
>
>At 11:49 PM 6/5/03 -0400, you wrote:
>
>
>
>
>>Just curious, why not use a ZENER?
>>
>>
>
>My understanding was that a Zener wouldn't let me dim the internal lighting
>with the rest of the panel. If I'm wrong, please let me know.
>
>If I string together 3 D cells, would that be close enough to 5 v to get an
>accurate voltage drop?
>
>
>
>
Message 19
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| Subject: | Re: V=IR problem |
--> AeroElectric-List message posted by: John Rourke <jrourke@allied-computer.com>
Bob, that's indeed a great way to independently dim a set of lamps,
independent of load... but I think Richard has the opposite requirement
- a fixed load that he wants to dependently dim with the master dimmer.
A zener won't work for that.
-John R.
BobsV35B@aol.com wrote:
>--> AeroElectric-List message posted by: BobsV35B@aol.com
>
>In a message dated 6/5/03 11:17:19 PM Central Daylight Time,
>richard@riley.net writes:
>
>
>
>>My understanding was that a Zener wouldn't let me dim the internal lighting
>>
>>with the rest of the panel. If I'm wrong, please let me know.
>>
>>
>>
>
>Good Evening Richard,
>
>I am definitely one of those electrically challenged types, but I have used
>Zeners for dimming purposes. What is so nice about a Zener is that it drops
>the voltage to the required voltage regardless of what the load is. I guess I
>should say; as long as the load is within the capacity of the zener.
>
>The first time I used one was to dim a set of four GPS annunciator lights.
>Since they were sometimes all on at the same time and other times only one or
>two were on, a resistor wouldn't work. The zener did the job perfectly. I
>think it is all just magic!
>
>Surely, some of the folks on this list will explain it much better than I
>can.
>
>Happy Skies,
>
>Old Bob
>
>
>
>
Message 20
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| Subject: | Re: Power buss feed connection |
--> AeroElectric-List message posted by: "James Foerster" <jmfpublic@attbi.com>
Larry,
Use the post with a ring terminal and a locking nut or lock washer. That is what
that post is for. It would be useless to put the current for the whole fuse
block through a big fuse: the fuse protects nothing. Also, the PIDG connectors
may be useful to 20 amps, but your fuse block could draw more. The ring terminal
is the appropriate connection here. If you wish to protect the feed wire
from the contactor to your fuse block, you could use a fusable link if it
exceeds the 6 inch rule. Bob Nucholls does not worry much about exceeding the
6 inch rule according to a recent post, so a longer wire to the contactor with
attention paid to avoid chaffing the insulation should be OK.
Jim Foerster J400, 50%
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