Today's Message Index:
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1. 07:38 AM - D-Sub carrying current (rparigoris)
2. 08:21 AM - Re: Re: Dark and stormy night during CAVU (Robert L. Nuckolls, III)
3. 08:33 AM - Re: Re: Switch Question (Robert L. Nuckolls, III)
4. 08:43 AM - Re: D-Sub carrying current (Robert L. Nuckolls, III)
5. 09:25 AM - Re: D-Sub carrying current (rparigoris)
6. 10:27 AM - Re: D-Sub carrying current (rparigoris)
7. 09:19 PM - Re: Z101B Questions (Patrick Nelson)
Message 1
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| Subject: | D-Sub carrying current |
Hi Group Two D-Sub questions: 1) Is it OK to use only 1 D-Sub machined and gold
plated pin to carry current to my 5 amp circuit breaker used to control overvoltage
on my B&C LRD regulator (crowbar)? 2) I have another circuit that will
carry up to 8 amps. I want to split the load between two D-Sub pins. I remember
reading about using a resistor on both pins so the difference in resistance
of the two pins would be much closer. Question) what value resistor and how many
watt capacity? Thx. Ron P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499546#499546
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| Subject: | Re: Dark and stormy night during CAVU |
>
>I can imagine at least one RR design that would shunt the AC coils
>out when reaching the setpoint, which would nullify the tach signal.
For that situation, I suspect the PM alternator
output currents never go to zero. One could get
a righteous representation of AC current frequency
by passing one lead of the alternator coil through
a hall sensor. AMPLOC has a line of candidates
for this task.
https://tinyurl.com/yxfeta3h
> The design of the Revmaster (series regulator, in my personal
> venacular) does not shunt the PMA coils but instead, opens the PM
> circuit when the battery voltage reaches a set value (with an SCR
> that completes the PMA circuit to battery common). If the tach is
> wired on the AC side of the RR, (as Revmaster shows it) the voltage
> signal will still drive the tachometer when the RR reaches setpoint
> and opens the circuit to the battery (as described by Bob, with
> plenty of extra power to spare).
agreed
>Alternatively, if the tach is on the DC side of the RR, the signal
>is likely to die out, as the RR intermitantly disconnects the PMA
>from the battery,
Validity of the alternator's AC information
is not preserved across the RR. Valid tach data
will be available only at the AC output leads
from the alternator.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 3
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| Subject: | Re: Switch Question |
>
>Totally agree, it's just a matter of finding someone at the local
>FSDO that has the same point of view. John
Are there any Type Clubs for your airplane?
It might be possible to got a copy of an
already approved 337 for doing this job.
Using that as foundation for your new
endeavor will go a long way toward assuaging
timidity on the part of individuals with
little or no familiarity with vintage aircraft.
Use the battery contactor installation on any later
version of that aircraft to create a narrative/
photo essay on a proposed modification to your
airplane.
Lacking that, find an STC for ANY such modification
to a vintage aircraft. Use it as a pattern to
create your own documentation.
Don't ASK 'em how to do it, TELL them how you're
going to do it on a foundation of prior
art.
When and if you're successful, preserve copies
of your approved paperwork and share with interested
owners. You can become a repository for a
knowledge-nugget of tribal knowledge.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 4
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| Subject: | Re: D-Sub carrying current |
At 09:33 AM 11/27/2020, you wrote:
>
>Hi Group Two D-Sub questions: 1) Is it OK to use only 1 D-Sub
>machined and gold plated pin to carry current to my 5 amp circuit
>breaker used to control overvoltage on my B&C LRD regulator (crowbar)?
Yes
> 2) I have another circuit that will carry up to 8 amps. I want to
> split the load between two D-Sub pins. I remember reading about
> using a resistor on both pins so the difference in resistance of
> the two pins would be much closer. Question) what value resistor
> and how many watt capacity? Thx. Ron P.
http://www.aeroelectric.com/Pictures/Schematics/Paralleled_DSub_Pins.pdf
This is a paralleling technique proposed and
approved on the GQM163 SSST target and
later adopted in power distribution components
of the B4000 bizjet.
There are variations on this theme which demand a
few more details on your proposed application.
What are the connections to pins on both
sides of the interface? Are we talking about
a 8A continuous load?
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 5
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| Subject: | Re: D-Sub carrying current |
Hi Bob Thx. for reply. 8 amp continuous load perhaps 10 minutes per flight which
is for cooling fans FWF about 30" forward of connector, aft of connector is
a switch about 10" away but could easily use 12" of #22 wire. If a resistor were
to be used for two wires and 4 amps each, would it need to be rated for 58
watts? I like your 12" of #22 wire solution! Ron P.
Read this topic online here:
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| Subject: | Re: D-Sub carrying current |
Hi Bob Forget second half of my question, I see you had written mOhms, not ohms.
I missed the m. Ron P.
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| Subject: | Re: Z101B Questions |
Thank you for the replies!
> How would you use those numbers if you had them?
It terms of battery current, that's what I'm used to seeing in other planes and
it can be used to detect an alternator failure. However, I see your point of
using the voltmeter to detect an alternator failure instead and alternator current
gives a more useful indication of total electrical load.
>
> No fix necessary. Diodes just don't do that any
> more and then it would require more than one to
> cause a drain which would be mitigated by the b-lead
> fuse.
>
I looked more at the BC410-H alternator I'm planning to use for the aux alternator
and I think you're right that it won't be a problem. There should be no internal
connection between the B and F terminals, in theory.
I saw an example in a car where an alternator diode being shorted caused the charging
system light on the dashboard to stay lit - even with the car completely
shut off.
>
> They share a switch but are not 'tied' together. The switch
> serves the same function as battery master . . . 3 position
> switch that closes the relay first and alternator next.
>
Please excuse my still learning electrical systems, but this doesn't make sense
to me. The aux alternator provides power to the battery side of the main contactor.
There's not a second battery and "aux master" like you'd have with a
Z-14 setup. One function of this switch is to turn on the aux alternator.
The other feature of this switch is to provide an alternate power source to the
brownout bus. This could be used as a "clearance delivery" feature or like the
"E-bus Alternate Feed" as exists on some of the other schematics (like Z-10).
I'm still not understanding why these share a switch.
Why would you want the aux alternator field powered to use the "clearance delivery"
function?
> 5. Yes, timing.
Thank you both for answering the question about the power source for the brownout
booster. That completely makes sense and I'm glad I asked :-)
Thanks again for the info!
-Patrick
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