Today's Message Index:
----------------------
1. 08:57 AM - Re: Voltage Regulator Problem (frank3)
2. 09:13 AM - Re: Re: Permanent Magnet Alternators - Over Voltage Protection (rayj)
3. 09:13 AM - Re: Re: Voltage Regulator Problem (Robert L. Nuckolls, III)
4. 10:16 AM - Re: Re: Permanent Magnet Alternators - Over Voltage Protection (Andrew Zachar)
5. 10:34 AM - DIY Over Voltage Protection (Robert L. Nuckolls, III)
6. 11:05 AM - Re: Re: Honeywell Rocker lamp wiring (Bill Watson)
7. 11:20 AM - Video Inspection Tool (Eric M. Jones)
8. 11:41 AM - Re: Permanent Magnet Alternators - Over Voltage Protection (user9253)
9. 12:44 PM - Re: Re: Permanent Magnet Alternators - Over Voltage Protection (Peter Mather)
10. 12:56 PM - Re: Voltage Regulator Problem (frank3)
11. 02:03 PM - DIY Over Voltage Protection (Robert L. Nuckolls, III)
12. 02:27 PM - Re: Video Inspection Tool (David)
13. 02:54 PM - Re: Re: Voltage Regulator Problem (Robert L. Nuckolls, III)
14. 03:32 PM - Re: Video Inspection Tool (Eric M. Jones)
15. 11:18 PM - DIY CBOVM: variations on a theme (Robert L. Nuckolls, III)
Message 1
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Subject: | Re: Voltage Regulator Problem |
Bob
Thanks for clarifying.
With relay circumvented (fat wires disconnected from relay but joined together),
B+ = 11.6v steady; EIS steady 10.8v. No change to either reading with RPM increase.
Re the "little wires", neither had voltage with master on ALT.
Reconnected relay and retested, B+ = 1.9v at start and slowly increased to 4v after
10 min engine run. Same reading immediately after engine off. EIS showed
10.8v. No change to either reading with RPM increase.
Further suggestions/assessment?
--------
Frank
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331739#331739
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Subject: | Re: Permanent Magnet Alternators - Over Voltage |
Protection
do not archive
THIS email is why I love this list. I didn't understand a word of it!!!! :)
But if I keep reading this list and studying one day I will.
Thanks again, Bob.
Raymond Julian
Kettle River, MN
On 02/20/2011 11:13 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 07:31 PM 2/20/2011, you wrote:
>> <fran4sew@banyanol.com>
>>
>> I read about the Silicon Bilateral Switch on the internet today.
>> Evidently it is not necessary to connect the gate because the SBS will
>> start conducting when the voltage reaches a certain value without the
>> gate connected.
>> I am still wondering if a zener diode could be used instead of the
>> SBS. If not, it would be interesting to know what the disadvantages of
>> the zener diode are, or if it would even work at all.
>
> It MIGHT work sort of if you used a sensitive gate
> SCR but that offers a potential for other problems
> like nuisance tripping due to noises on the bus.
>
> The non-sensitive crowbar SCR needs a swift kick in
> the gate to insure a good trigger at all temperatures.
> The simple zener has a soft conduction 'knee' in it's
> V/I curve so is a poor voltage reference at the
> threshold of conduction. Further, the current that
> can be delivered to the gate of the SCR due to
> zener conduction is limited by the source impedance
> of the calibration voltage divider.
>
> The diac has a more predictable trigger voltage
> which produces an avalanche conduction mode that
> dumps the time delay capacitor into the gate
> of the SCR. That pulse is hundreds of mA to
> over 1A. This same characteristic is also desired
> for the triggering of triacs in dimmers . . . the
> #1 commercial use for diacs of any voltage.
>
> See:
>
> http://aeroelectric.com/Pictures/Products/9003_B&C/OVM_14_Prototype.jpg
>
> This was the first crowbar OVM we offered many moons
> ago. This configuration was modified early in
> the production experience to add the 10 ohm gate
> to cathode resistor to negate nuisance tripping.
>
> The diac in this version visible on the left was
> a really cool part. An SD10 as I recall with very
> good tolerances on a 10v trip calibration. This part
> went obsolete and we went to the MBS4991. That part
> went obsolete and I synthesized the diac functionality
> with the pnp/npn pair. At this time, I think B&C has
> both the diac and transistor versions in production
> on the fleet of products. They made a life-time buy
> on the MBX4991. I bought a couple hundred too so that
> I can support my own production though it's probable
> market life. It is similar to this configuration
>
> http://aeroelectric.com/Pictures/Products/9003_B&C/OVM-14_A.jpg
>
> http://aeroelectric.com/Pictures/Products/9003_B&C/OVM-14_B.jpg
>
> except that we now offer a 15 turn calibration potentiometer
> that can be accessed in the field.
>
> This is why the DIY project features the transistor
> pair. But it appears that the new kid on the block
> from Digikey would allow one to fabricate the diac version.
> Your choice.
>
>
> Bob . . .
>
>
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Subject: | Re: Voltage Regulator Problem |
At 11:51 AM 2/21/2011, you wrote:
>
>Bob
>Thanks for clarifying.
>
>With relay circumvented (fat wires disconnected from relay but
>joined together), B+ = 11.6v steady; EIS steady 10.8v. No change to
>either reading with RPM increase.
Okay, this says the rectifier/regulator is bad
>Re the "little wires", neither had voltage with master on ALT.
????? Double failure ???? If there's no power
coming from the alternator switch, then you're
certainly not going to get the alternator on
line.
Trace the power flow from the bus through the
ALT switch to the relay.
Bob . . .
Message 4
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Subject: | Re: Permanent Magnet Alternators - Over Voltage |
Protection
On Mon, Feb 21, 2011 at 12:08 PM, rayj <raymondj@frontiernet.net> wrote:
>
> THIS email is why I love this list. I didn't understand a word of it!!!!
> :)
>
> On 02/20/2011 11:13 PM, Robert L. Nuckolls, III wrote:
>
>> <nuckolls.bob@aeroelectric.com>
>>
>> The non-sensitive crowbar SCR needs a swift kick in
>> the gate to insure a good trigger at all temperatures.
>> The simple zener has a soft conduction 'knee' in it's
>> V/I curve so is a poor voltage reference at the
>> threshold of conduction. Further, the current that
>> can be delivered to the gate of the SCR due to
>> zener conduction is limited by the source impedance
>> of the calibration voltage divider.
>>
>>
I actually read this paragraph to my girlfriend out loud. She said it
sounded like Doc Brown's 1.21 gigawatts flux capacitor speech from Back to
the Future.
I love hanging out with smart people, but I've got a long way to go to
understanding that paragraph. My girlfriend? She said she's going to stick
to biology and leave the electron pushing to me.
do not archive.
--
Andrew Zachar
andrew.d.zachar@gmail.com
Message 5
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Subject: | DIY Over Voltage Protection |
At 12:08 PM 2/21/2011, you wrote:
>
>do not archive
>
>THIS email is why I love this list. I didn't understand a word of it!!!! :)
>
>But if I keep reading this list and studying one day I will.
Absolutely. There was a time when everybody on this List
would not have understood it . . . we all had to
begin somewhere. Suggest you augment your studies with
some hands-on activities that are augmented by discussions
here on the list.
It's a good day when one goes to bed knowing something
you did not know when you woke up that morning. It's
a great day when you can tap the sum of what you've
learned to craft a useful recipe for success. It's
a fantastic day when that recipe can be shared with
others in a way that adds value to their own bag of
tricks.
Knowledge and understanding are the only commodities
I know of that grow in value the more they are given
away. But the process by which you exploit those
opportunities is up to you.
Bob . . .
Message 6
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Subject: | Re: Honeywell Rocker lamp wiring |
You're welcome Jon.
I'm attaching an Excel file that has both my switch and indicator
layout (I don't know if that will post properly on the list so I'm it
directly to you too.) My thinking at the time went something like this:
The first block of 3 switches handles the 2 busses and the buss
crossfeed switch. I assume I will normally fly with first 2 switches on
and the xfeed off so I have a backlit indicator that lights when I turn
it on.
The 2nd block of 4 switches include fuel boost and lights. Again, since
the fuel boost is normally off in flight, I added a lit indicator for
it. The light switches just need to be set and ignored so no indicators
for those other than switch position.
The next 2 switches are for AP navigation source switching and flaps.
Since there really isn't an off or on, no indicator other than switch
position.
I color coded the indicators based on the function. Oil Pressure and
Door are red no-go items, Master Warn (GRT) and Low voltage are yellow
warning items, Buss Xfeed and Fuel boost are green for normal operation
indications.
I have panel dimmers on my panel on my Maule but the switches are unlit
rockers. I end up keeping everything as dim as possible but when I use
a switch, I either do it by memory or I have to turn up the dimmer on
the post lights so I can see the switch. That was my original reason
for going with the backlit Honeywell's.
Two thoughts to consider:
- for night flight, you may not want a light to go bright and stay
that way. The point of dimming them is to improve your night vision so
outside of something you want a warning for, you may not want an
undimmed bright light that stays lit.
- I'm using LEDs in my switches and indicators. Not sure if that's
standard but I think there is an incandescent option. I'm thinking the
LEDs will last forever. In either case, I'm not sure if the dimmer and
voltage implications are different for each type.
Sounds like you are enjoying the electrical stuff as much as I did.
Have fun. Can't wait to fly mine.
Bill "back to masking and painting" Watson
On 2/20/2011 1:24 PM, jonlaury wrote:
> --> AeroElectric-List message posted by: "jonlaury"<jonlaury@impulse.net>
>
> Bill,
> Thanks for your thoughts on wiring the AML series switches. After discussions with Perehelion, I've worked out a scheme to run the switch lamps at 12v (using http://www.semicon.panasonic.co.jp/ds4/AN7712SP_BEB_discon.pdf) for dimming, but when the switch is ON, the lamp gets the bus voltage of 13.5v making them brighter than the dimmer circuit.
> I may have to adjust the max voltage of the dimmer circuit to get the bingo brightness
differential. Or this whole idea may end up in the trash and I simplify
to just hooking the dimmer directly to the lamps like you have done.
>
> John
>
Message 7
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Subject: | Video Inspection Tool |
Deal Extreme has a video Inspection Tool worth considering.
See: http://www.dealextreme.com/p/2-4-lcd-display-inspection-tube-snake-camera-borescope-ntsc-32414
Hey, free shipping. Amazing.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331768#331768
Message 8
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Subject: | Re: Permanent Magnet Alternators - Over Voltage Protection |
> There is a new device (at least new to me!) offered
> by Digikey. See: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=835-1126-1-ND
>
Bob,
I checked out that bilateral switch from Digikey. Unfortunately it is not stocked
and minimum order is 2500 pieces. I did find some other interesting devices
that could be used in an O.V. protection circuit.
http://www.fairchildsemi.com/ds/LM/LM431B.pdf used in this circuit:
http://en.wikipedia.org/wiki/File:Crowbar_Circuit.jpg
And here is a 16.1 volt zener diode that might work in your circuit without voltage
dividing resisters:
http://www.mouser.com/Search/ProductDetail.aspx?R=NZX16B,133virtualkey66800000virtualkey771-NZX16B,133
It might be fun playing around with some of these components. On the other hand,
it is hard to beat the proven circuit that you have provided.
Thanks for your advice.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331769#331769
Message 9
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Subject: | Re: Permanent Magnet Alternators - Over Voltage |
Protection
I've built my own overvoltage crowbar with the MC3423 which is a dedicated
chip for the purpose - very easy to use and cheap enough. See
http://tailwindbuild.blogspot.com/2009/11/15th-november-2009-overvoltage-cro
wbar.html for details
Best regards
Peter
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of user9253
Sent: 21 February 2011 19:37
Subject: AeroElectric-List: Re: Permanent Magnet Alternators - Over Voltage
Protection
> There is a new device (at least new to me!) offered
> by Digikey. See:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=835-1126-1-
ND
>
Bob,
I checked out that bilateral switch from Digikey. Unfortunately it is not
stocked and minimum order is 2500 pieces. I did find some other interesting
devices that could be used in an O.V. protection circuit.
http://www.fairchildsemi.com/ds/LM/LM431B.pdf used in this circuit:
http://en.wikipedia.org/wiki/File:Crowbar_Circuit.jpg
And here is a 16.1 volt zener diode that might work in your circuit without
voltage dividing resisters:
http://www.mouser.com/Search/ProductDetail.aspx?R=NZX16B,133virtualkey668000
00virtualkey771-NZX16B,133
It might be fun playing around with some of these components. On the other
hand, it is hard to beat the proven circuit that you have provided.
Thanks for your advice.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331769#331769
Message 10
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Subject: | Re: Voltage Regulator Problem |
Bob
It is with a very bright red face I offer an apology for the time you've contributed
to my issue. After sending the last note I did as your note suggested--trace
the power from the master switch. After taking the panel out and checking
for connections & current flow I ended up at the circuit breaker. Guess what?
Yes, it had tripped. After resetting the breaker one of the relay "little
wires" showed battery current as you indicated and the regulator B+ showed 14v.
So sorry for not checking the breaker first! Now I'll have to be on the
lookout for whatever caused the breaker to trip the first time. For me it's been
very educational and I thank you.
--------
Frank
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331772#331772
Message 11
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Subject: | DIY Over Voltage Protection |
Bob,
I checked out that bilateral switch from Digikey. Unfortunately it is
not stocked and minimum order is 2500 pieces.
Hmmmm . . . my bad. I jumped on the full range of quanity
pricing starting with "1" but missed the fact that there
were none in stock.
I did find some other interesting devices that could be used in an
O.V. protection circuit.
http://www.fairchildsemi.com/ds/LM/LM431B.pdf used in this circuit:
http://en.wikipedia.org/wiki/File:Crowbar_Circuit.jpg
Emacs!
This is a very rudimentary crowbar ov protection circuit.
It has no provisions for time-delay from onset of
ov condition. The LM431 is an integrated circuit
voltage regulator that can function as a zener
or, as shown above, a comparator. Further,
by adding a couple of resistors, you can calibrate
its switching point.
Out of the box calibration point for the
LM431 is 2.5 volts. So if you're wanting a
16.3 trip point, you can put 2.49K, 1% in
R2 and 13.7K, 1% in R1. You'd need a capacitor
across R2 to establish the cited time delay.
The problem to anticipate is setting a value
for the resistor from Gate to T1 of the triac.
For best noise immunity, it needs to be low,
like 10 ohms or so. Since the LM431 can't
deliver the high current pulse offered by
the legacy avalanche techniques, you may find
that optimum resistance for a good trigger
performance is too high for noise immunity.
When I run out of MBS4991, and assuming I'm
still offering crowbar ov modules, I'll look
at a variation using the LM431.
And here is a 16.1 volt zener diode that might work in your circuit
without voltage dividing resisters:
http://www.mouser.com/Search/ProductDetail.aspx?R=NZX16B,133virtualkey66800000virtualkey771-NZX16B,133
If you can get it to hold tolerance over temperature
range. It's probably a 5% device to start with.
If you hung it from gate to ground, you'd have
to ADD the trigger voltage to the zener value to
deduce the trip point. Both gate and zener
voltage wobble with temperature pretty bad.
The schematic shown above (as modified) is
probably the best experiment to explore.
It might be fun playing around with some of these components.
Sure . . .
On the other hand, it is hard to beat the proven circuit that you
have provided.
The 'proven' circuits HAVE been field tested over
decades of experience and thousands of delivered
products. But virtually all received some degree
of optimization early in their service histories.
The solid state crowbar system proved a practical
for replacing electro-mechanical relays.
But history has repeatedly demonstrated that every
idea is subject to assault from new technologies,
processes and design goals.
Suggest you brass-board your experiments and give
them a try on the bench. You can do some pretty
good tests on effects of temperature using
your freezer.
Bob . . .
Message 12
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Subject: | Re: Video Inspection Tool |
I got one at Harbor Freight built to specs for about $89. Works
great. Also, the monitor is actually removable and has video outputs so
you can tie it into a large screen and/or a recording device. If you
look in the archives, we had a long thread about it a while back.
David M.
Eric M. Jones wrote:
> --> AeroElectric-List message posted by: "Eric M. Jones"<emjones@charter.net>
>
> Deal Extreme has a video Inspection Tool worth considering.
> See: http://www.dealextreme.com/p/2-4-lcd-display-inspection-tube-snake-camera-borescope-ntsc-32414
>
> Hey, free shipping. Amazing.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones@charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=331768#331768
>
>
>
--
If you're an American, just say NO to the Obamanation, to socialism, and get rid
of Soros.
Message 13
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Subject: | Re: Voltage Regulator Problem |
At 03:53 PM 2/21/2011, you wrote:
Bob
It is with a very bright red face I offer an apology for the time
you've contributed to my issue. After sending the last note I did as
your note suggested--trace the power from the master switch. After
taking the panel out and checking for connections & current flow I
ended up at the circuit breaker. Guess what? Yes, it had tripped.
Hmmm . . . something to add to your future
LO VOLTS checklist. Do you have a low volts
warning light? Do you have any notion of when
the alternator was lost and what was happening
at the time?
After resetting the breaker one of the relay "little wires" showed
battery current as you indicated and the regulator B+ showed 14v. So
sorry for not checking the breaker first! Now I'll have to be on the
lookout for whatever caused the breaker to trip the first time.
The legacy ovm designs are 99.9% resistant to transient
events on the system . . . but the reason we
recommend a breaker as opposed to a fuse is that
you can reset it ONE TIME after an OV trip just
to make sure it's a real OV condition and not a
nuisance trip.
For me it's been very educational and I thank you.
Your welcome. Nobody ever promised us that
education was 'cheap' . . . I've had some
expensive epiphanies over the years. Fortunately
none resulted in badly bent airplanes or bodily harm
that wouldn't heal. Lessons hard won at the
expense of $time$ and frustration are those
which are best retained.
The biggest upside of this exchange is that your
particular set of conditions COULD have been
root cause for your own (or somebody else's)
"dark-n-stormy-night" story. By discussing it
here in embarrassing detail means that interested
readers can harvest benefits that few stories in
the flying rags can offer.
Thank you for sharing . . .
Bob . . .
Message 14
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Subject: | Re: Video Inspection Tool |
As these things go, I think you'll find this one is a much better unit. Smaller
head (10 mm) longer reach (90 cm) higher resolutions. Soon they will be perfect
and free.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=331778#331778
Message 15
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Subject: | DIY CBOVM: variations on a theme |
> I am still wondering if a zener diode could be used instead of
> the SBS. If not, it would be interesting to know what the
> disadvantages of the zener diode are, or if it would even work at all.
>Thanks for any advice.
>Joe
Joe,
Feeling adventuresome? I pondered the idea
of exploiting the LM431's precise voltage set
point with a design goal of eliminating the
potentiometer and the post assembly calibration.
Here's what I came up with.
Emacs!
The parts count is unchanged but it should be
calibrated as soon as the last solder joint is
cool. Temperature stability should be as good
or better than any previous versions.
Bob . . .
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