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Mark Phillips in TN
Joined: 10 Jan 2006 Posts: 431 Location: Columbia, TN
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Posted: Thu Nov 09, 2006 3:42 pm Post subject: Transistorture |
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Howdy those-that-know-
I am (as usual) trying something I know little about, but he'p me out here, purty please!
Goal: light an annunciator LED when Trutrak servos are OFF. This is a reminder that Digiflight is not flying the airplane. Normal condition is A/P on for normal flight with LED OFF.
Suggestion from Trutrak: connect NPN Darlington transistor base via a 10K resistor to servo torque line on servo connector (pin 6- common to pin 4 or 16 on back of Digitrak depending on pitch or roll servo) . Connect 12v to annunciator LED+, LED ground to emitter and use transistor collector to ground lamp. If I got this right, the signal from the servo turns transistor on, completing LED circuit, LED comes ON.
Problem is, Trutrak offered no guidance beyond "Darlington NPN transistor" and I have googled, Digikeyed & Mousered trying to find an appropriate transistor. The values are mystifying and require much research & education to demystify. Best quess is this one in a TO-92 package:
http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=488&M=2N6426G
Supposing this is a good choice to turn the LED ON, can I turn the LED OFF by using this transistor circuit to turn on a small relay and use relay N.C. contacts connected to LED ground to turn off the LED when servo is energized, and if so, what would be an appropriate relay?
Or is there a better way to do this?
I humble myself before y'all but THANKS just the same for any advice!
Mark Phillips
[quote][b]
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nuckollsr(at)cox.net Guest
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Posted: Fri Nov 10, 2006 5:09 am Post subject: Transistorture |
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Who did you talk to there? Was it on phone or by e-mail.
We could take a pretty good guess at what's being suggested
but it would be best to have a more pointed conversation with
them. If you can help me contact the right person, I'll see
if I can get a better definition of the task.
Bob . . .
At 06:39 PM 11/9/2006 -0500, you wrote:
Quote: | Howdy those-that-know-
I am (as usual) trying something I know little about, but he'p me out
here, purty please!
Goal: light an annunciator LED when Trutrak servos are OFF. This is a
reminder that Digiflight is not flying the airplane. Normal condition is
A/P on for normal flight with LED OFF.
Suggestion from Trutrak: connect NPN Darlington transistor base via a 10K
resistor to servo torque line on servo connector (pin 6- common to pin 4
or 16 on back of Digitrak depending on pitch or roll servo) . Connect 12v
to annunciator LED+, LED ground to emitter and use transistor collector to
ground lamp. If I got this right, the signal from the servo turns
transistor on, completing LED circuit, LED comes ON.
Problem is, Trutrak offered no guidance beyond "Darlington NPN transistor"
and I have googled, Digikeyed & Mousered trying to find an appropriate
transistor. The values are mystifying and require much research &
education to demystify. Best quess is this one in a TO-92 package:
<http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=488&M N6426G>http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=488&M N6426G
Supposing this is a good choice to turn the LED ON, can I turn the LED OFF
by using this transistor circuit to turn on a small relay and use relay
N.C. contacts connected to LED ground to turn off the LED when servo is
energized, and if so, what would be an appropriate relay?
Or is there a better way to do this?
I humble myself before y'all but THANKS just the same for any advice!
Mark Phillips
www.aeroelectric.com
<http://www.buildersbooks.com>www.buildersbooks.com
<http://www.matronics.com/contribution>http://www.matronics.com/contribution
<http://www.matronics.com/Navigator?AeroElectric-List>http://www.matronics.com/Navigator?AeroElectric-List
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Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
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Mark Phillips in TN
Joined: 10 Jan 2006 Posts: 431 Location: Columbia, TN
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Posted: Fri Nov 10, 2006 5:33 am Post subject: Transistorture |
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In a message dated 11/10/2006 7:16:37 AM Central Standard Time, nuckollsr(at)cox.net writes:
Quote: | Who did you talk to there? Was it on phone or by e-mail. |
>>>
Request was made by phone to John (dangit, do not recall last name) and attached .pdf sent via e-mail in reply. Will monitor list to see if attachment gets through, if not, will e-mail direct.
Thanks!
Mark do not archive
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nuckollsr(at)cox.net Guest
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Posted: Fri Nov 10, 2006 6:44 am Post subject: Transistorture |
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At 08:32 AM 11/10/2006 -0500, you wrote:
Quote: | In a message dated 11/10/2006 7:16:37 AM Central Standard Time,
nuckollsr(at)cox.net writes:
Who did you talk to there? Was it on phone or by e-mail.
>>>
Request was made by phone to John (dangit, do not recall last name) and
attached .pdf sent via e-mail in reply. Will monitor list to see if
attachment gets through, if not, will e-mail direct.
Thanks!
Mark do not archive
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The schematic helped. See attached .pdf
All parts are available from Radio Shack. You can wire
two ways. One version turns LED ON when servo signal high,
the other turns it OFF.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
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Mark Phillips in TN
Joined: 10 Jan 2006 Posts: 431 Location: Columbia, TN
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nuckollsr(at)cox.net Guest
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Posted: Sat Nov 11, 2006 5:02 am Post subject: Transistorture |
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At 07:46 PM 11/10/2006 -0500, you wrote:
Quote: | In a message dated 11/10/2006 8:47:51 AM Central Standard Time,
nuckollsr(at)cox.net writes:
The schematic helped. See attached .pdf
Amazing- once again you have taught and assisted beyond all expectations-
circuit B puts LED supply to ground potential for the big turn off! This
is too cool- lots of uses for this, time ta git busy (gotta figure out
packaging)...
THANK YOU SIR!!!
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You're most welcome. Consider "potting".
Small circuits like this can be simply
spider-webbed together, checked for function
and then potted in epoxy using just about
any form of the right shape and volume.
Since the epoxy offers the structural
integrity, the enclosure need only hold things
in place until the epoxy sets up.
bundle the wires and put a sleeve of heat
shrink over them so that there is some
bend relief offered by the shrink where
the wires exit the epoxy.
Avoid fast setting epoxies . . . all epoxies
warm up and the large volume applications
using fast epoxy may get so hot as to boil
over. Get some long pot life stuff, 30 minutes
or more and it will probably work just fine.
Once your circuit is suitably ensconced in
plastic, you can bond a mounting plate to
the bottom with E-6000.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
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Mark Phillips in TN
Joined: 10 Jan 2006 Posts: 431 Location: Columbia, TN
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Posted: Sat Nov 11, 2006 11:10 am Post subject: Transistorture |
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In a message dated 11/11/2006 7:05:12 AM Central Standard Time, nuckollsr(at)cox.net writes:
Quote: | Consider "potting". |
Got it, thanks again!
Mark do not archive
[quote][b]
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dsvs(at)ca.rr.com Guest
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Posted: Sat Nov 11, 2006 9:14 pm Post subject: Transistorture |
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Bob,
I would like to use a transistor to convert a normally open switch to
normally closed. I need to switch a circut ground off. This would be very
simple with a relay, but, I would like to use a transistor if this can be
done. Is this a reasonable approach? If yes can you draw me a diagrtam?
Thanks.
--
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nuckollsr(at)cox.net Guest
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Posted: Mon Nov 13, 2006 5:41 am Post subject: Transistorture |
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At 09:14 PM 11/11/2006 -0800, you wrote:
Quote: |
Bob,
I would like to use a transistor to convert a normally open switch to
normally closed. I need to switch a circut ground off. This would be very
simple with a relay, but, I would like to use a transistor if this can be
done. Is this a reasonable approach? If yes can you draw me a diagrtam?
Thanks.
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Can you sketch the surrounding circuitry? Do you have access to
both ends of "the switch" or is one end already connected to
ground . . . or perhaps 12v? What do you what the output to control?
Bob . . .
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dsvs(at)ca.rr.com Guest
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Posted: Mon Nov 13, 2006 9:40 am Post subject: Transistorture |
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The circuit is just a ground to tell my TCAD that it is on the ground. A
pressure switch ( I can only find NO in the range I need) is in the pitot
system. The switch closes at roughly 50 knots. I have access to both ends
of the switch. The switch is a micro pneumatic logic 503. Maybe you know a
supplier that would sell me one that is NC.The closing of the switch is
supposed to open the ground on the TCAD. I can easily convert the no to nc
by using a relay, but, I thought a transistor may also work?? Just making
an attempt to learn more electric stuff. I hope that this explanation
works.
--
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nuckollsr(at)cox.net Guest
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Posted: Wed Nov 15, 2006 6:32 am Post subject: Transistorture |
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At 09:40 AM 11/13/2006 -0800, you wrote:
Quote: |
The circuit is just a ground to tell my TCAD that it is on the ground. A
pressure switch ( I can only find NO in the range I need) is in the pitot
system. The switch closes at roughly 50 knots. I have access to both ends
of the switch. The switch is a micro pneumatic logic 503. Maybe you know a
supplier that would sell me one that is NC.The closing of the switch is
supposed to open the ground on the TCAD. I can easily convert the no to nc
by using a relay, but, I thought a transistor may also work?? Just making
an attempt to learn more electric stuff. I hope that this explanation
works.
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If we knew more about the internal wiring of the TCAD system, perhaps
the solution could be as simple as the first sketch below.
1a352a.jpg
However, the second sketch is 99.9% certain to work. All the parts are
available from Radio Shack.
Bob . . .
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