Today's Message Index:
----------------------
1. 01:06 AM - Re: LED Ghosting (donjohnston)
2. 03:57 AM - Re: LED Ghosting (user9253)
3. 06:38 AM - Re: Re: LED Ghosting (Charlie England)
4. 07:56 AM - Re: LED Ghosting (donjohnston)
5. 10:07 AM - Re: LED Ghosting (user9253)
6. 10:08 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III)
7. 11:21 AM - Re: Re: LED Ghosting (Roger & Jean)
8. 11:24 AM - Re: Re: LED Ghosting (Robert L. Nuckolls, III)
9. 12:07 PM - Re: LED Ghosting (donjohnston)
10. 12:36 PM - Re: Re: LED Ghosting (rayj)
11. 01:26 PM - Re: Re: LED Ghosting (Lyle Peterson)
12. 02:44 PM - Re: LED Ghosting (donjohnston)
13. 04:29 PM - Re: LED Ghosting (user9253)
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Subject: | Re: LED Ghosting |
Yep.
"The engine analyzer people said it was designed for incandescent and to put a
1.5k resistor across the LED. "
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=424993#424993
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Subject: | Re: LED Ghosting |
Does the LED have a series resistor? If so, what is its value?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=424997#424997
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Subject: | Re: LED Ghosting |
On 6/17/2014 3:04 AM, donjohnston wrote:
>
> Yep.
>
> "The engine analyzer people said it was designed for incandescent and to put
a 1.5k resistor across the LED."
>
>
What kind of LED are you using? Is it one designed to run directly on
12V (meaning it already has an internal current limit resistor)?
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Subject: | Re: LED Ghosting |
> Does the LED have a series resistor? If so, what is its value?
> Joe
Yes. 390ohm (see attached).
What kind of LED are you using? Is it one designed to run directly on 12V (meaning
it already has an internal current limit resistor)?
No. See above.
There's nothing wrong with any of the other LEDs. It's just the one for the engine
analyzer. The analyzer is allowing some current through when it's off. With
an incandescent bulb, this is not a problem. With an LED, it is. Putting a
1k resistor solves the dimly lit LED but it make the LED dimmer than the rest.
So I'm trying to solve two possible problems. 1) Keep the engine analyzer alarm
LED from being partially lit when it should be off, and 2) have the LED at
the same brightness as the other LEDs.
Now it's possible (more like probable) that I'm going to have the exact same problem
with the Low Voltage warning since the LR3C voltage regulator is designed
for an incandescent bulb also. But I haven't gotten to the point where I can
start the engine so I don't know yet.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425013#425013
Attachments:
http://forums.matronics.com//files/warning_circuit_109.pdf
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Subject: | Re: LED Ghosting |
I suggest that you put a 1.5k resistor across the LED per the engine analyzer people.
Then replace the 390 ohm series resistor with a 330 ohm resistor. Or
experiment with different values (all less than 390) to get the desired brightness.
Or put a pot in series with the dim LED and turn the pot until the current though
the dim LED is equal to the current through one of the other LEDs. Then substitute
a fixed resistor for the pot.
40 years ago I could have calculated the resistor value. Now trial and error is
easier. :-)
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425024#425024
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Subject: | Re: LED Ghosting |
At 09:55 AM 6/17/2014, you wrote:
>
>
> > Does the LED have a series resistor? If so, what is its value?
> > Joe
>
>Yes. 390ohm (see attached).\
Ooops, two LED's in series . . . should have asked about
that. Okay, I suggest we pay homage to our teachers one
of whom once opined: ". . . when you can measure what you are
speaking about, and express it in numbers, you know something
about it; but when you cannot measure it, when you cannot
express it in numbers, your knowledge is of a meagre and
unsatisfactory kind; it may be the beginning of knowledge,
but you have scarcely in your thoughts advanced to the state
of Science . . ." -Lord Kelvin-
Consider the array of sketches at:
http://tinyurl.com/oxrwae7
. . . it would be exceedingly helpful to conduct three
experiments to measure V1 (voltage across the bare-foot
resistor/led array; V2 (voltage across incandescent
lamp); V3 voltage across resistor/led array with anti-
ghosting resistor added.
>There's nothing wrong with any of the other LEDs. It's just the one
>for the engine analyzer. The analyzer is allowing some current
>through when it's off. With an incandescent bulb, this is not a
>problem. With an LED, it is. Putting a 1k resistor solves the dimly
>lit LED but it make the LED dimmer than the rest. So I'm trying to
>solve two possible problems. 1) Keep the engine analyzer alarm LED
>from being partially lit when it should be off, and 2) have the LED
>at the same brightness as the other LEDs.
>
>Now it's possible (more like probable) that I'm going to have the
>exact same problem with the Low Voltage warning since the LR3C
>voltage regulator is designed for an incandescent bulb also. But I
>haven't gotten to the point where I can start the engine so I don't know yet.
Can't speak to internals of the engine analyzer but
the LR3 regulator has a lamp output driver
http://tinyurl.com/cgnwr5k
INTENDED to exhibit some pull-down current on the
lamp even when the LR-3 internal electronics are UN
powered . . . The circuit above was suggested to soak
off the effects of this small 'leakage' current that
was insufficient to light an incandescent lamp but
enough to tickle an LED into a small light output.
I suspect a similar thing is happening with the engine
analyzer.
You can test the LV warn from the LR3 without running
the engine. The light starts to flash as soon as you
turn on the master switch even if the alternator is
off and/or the engine is not running.
Get those voltages and we can begin to sort out your
current difficulty.
Lord Kelven was also known to have said things like
"I believe x-rays will prove to be a hoax" . . . and
"There is nothing new to be discovered in physics
now. All that remains is more and more precise measurement."
These blunders by the venerable gentleman serve to remind
us that the good student questions everything and seeks
to sort un-substantiated opinion from demonstrable fact.
Let us go to the workbench and demonstrate . . .
Bob . . .
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Subject: | Re: LED Ghosting |
> Does the LED have a series resistor? If so, what is its value?
> Joe
Yes. 390ohm (see attached).\
Perhaps you could use a zener with a voltage just slitely
higher than the open circuit off voltage output. Put that in
series with the LED, to block the small output, and reduce t
he series resistor to bring the brightness up.
Roger
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Subject: | Re: LED Ghosting |
>
>
> You can test the LV warn from the LR3 without running
> the engine. The light starts to flash as soon as you
> turn on the master switch even if the alternator is
> off and/or the engine is not running.
Stubbed my toe here . . . of course without the
engine running, you'll have to boost bus voltage
with an ac mains power supply to get the light to
go out . . . hence, without that power supply you
are correct, exercising the LR-3's lv warning is not
yet possible.
However, the LR-3 is intended to drive lamps with
over 100 mA of operating current. So the schematic
I suggested for one led MIGHT still be good for two
but in any case, the configuration shown for the
V3 measurement is good . . . the 1K resistor is
simply reduced in value until the ghost-light
goes out. So hooking your annunciator to the un-powered
LR-3 should offer a platform for validating the
value of the anti-ghosting resistor.
Bob . . .
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Subject: | Re: LED Ghosting |
user9253 wrote:
> I suggest that you put a 1.5k resistor across the LED per the engine analyzer
people. Then replace the 390 ohm series resistor with a 330 ohm resistor. Or
experiment with different values (all less than 390) to get the desired brightness.
> Or put a pot in series with the dim LED and turn the pot until the current though
the dim LED is equal to the current through one of the other LEDs. Then
substitute a fixed resistor for the pot.
> 40 years ago I could have calculated the resistor value. Now trial and error
is easier. :-)
> Joe
I tried that. I ended up with no series resistor and it was still dimmer than the
others.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425032#425032
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Subject: | Re: LED Ghosting |
How about a brighter led, so it's dimmed level will be equal to the others.
Raymond Julian
Kettle River, MN
The things we admire in men, kindness and generosity, openness, honesty,
understanding and feeling are the concomitants of failure in our system.
And those traits we detest, sharpness, greed, acquisitiveness, meanness,
egotism and self-interest are the traits of success. And while men
admire the quality of the first they love the produce of the second.
-John Steinbeck, novelist, Nobel laureate (1902-1968)
On 06/17/2014 02:06 PM, donjohnston wrote:
>
>
> user9253 wrote:
>> I suggest that you put a 1.5k resistor across the LED per the engine analyzer
people. Then replace the 390 ohm series resistor with a 330 ohm resistor.
Or experiment with different values (all less than 390) to get the desired brightness.
>> Or put a pot in series with the dim LED and turn the pot until the current though
the dim LED is equal to the current through one of the other LEDs. Then
substitute a fixed resistor for the pot.
>> 40 years ago I could have calculated the resistor value. Now trial and error
is easier. :-)
>> Joe
>
>
> I tried that. I ended up with no series resistor and it was still dimmer than
the others.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=425032#425032
>
>
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Subject: | Re: LED Ghosting |
I don't believe you will get satisfactory results with any combination
of resistors. I think the only solution is a driver circuit between the
output and the LED. A single transistor and a couple of resistors should
do it. It may need a separate power source.
On 6/17/2014 2:06 PM, donjohnston wrote:
>
>
> user9253 wrote:
>> I suggest that you put a 1.5k resistor across the LED per the engine analyzer
people. Then replace the 390 ohm series resistor with a 330 ohm resistor.
Or experiment with different values (all less than 390) to get the desired brightness.
>> Or put a pot in series with the dim LED and turn the pot until the current though
the dim LED is equal to the current through one of the other LEDs. Then
substitute a fixed resistor for the pot.
>> 40 years ago I could have calculated the resistor value. Now trial and error
is easier. :-)
>> Joe
>
> I tried that. I ended up with no series resistor and it was still dimmer than
the others.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=425032#425032
>
>
--
Lyle
Sent from my Gateway E4610D desktop
Message 12
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Subject: | Re: LED Ghosting |
nuckolls.bob(at)aeroelect wrote:
>
> Ooops, two LED's in series . . . should have asked about
> that. Okay, I suggest we pay homage to our teachers one
> of whom once opined: ". . . when you can measure what you are
> speaking about, and express it in numbers, you know something
> about it; but when you cannot measure it, when you cannot
> express it in numbers, your knowledge is of a meagre and
> unsatisfactory kind; it may be the beginning of knowledge,
> but you have scarcely in your thoughts advanced to the state
> of Science . . ." -Lord Kelvin-
>
> Consider the array of sketches at:
>
> http://tinyurl.com/oxrwae7 (http://tinyurl.com/oxrwae7)
>
I suggest we pay homage to our teachers one of whom once replied: "Dammit Bob,
I'm a doctor, not a engineer" -Dr. Leonard McCoy-
Unfortunately, this is a bit beyond my skillset. While the squiggly lines are not
quite hieroglyphics to me, I'm not exactly sure what to do with them.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425043#425043
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Subject: | Re: LED Ghosting |
OK, here is another idea. Put a diode (1N4148 ?) in series with each of the bright
LEDs. If you are lucky, the voltage drop across the 1N4148 will equal the
voltage drop across the oil pressure solid state switch.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=425054#425054
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