james(at)etravel.org
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 Posted: Tue Jul 06, 2010 11:15 am Post subject: HLMP-2685 multi-LEDs off LR3C |
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Bob,
Just to feed back to you and anyone on the list who might fancy using
the HLMP-2685 as a snazzy LED alt. warn. light for the LR3C regulator,
I'd like to report the following:
It works quite well putting the 8 LEDs of the HLMP in two parallel
banks of 4 resistors in series, i.e. four LEDs on one side, in series,
put in parallel with the other four LEDs on the other side, those also
put in series. I put a current-limiting resistor of 440 ohms works
well. In fact, it was two 220 ohm resistors in series, but then I
don't have much of a resistor selection...
This arrangement seems to check out okay, and looks to be about the
right brightness. I might tweak it a little bit at some point. When
the warning light is "off", I can't discern any light from the HLMP,
and indeed on the bench I can discern no light from it at 6.0V. For
day time it looks good, though it might also be too bright for night
time use.
FWIW!
Thanks for your guidance on this matter.
James
On Sun, Apr 11, 2010 at 12:28 PM, James Kilford <james(at)etravel.org> wrote:
| Quote: | Bob,
That's great, thank you. It gives me a good place from which to experiment.
James
On Thu, Apr 8, 2010 at 2:04 PM, Robert L. Nuckolls, III
<nuckolls.bob(at)aeroelectric.com> wrote:
>
> <nuckolls.bob(at)aeroelectric.com>
>>
>>
>> http://parts.digikey.com/1/parts/681506-led-lt-bar-hi-eff-red-8led-dip-hlmp2685.html
>>
>> I'd like to hook one of these to the LR3C regulator instead of the
>> supplied filament lamp, so that it can go into the annunciator panel
>> too.
>>
>> I've been trying to trace a schematic of Bob's, which I'm sure I've
>> seen, of how to use an LED instead of a filament lamp with the LR3C,
>> as a starting point. I can't find it, and the resistor values would
>> be different in any case, so can anyone throw any light on to how to
>> use one of these 8-LED devices with the LR3C?
>
> The schematic I published is at:
>
> http://aeroelectric.com/Pictures/Schematics/LR3_LV_Led_1.jpg
>
> Your application will take some experimentation.
> You can try paralleling all the LEDs and seeing how
> well you can excite the array and still have uniform
> illumination. You may find that you need to treat
> them as separate LEDs.
>
> Just be aware that LR3 lamp driver is never completely
> "OFF". The off current is too low to get any light
> from a bulb but it will cause an LED to glow at a
> reduced intensity. Hence the paralleling resistor to
> get the LED to mimic a lamp more closely.
>
> Bob . . .
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