Anyone who is interested in alternate lamps would be thrilled with the
Jade Mountain catalog. It costs $8.00, and has lots of different
flourescents and LED's in a myriad of configurations.
There are a lot of other 12v things too, way more than on the web site.
kept me happy on the throne for a good month.
Daisy
Dr. Gerald N. Johnson, electrical engineer wrote:
>
> I've been doing some studying. My Caravel has three ceiling fixtures,
> each with four 1141 lamps. The rotary switch allows selecting 1, 2 or 4
> lamps at a time, 17, 35, or 70 watts. Each 1141 is rated at 21 candela.
>
> I looked at white LEDs. The largest output I found without digging too
> hard was at Hosfelt Electronics, (www.hosfelt.com), 7000 millicandela,
> or 7 candela. 1/3 the light output of an 1141. The power to the white
> LED is 4 volts at 20 milliamps, .08 watts. Its not a drop in part yet,
> the LED costs $5.99 each and requires current regulation to protect it
> from large changes in current with small changes in voltage. 3 in series
> should be close to working directly from 12 volts with a bit of current
> control. I'm thinking about circuits. The other problem which may be an
> advantage in some applications like reading lamps is that the beam is
> narrow, maybe 28° included angle. For general trailer lighting this
> could be a limitation. There are multiple solutions, the conceptually
> simplest one is a cluster of LEDs each at a different angle to fill in
> the hemisphere of lighting needed for general ceiling lights. I'm
> thinking some sort of spreading lens or reflector or a combination of
> the two might be practical. It might even be practical to defocus the
> dome on the front of the LED. I wasted many red LEDs a few years ago
> trying to make them focus tighter... Dispersion was far easier to
> accomplish.
>
> I've ordered three of the LEDs from Hosfelt. They seem to promise the
> same light level (if it can be spread enough) for 1/100 the power.
> That's far better than the fluorescent fixtures.
>
> Its harder to find fluorescent fixtures using compact fluorescent lamps
> to run off 12 volts. Most use either the 5/8" diameter by 4 to 8"
> tubular lamps or circuline lamps. Neither are great for efficiency or
> commonly available in improved colors, though are very commonly
> available as 12 volt operated fixtures and as replacement lamps.
> Generally the small tubular lamps and compact fluorescent lamps are
> rated at different powers so their ballasts can't be swapped
> successfully.
>
> The first batch of white LEDs should be here about Thursday, then I can
> begin to experiment.
>
> 1141 lamps are on the hooks at Walmart in automotive lights. $1.97 for a
> blister pack of two. There's also 12 volt 18 watt lamps in a similar
> package in the RV section, $.97 for a blister pack of two.
>
> There is a single LED flashlight at Walmart (flashlights are in sporting
> goods) for $11.96. It runs on 2 AA alkaline cells.
>
> Gerald J.
>
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