Re: ? on small battery operated fluorescents

Recently found a couple of these at my local electronics candy store...

http://www.logical-lighting.com/pdf/LEDHPModuleWhitePDF.pdf

and built an emergency lantern out of them, using a couple of six-cell AA
holders and a 7812 voltage regulator. It's not very impressive though, and
I was thinking of doing something similar with the two LEDs for the
flashlight and a fluorescent tube down the side, with a three-position
rocker switch to select which funcion is activated. Would love it if
someonecould point me in the right direction for something like this. Do
appreciate the help so far...

Dave

Unless you have a severe itch to proceed with local parts, I don't see
why you'd use that.
Also, I hate to see something running off battery power using a linear
regulator, unless this project is only about cheapest way with parts
you have on hand.

For a replacement to something that lasted 20 years, I think you
deserve more. As always, with a simple circuit homebrew product the
trickiest part isn't the parts as much as the case, what is reasonable
to use instead of being a chunky box when it comes to a flashlight
that has to satisfy a significant other.

You have not listed all your design requirements, so there isn't an
easy answer. One popular alternative among mountain biking circles is
to make the body of the flashlight out of tubular or square/
rectangular aluminum, then the body of the light becomes the heatsink
and the driver board, then for handheld use.. plus cells (battery) is
contained within. One caveat with this type of design is if the
handle is a heatsink, if it runs for a few minutes it starts to get
hot at higher current levels. Size becomes one of the design
criteria.

When it comes to implementing a driver board and LEDs, the sky is the
virtual limit on how you want to shoe-horn these into a finished
product if you only keep the cooling vs current requirements per light
output in mind. Basically, I suggest you try the modern Cree XR-E
LEDs, with a driver board that suits your average voltage for whatever
battery you want to use, then as far as the rest of the housing, it's
up to your imagination so long as you remember to keep the heatsinking
reasonable for the driving current used. More light requires a larger
flashlight, though all else being equal, the more LEDs you use, the
more investment in buying more per the light output you want, the
resultant lower drive current will reduce the size of the heatsink you
need since you reduce the heat density per LED. Driving XR-E's at
350MA per seems to be a sweet spot for good efficiency vs cost, but
this still requires at least a minimal heatsink.
--

sigh Am just beginning to realize the complexity of what I originally
imagined to be a simple and quick throw-together. No easy answers. Would
like to make use of some type of flashlight bulb (krypton?) that would
tolerate the 18V my battery pack offers when fresh, and would continue to
function in some fashion as it dropped down below 12V. Would also like to
run an 8-watt fluorescent off of the same battery pack as long as possible
(Possibly this one?
http://www.newark.com/cec-industries/f8t5-cw/fluorescent-lamp/dp/85K9048?_requestid=96321).

Would *like* to make use of the same battery pack I am currently using
simply because it fits the hand well and represents the *approximate*
desired finished size (+/- 8" x 1.25" x 1.25"). Would like to run the
fluorescent down one side of this battery back. I imagine sealing the
electronics in the insulative, industrial sealant/craft adhesive E-6000,
leaving whatever heatsink is necessary outermost on the end away from the
flashlight bulb/reflector. Would like to use a three-position rocker switch
to select between the two lighting functions.

What, in your opinion, would be the best way to achieve the 120VAC required
by the aforementioned fluorescent bulb for as long as possible? Stick with
a 12VDC regulator, and run the output through a switching power supply for
X10 output?

You mentioned Cree XR-E LEDs. The Q5 does look promising. Is this the
5-watt LED that I hear about at my electronics candystore? And what,
actually, is involved in designing a driver board? Would these compare at
all with a Krypton bulb? Or is that simply a trade-off one weighs,
brightness for current drain?

All I can think of right now. Really appreciate your patience, and help.
Sorry for the long-drawn out post...

Dave





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