Lighting for chart table

[KG8]

I have built a low table (1.5 meter square) for my charts and log book but the lighting I have for it seems inadequate. At present I have a light weight pedistal lamp that I converted from 240V to 12 by removing the transformer from its base, fitting a NiCad pack, and a suprbright led up top to replace the halogen bulb in the lamp head. I put a variable resistor into the head also and it can give a reasonable amount of light but it only casts the light in a small 12 inch circle, as leds do.

Can anyone suggest anything that would give me a wider band of light? I can add extra leds to the head and angle them apart, but the pattern they create on the charts is a little confusing and distracting. I was hoping there would be a better way.

[acropolite]

A lens in front of the LED may give the desired effect, the energiser headlights have a small lens in front of each led to focus the beam.

[duncan]

Hi all,
As yet i haven't had anything to do with this sort of thing but how would a 12 volt fluoro painted red go? You could even put a reflective cover over it like a desk lamp. Just a suggestion from a newbie.
Cheers,
Duncan

[Dennis]

Hi K8

Have a look at this IIS article (http://www.iceinspace.com.au/index.php?id=63,370,0,0,1,0)describ ing a portable observing hutch (http://www.iceinspace.com.au/index.php?id=63,370,0,0,1,0).

Figure 1 shows a single fluoro light with a red gel filter that provides a large area of even illumination. The red gel filter was cut from a sheet of stage lighting filter material, so it is quite tough.

Figures 2 and 15 show daylight views of the fluoro, which is mains operated.

Cheers

Dennis

[KG8]

Food for thought there... I'll suss out the fluros and see how much power they drain. Last night I knocked up a small EP tray illuminator by attaching a small superbright led to a AA battery holder box, I will velcro it to one of the tripod legs above the EP's. Anyway I needed a similar sort of 'diffuse' light spread but dim and I found if I jamed the led into the end of a white plastic 2pin teminal plug (using it as a sort of holder come lens) I got a nice even spread of dim red light :) A 560ohm resistor was needed to do the dimming and there is some alfoil on the back and end of the plug. It's a lot dimmer than the camera made it look.
http://img.villagephotos.com/p/2006-1/1141581/redlamp.jpg

Perhaps I could mount 2 large superbrights in opposite ends of a translucent plastic "something or other" as a solution.

I like the hutch, I like the waterproof cover idea and think I will make something similar. Thank you for the input guys!

[RAJAH235]

Why not try one of these CCFL tubes? Come in RED as well. They cannot be 'control dimmed' tho.
Could be diffused/dimmed by installing in a small box, (for mechanical protection), etc with diffuser/filter material in front.
> http://www1.jaycar.com.au/productView.asp?ID=SL2860&CATID=&keywords=sl%2D2860&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=
> http://www1.jaycar.com.au/productView.asp?ID=SL2868&CATID=&keywords=sl%2D2868&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=
Should give a nice overall light, & fairly low on power consumption.
HTH. :D L.

[KG8]

500mA, don't know if I want to go that far RAJAH. I'm trying to keep power consumption to a minimum so I can stay longer with less battery power. Thanks for your efforts though, I will pick up a couple next time I'm up at Jaycar as They are perfect for some other projects I have in the shed. Can't go wrong for $12 and a lot more efficient than converting 240V fluros down the 12V.

[GTB_an_Owl]

i think you will find the flouro's are not very red

geoff

[KG8]

I grabbed one of the red ones RAJAH and found that placing a large 28ohm resistor in series before the circuit dropped it's power consumption to a respectable 100mA. the light output also dropped quite nicely (it was a little too bright at full power) At these low currents though the tube has a little trouble starting sometimes, so I put a little single-pole push switch in to bypass the resistor and allow the full current to be applied to the circuit when this happens. I have no idea if the reduced power will effect the circuit or tube negatively but I will give it a 10 hour test once it's mounted in some form of lamp arrangement.
Thanks for the idea!

[RAJAH235]

You're welcome.
The tubes should last heaps longer running on the lower input.
Shouldn't hurt the electronics either.
They do run very bright tho., as you found out.
Usually used to illuminate 'modded' cars n 'pimp' mobiles. :D L.