adding instrument light/backlight

[William G. Andersen]

Anyone have ideas about how to add a light/backlight to an instrument?
I want to add interior illumination to the display panel of my Si-Tex 525
ADF. It has three lights for operation and they're very bright: I think it
would be easier on my eyes at night if the face of the panel was softly
illuminated. Si-Tex only states they don't offer an illumination mode.
I'm thinking of a small 12 volt bulb inserted in a notch on one edge -
thinking the light would be distributed through the clear panel.
An alternative would be to just mount one or two bulbs inside the case so
that the bulbs aren't directly visible, but so that the light would be
dispersed throughout the case.
In either case, I plan on wiring the bulb(s) to the power switch of the ADF.

 

[Robert Miles]

I would've thought that LED's would be better than bulbs.. last longer ..

Regards

 

[William G. Andersen]

But aren't LEDs very focused, directional light? I'm hoping for a soft
illumination - not another bright light.

 

[Brent Geery]

But aren't LEDs very focused, directional light? I'm hoping for a soft
illumination - not another bright light.

Some LEDs are focused, some are defused. Worst case, you simply take
the focused LEDs and work on them a little with some sand paper (or a
sand blaster, if you have access to a small one.)

 

[Glenn Ashmore]

An LED will disburse throughout a sheet of plastic and show up brightest at
any scratches, printing or other deformities in the surface. OTOH, if the
display is an LCD any light in front of the LCD array will make it a lot
harder to read. You have to light LCD displays from behind. That is
usually done by placing a frosted edge lit acrylic sheet or
electroluminecent panel behind the LCD array.

 

[William G. Andersen]

Thanks for the information...now I need to take the time to open the case
and see what I can do.

 

[Len Krauss]

I had a similar issue with lighting for two fuel gauges. I rewired the bulbs
to be in series which cut the brightness considerably. Also painted bulbs
red -- used special paint for this designed to take heat. Theatrical supply
places have it as do some mail order auto supply places. If you get lucky
you may actually be able to buy the right bulbs already colored red.
Len

 

[William G. Andersen]

Colored light bulbs are no problem. I painted the original bulbs in my
instrument lights with nail polish. The next week I saw colored light bulbs
in WalMart - very inexpensive.
So now I just need the time to take the display out of the boat and tinker
with it. I boat at least twice a week, so it may be a while before I have
the time...
My boat: http://members.cox.net/wgander/family_boat.htm

 

[Len Krauss]

Be careful with nail polish to color incandescent bulbs, which I assume you
have. Some get quite hot, esp the bright ones. When I was a kid I did the
nail polish thing on boat instrument bulbs, and it gave off smoke that
clouded the instrument lenses. As these were sealed, the lenses couldn't be
cleaned. Instruments were still readable, but the cloudy appearance of
lenses wasn't pleasing.

 

[William G. Andersen]

When I saw how inexpensive the red bulbs were at WalMart, I bought enough to
replace all of the light bulbs I painted and have a few more as spares.