Instrument backlighting mandatory ?

Hi All,

I have a TB20 (an IFR certified aircraft) and wish to fit a backup oil
pressure gauge.

The instrument I am putting in is the miniature 1.2" TSOd one from UMA
Instruments. It is done as a minor mod and the IA doesn't see a
problem.

However, the backlighting is implemented with an electroluminescent
element inside the instrument, and requires a separate inverter. I
have this too (it isn't TSOd but is PMAd) and while it works, it draws
a lot of power (2.5 watts) which is dissipated mostly inside the
inverter, making it run hot, so it needs to be mounted to the airframe
or something similar. This is also OK, but I am concerned about the
emissions from the inverter and its wiring: it generates about 300V
RMS at about 2.5kHz and the output waveform isn't exactly clean, and I
am concerned about some subtle effect on other avionics. Obviously all
wiring will be screened but one can never tell.

In short, do I *have* to install this inverter? Is a backlight
mandatory on a backup instrument?

What about connecting the inverter via a switch?

Why they just didn't use some LEDs I don't know........

"Kobra" <kobra@*****.net> wrote

> All my engine and fuel gauges are unlit. I hate it. I bought an AOPA
> headstrap LED light some time ago. What works better than wearing it
> is....I removed the headstrap, put a small piece of Velcro on the bottom
> of the light and stuck in on the top of the Garmin 396 yoke mount. When I
> fly at night I click it on and it flood-lights the entire engine and fuel
> gauges. The battery has held up for two years now. My only complaint is
> that it doesn't appear to have the ability to open the case and replace
> the battery without damaging the unit. I think it was only a few dollars
> anyway.

Why not get some red led's, and rig up some glareshield lighting for the
gages?

Not too hard to wire, or mount, I would think.
--
Jim in NC