(Editor's Note: A "first" has happened with our Hints For Homebuilders column - an EAA member submitted a hint for both categories. The hints - electrical and technical - were

sent to the different judges and were given high ratings by all. Congratulations to Ingeborg L. Ray, EAA 237588, 2546 W. Village Dr., Phoenix, AZ 85023-2250, for her big win!)

ANNUNCIATOR LIGHT DIMMING We homebuilders like to incorporate a lot of neat features in our planes. Many of these are special annunciator lights that warn us of danger. I have five of them in my Glasair. One problem with annunciator lights is that they need to be bright enough to see in the day, but dim enough so they don't blind you at night. The conventional solution for this problem is to use an adjustable iris over the light. Not only is this very big, it's also very expensive! But homebuilders are anything but

conventional! We're always looking for a better solution. Piper was on the right track when they had the gear lights in their aircraft automatically dim when the NAV lights were on.

They did it mechanically. We can do it electrically. And that's what this simple circuit does. The heart of the circuit is the LM317 adjustable voltage regulator. That circuit and its construction were explained in an article by Bob Nuckolls in the June 1993 issue of SPORT AVIATION. By adding just a few more

parts, we can make this circuit automatically dim annunciator lights for us when we turn on the NAV lights. Basically, all this circuit does is use a transistor to bypass the LM317 when the NAV lights are off. When they are on, the transistor turns off, and the LM317 takes over. Mine is set for about 6 volts, which was just the right voltage to make my annunciator lights right for night. All parts are available at Radio Shack. The transistor is P/N 2762023. Total cast? less than $10!

Add|ticina^Circuitry _

NAV Light Switch

2N2907

Annunciator Lights

Switched Grounds from Annunciator circuitry

Solid State Light Dimmer Circuit from June 93 Issue 92 APRIL 1995

PAINT HINT We chose to paint my Glasair in three colors. Ordinarily, the fastest and easiest way to do this is to simply paint one color over another. But that won't do for a Champion homebuilt anymore! Grand Champions at Oshkosh, starting with Myron Jenkins, have set a higher standard. The problem with painting one color over another is that a ridge forms as one layer of paint builds on another. Even if you clear coat, as we plan to do later, you can still feel the paint ridges below the clear even if you color sand.

paint creep could really ruin my job.

Then we got a hint from the president of my local EAA Chapter. He had the same problem painting his RV-6. He suggested setting the spray gun for a small, light pattern, and making a quick pass over the tape line before spraying the tack

mask everywhere on the plane where the

coat. This has the effect of sealing the tape in preparation for the next coats. We weren't comfortable with this technique because we weren't good enough with the gun to spray fast, light and wet. We didn't want the paint to go on dry, because the brand of paint we used was very unforgiving of any previ-

let it dry, take off the mask, re-mask everywhere the second color won't go, etc. If you have a lot of lines in your paint scheme, as I do, there will be a lot to mask. And a lot of chances for paint to creep under the mask. Although we used the best tape for sealing, 3M's fine brand of Fine Line Plastic tape, we still had trouble with paint creeping under the tape. And this, even though we used a Croix HVLP unit to spray. Although there wasn't a lot of pressure trying to blast paint under the tape, there is still capillary action trying to pull paint under the tape. Some of my paint lines are only 1/8" wide, so

went on dry. But we were comfortable using an airbrush, and it paints such a small pattern that even if you goof up, it won't show up. So that's what we did. The first photo shows the plane ready for its first color Cranberry Red. Here we've used the airbrush to not only seal all taped edges, but we've used it to get to hard to reach areas (like the NACA scoop) and all hard edges (like the edge of the wing root fairing) as well. The second photo shows the culmination of this technique. Here we used the airbrush to paint my N-number's outline - a quarter inch open area that had to be

The solution to this problem is to

first color won't go; paint the first color;

FLY OUR AWARD-WINNING AIRCRAFT.

ous coat and wouldn't flow it out if it

Dakota Hawk

• AWARD-WINNING DESIGNS

• PROVEN

H - 8 0 T i g e r Moth

• RUGGED • STABLE

Super Koala

• FACTORY SUPPORT AND SERVICE SECOND TO NONE

• AFFORDABLE FLYING

Pa/rote Bwft, £>3/