 Figure 1 - Red-light box - front view - red-light gel screen with no transparency |
 Figure 2 - Red-light box - back view - transparency storage folder and flashlight insertion tube |
 Figure 3 - Transparency generic sample - Planet |
 Figure 4 - Removable mini-mag light source |
 Figure 5 - Transparency inserted in red-light box |
 Figure 6 - Transparency generic sample - Dark cloud |
This document presents construction plans for a light-tight box to display red-light signs at star parties. The signs are laser-printed transparencies. The box is designed to screw onto a standard camera tripod mount. Using such a sign, it is possible to set-up an informational sign in front of a telescope at a star party that displays the type of object currently in the telescope. The intent is to have several of these signs in a line of telescopes pointed at different types of objects. Using a handout describing the major celestial objects (e.g. - double stars, dark clouds, open clusters, globulars, planetary nebula, several types of galaxies), the public can browse a line of scopes for an orrey of objects.
Attention was given to making the red-light box light-tight for white light.
This red-light box will be of interest to intermediate amateur astronomers and to astronomy clubs.
The approximate total construction cost in 2006 was $67.25 U.S.D. However, about 1/2 that cost is for one box of transparency paper for a laser printer. To build the red-light box alone, including buying a $10 U.S.D. mini-mag flashlight, is about $35. With a pre-existing flashlight, the expense is about $25 U.S.D.
The brightness of the illuminated transparency is dim and best for dark adapted eyes. Because the illuminated transparcencies are dim, the red-light box is unlikely to raise objections from other scope owners at a star party. The image can be brightned by substituting a brighter LED flashlight or by omitting the internal diffusion baffle.
A simple alternative to this sign display box is to purchase a variable red-LED flashlight from Rigel Systems or Orion Telescopes for $20-$30. Place paper signs on a clipboard. Hang the clipboard either from your telescope tripod legs or from a separate camera tripod.
The materials lists is presented below. Construction details and plans are presented in two pdf documents:
Assembly time is approximately 45 minutes.
| Item | Qty | Brand-Source | Used for | Price U.S.D. 2006 |
|---|---|---|---|---|
| Main functional components | ||||
| Mailing Box 13 1/2" x 2" x 2" | 1 | United Parcel Service | Project container | 1.80 |
| Mini-mag Light | 1 | None | White-light source | 10.00 |
| Gel Sheet - Red Diffusion #120 | 1 sheet |
Roscolux #120 Red Diffusion Available from theatrical supply companies Typically comes in 2' x 3' sheets |
Converts diffuse white to red light | 5.50 |
| Automobile air cleaner wing washer-nut 1/4 inch 20 thread | 1 | ACE Hardware | Screw-in point for camera tripod mount | 0.80 |
| Letter-sized manila folder | 1 | Off-supply |
1/2 holds transparencies to front of box 1/2 holds stores transparencies on back of box |
0.00 |
| Transparency film for laser printers | 1 box | Universal Transparency Film by 3M, CG5000, 50/Pack | Make transparencies | 32.00 |
| Insert tube for light | ||||
| 1/2" PVC threaded pipe 1 to 1 1/2" long (5/8" O.D.) | 1 | Hardware store | Insert tube for mini-mag light | 0.80 |
| PVC 1/2" I.D. couplers - threaded | 2 | Hardware store ($1.20 each) | Insert tube for mini-mag light | 2.40 |
| Black rubber stopper 3/4 inch by 5/8 inch | 1 | ACE Hardware | Make insert tube light tight | 0.55 |
| Black neoprene ring 2 1/4 inch O.D. x 5/8 inch I.D. | 1 | ACE Hardware | Make insert tube light tight | 1.80 |
| Light seal and reflection | ||||
| White flat spray paint | 1 can | ACE Hardware | Paint inside of mailing box to increase relfection | 3.30 |
| Aluminum kitchen foil | 1 sq ft | Common household product | Diffuser reflector | 0.00 |
| White duct tape | 1 roll |
Ace White Duct Tape Ace 42911 1.88" x 5 yards |
Mount components and seal box inside with reflection | 3.30 |
| Black duct tape | 1 roll |
Ace Black Duct Tape Ace 42913 1.88" x 5 yards |
Light-tight seal outside of box | 3.30 |
| Other materials | ||||
| Adhesive picture hangers | 2 |
Anchor Adhesive Picture Hangers Pack of 5 Ace Hardware 50595 (Anchor 47904) |
Second mount point to hang sign on an observatory door | 1.70 |
| Total cost | 67.25 |
If MS PowerPoint is used to prepare transparencies, that program includes a toner saving feature that overrides printing black background slides.
To work-around this limitation, draft slides white on a black background. Print the slides black on a white background and onto white paper. Use a copier with a positive-to-negative reversal feature. Copy the paper slides on to the transparencies.
Another work-around is to save the PowerPoint slides to a jpg format. Then use a standard image print utility to print the jpg slide directly to the transparency. These lower level utilities usually do not have a toner saving program feature built-in.
The content of this website are distributed without charge in the hope that it will be useful, but without any warranty, including without any implied warranty of merchantability or fitness for a particular purpose, to the extent permitted by applicable law. The content of this website is distributed "as is" without warranty of any kind, either expressed or implied. The entire risk as to the quality and performance of the red-light box and data herein are with you, including any general, special, incidental or consequential damages arising out of the use of or inability to use this website.
Any original materials on this website to the extent that copyright is held by this author, including the handouts, are released to public domain. Astronomy clubs and educators are encouraged to freely replicate this site.
Prepared by: K. Fisher 5/2006 fisherka@csolutions.net