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How I Lit the Police Car

Note: I am not an electrician!  I'm am not a soldering professional!  My point?  You could probably do this too with good planning and patience.

This was my first attempt at using fiber optics and I've got to say that it's a lot easier than I thought.  The basic principle is that you have a light source, put one end of the fiber optic cable to the light, and the other end where you want the light to actually be.


The hard part: Hollowing out the police car and drilling the holes for the lights

What I Used:

  • 2 1.8mm red/blue flashing LEDs (fast)

  • 1 1.8mm red flashing LED (fast)

  • 1 1,8mm blue flashing LED (fast)

  • 8 feet .75mm fiber optic wire (for top lights)

  • 4 feet .5mm fiber optic wire (for rear lights)

  • Heat shrink tubing

  • #75 Micro Drill Bit

  • #68 micro drill bit

  • Soldering iron

  • Dremel


     The LED's were 3.25 each

     $0.12/foot for .75mm fiber optic

     $0.08/foot for .5mm fiber optic


Total Cost to Light:  $14.28

(Does not include tax or shipping costs)

Summarized general steps can be found at the bottom of this page

Possible Uses:

  • Lighting cars

  • Lighting houses

  • Lighting airport runways

  • Lighting coal mine workman's hats

  • You name it!

Click on the image to see how to use fiber optics to make a blinking arrow sign.


A brief warning:  Securing a fiber optic cable to a LED using CA (super) glue is not recommended.  As the glue cures it produces heat which makes the cable brittle and more likely to break.

The special challenge for this project was the fact that it's a briefcase layout which gets carried around and sits upright, on its side, and upside down.  I needed to find a way to keep a very thin fiber optic cable in front of the light.

Step 1)  Test all of the lights to be sure they work


Step 2) Find a way to secure thee fiber optic cable in front of the LEDs.

     I decided that I would cut some styrene strips to fit over the light and glue them in place.  I first tried cutting it with an X-Acto knife, but ended badly when the knife slipped and I almost ended up going to the emergency room for stitches in my finger.  I decided a Band-Aid would do and I almost have no pain remaining.  Bad choice.

     I regrouped and decided to use my Dremel (a small handheld drill with interchangeable bits).  I cut 4 3 inch pieces of styrene and used a small grinding bit to clear an opening in each one.  I checked the fit of the styrene piece over the LED constantly until each one could fit completely over the light.  Once I finished I cut the excess off so I was left with the piece that fit over the light and a little top part where the fiber optic cable would be fed through so it hit the LED directly in the center

Now I drilled holes using micro drills that were a tiny bit thicker than my fiber optics.  For the first two styrene pieces I used a #75 drill bit (.5334mm or .021in) and drilled one hole down the middle so I could slip the fiber optic wire for the rear flashers through it.  For the second two I used a #68 drill bit (.7874mm or .031in) and drilled 2 holes down the center of each so I could fit 2 .75mm strands in.  Each of the lights on the top of the police car will have 2 strands.  Once this was all done I tested to make sure I had drilled straight so the fiber optics would line up to the center of the LEDs.  Everything looked good so I used a little CA glue to attach the styrene to the sides of the LED.

Step 3)  Time to hollow out and drill holes in the police car.

     Using the #75 micro drill bit, I used my fingers to drill a hole straight into the car on each side of the trunk of the police car to the side of where the license plate would be located.  I only needed to drill in a little bit since I would be hollowing out the police car.  After using my X-Acto knife to remove the plastic light bar I then repeated the process with the #68 bit on the top of the car.  2 holes for each light.

As you can see, the car is one solid cast resin piece.  Now it was time for me to grab my Dremel again and hollow it out so I can get the fiber optics in for the rear and top of the car.  This is the time to be EXTREMELY careful and take your time.  Go too close to the edge and you can grind right through the side of the car.  Go too high and you'll come out the top.  By drilling the holes for the lights first, I now know how high and how far out I need to go.  I continued grinding away until I reached the holes from the roof and once I had cleared the holes for the trunk.

In this picture you can see just how much of the car I had to hollow out in order to get to the holes in the roof and through the trunk.  The Dremel slipped a couple of times, but thankfully no damage was done to the outside of the car.  After testing the fiber optic clearance and fitting, back to the wiring it is!


I wanted to disturb the wiring that's already on the layout as little as possible so I decided to set all of the LEDs up on their own assembly and then I'd just attach that to the existing wire.

Step 4) Solder the LED wires to the power source.

     Strip the ends of all the LED's wires.  Strip the main connection wires I'll be attaching them to for power.  Now it's time to solder all of the connections.


This picture shows what it looked like after the LEDs were connecting to their assembly.  Each LED has one wire connected to the red wire and their other connected to the blue wire.  When it comes time to add this to the layout, I only need to attach the red and blue wire. All of the LEDs will receive power once the red and blue are connected to the layout's current wiring.

Step 5) Angle and connect the fiber optics to the LEDs.

     I needed to bend the fiber optics for the trunk because they were going to come straight through the layout and up into the car.  The ones for the roof were fine.  They could come straight up and through, but the trunk holes are at a 90 degree angle.  After a lot of searching, I found something someone posted about using the heat from a soldering iron.  Hear up a soldering iron and hold the cable you want to bend horizontally over the larger part of the heating element.  Hold it close, but not too close.  If your iron is hot, then the cable will quickly and easily bend.  The best part is that it still transmits the light effectively.  Make sure you do any bending before securing them to the LEDs.  Just in case.

Step 6) Attach the fiber optics to the LEDs


     FIRST I slipped the fiber optic cable into the styrene and make sure it's touching the LED.  Now I add the caulk around where the cable goes into the styrene.  I didn't put caulk down first because then when the cable gets inserted into the hole it will have caulk on the end which will affect its ability to receive light.  It would still work, but not as well.  I used a toothpick to add on extra caulk and to try to coax it inside the hole.  Also, I decided to slip on some 2.5mm heat shrink tubing onto each of the sets of cables. I can then use my soldering iron to heat shrink the connection for added strength and to keep the light from shining underneath the layout. Lastly I put some caulk in the open ends of the heat shrink tubing as added protecting and to trap some of the light that could escape through the opening.

2 .75mm fiber optic cables for the blue flasher on the roof.

Single .5mm cable for the trunk  red/blue flasher.

Step 7) Make the hole in the layout for the fiber optic cables.

     Now it's time to make a hole in the layout so we can pass the fiber optics through it and up to the police car.  I made a small hole in the layout that would be covered by the police car and made the hole bigger as I went down so that the fiber optic cables would have a smoother transition towards the wiring.  To the right is a picture of the basic idea.  It would also make it easier to feed the cables through starting with a larger hole rather than trying to thread them through like you would a needle.

Step 8) Connect the assembly to the main power.

     Solder the LED assembly, complete with fiber optics to the existing wiring.  Once it was soldered I tested it to make sure that everything was working properly.

Step 9) Get the fiber optic cables in place

     Now to feed through the fiber optics.  I pass them from the bottom of the board through the hole and slide them into their holes in the police car.  I left about 3 inches sticking out of the soles in the police car that will be trimmed of after I glue them inside.  Before gluing, I painted the wires coming from the police car black so that you won't see light from under the police car.

Step 10) Secure the fiber optics in the police car.

     With the fiber optics in place I filled the inside with caulk and gave a healthy extra dose of caulk in addition so I could push it into place in the layout.  This basically combined 2 steps into 1.  Now when the caulk dries the fiber optics will be secure and the car will be secured to the layout.  I used a toothpick to remove any caulk that I didn't want to be seen.

Step 11) Secure the wires under the layout.

     With the caulk dry and the police car securely held in place, it's time for some wire/fiber optic management on the bottom of the layout.  With the layout upside down I coil and position the fiber optics and LEDs and use foam pins to hold them in place.  I then put a very healthy amount of caulk over everything and leave it to dry.  Once it's dry I'll remove the pins and the caulk will hold everything tight in place.

Warning: If you are into wire management then please use your own judgement before clicking on the pictures to view their full size.  It's not a pretty sight!

These two pictures show the fiber optic cables, LEDs, and the entire assembly covered in caulk.  There's no need to worry about the caulk melting because they don't produce heat.  The black squares you see are markers for me because there are supports inside the briefcase that keep the layout off of the bottom so that there's room for the wires.

Step 12) Enjoy your work.  All that's left now is to flip the layout right side up, apply power, and enjoy the lights!

Summarized Steps for Fiber Optics

  1. Buy LEDs with resistors or buy LEDs separately and solder on your own resistors

  2. Solder LEDs to power cables

  3. Attach LED underneath layout

  4. Drill hole through baseboard for fiber optics in your layout

  5. Pass fiber optics through the hole while leaving extra fiber optic cable in layout to trim later

  6. Attach fiber optics to or in front of LED

  7. Cover LED and fiber optic connection with light box or some way to cover the connection

  8. Trim excess fiber optic cable to make it flush with your layout

  9. Apply power and enjoy!

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