The Spotlight

Dating back to the mid-1800s, theatrical lighting played an important role in the entertainment industry [1]. As time progressed, the concept of spotlights continued to grow and became more commonly used. The goal of this project is to construct a small scale spotlight that can be used anywhere conveniently. It can be used for personal productions, YouTube video filming, etc.

What you will need:

1 Cardboard Tube (3x24") Here

2 Cardboard Sheets (8"x6"x6") Here

1 Roll of Duct Tape Here

1 Hot Glue Gun Here

1 Hot Glue Sticks Refill (x18) Here

2 DC motors Here

1 Pack (10) of Wooden Dowel Rods (0.5"x12") Here

1 Roll of reflective tape/paper Here

1 Spool of silicone covered jumper wire Here

1 Arduino Mega 2560 with USB Here

1 Breadboard Here

1 L293D H-Bridge Here

6 LEDs Here

1 10k-ohm Potentiometer Here

1 set of jumper wires (x30) Here

1 TITAN 200-lb 3-Wheel Brown Plastic Dolly Here

1 roll of solder Here

1 roll of electrical tape Here

1 16.9 oz water bottle Here

Tools for Construction:

Hand Drill

Box knife

Soldering gun

Handsaw

On the breadboard, follow the picture above. You will need the L293D, a potentiometer, the ATmega 2560 and jumper wires. Refer to this diagram throughout the project to ensure proper installation of LEDs and motors.

You will then need to solder 6 LEDs in parallel.

First, take about a foot jumper wire from the spool. You will then need to strip about 3-inches of the silicone off the wire on one end and about 1-inch stripped off the other end, this can be done using the stripping tool that comes with the spool. This will be done twice. On one of wires, using the wire with 3-inches of silicone removed, you will solder the anode (positive, long side) of the LED only to it. To properly solder see instructions below. On the other wire, also on the 3-inches removed silicone side, you will solder the cathode (negative, short side) of the LED only to it. Repeat those two steps for all 6 LEDs.

The wire that has the anodes on it, the 1-inch side will then be connected to the signal (middle) pin of the potentiometer on the breadboard and the cathode wire to ground pin of the potentiometer (right). The power pin of the potentiometer of the potentiometer will go to power (left). As seen in Step 1's schematic.

Similarly for the DC motors, strip 1-inch of the silicone on each side of the wire. Each motor will need 2 wires, for a total of 4 wires. Take one wire and solder it to the back of the DC motor, as seen above. Then take another wire and solder it to the other side of the motor. Do this for both motors. The sides not soldered will then be connected to the breadboard as seen in Step 1.

How to properly solder: https://www.makerspaces.com/how-to-solder/ [2]

To ensure that the anode and the cathodes of the LEDs to not touch, wrap the anode wire on the 3-inch side with electrical tape; as seen in picture.

Using a box cutter, determine what length to cut your cardboard tube. The included design utilized a 6 inch length to cut down on weight and still hold necessary components. Depending on your desires, you may want to extend the tube to hold a power supply, act as a counterweight for the motors, or just for visual aesthetics! If you are not sure what length you would like, you may return to this step at the end of the build.

Using a hand drill, or drill press, drill a hole just large enough to insert one of the dowel rods through the diameter of the cardboard tube as shown. It is recommended to use a 1/2" drill bit for this step. Once the dowel rod is inserted, verify there is an equal amount of dowel rod extending from both sides of the cardboard tube. If satisfied, use the hot glue gun to fix the dowel rod in place by gluing on the inside and outside of the tube.

If you do not own a hand drill or drill press, this step can be done using a box cutter. Take additional care to line the holes up before making any cuts!

Take the 16.9 oz bottle and remove the top portion of the bottle starting just below the angled section. This can easily be accomplished with a box cutter or pair of scissors. Try to keep the cut as straight as possible while following the bottle's diameter. Taking the top portion that was just cut, add reflective tape to both sides of the bottle. This works best if multiple pieces of reflective tape are cut and added to the bottle 1 by 1.

Using the inner diameter of the cardboard tube, cut a piece of cardboard to use as a mounting plate for the piece of the water bottle. Next, cut a concentric circle approximately the diameter of the water bottle in the mounting plate. Insert the water bottle piece into the mounting plate, and fix with glue.

Take the mounting plate from the previous step and insert it into the cardboard tube. The closer the bottle is to the opening of the tube, the further the light will extend out. It is best to mimic the picture above.

Now that the light fixture is built, it is ready to house the lights wired in step 2. Feed the lights into the fixture starting with the leading wires. The LEDs will not fit through the threaded end of the bottle, so it is best that the wires are fed through the larger diameter of the bottle.

Using the cardboard sheets, cut a tray with the boxcutters approximately 8" x 6" x 1" in size. The sides can be held together using duct tape. It should look like the picture above.

Using the remaining cardboard sheets, cut 4 plates the size of the inner footprint of the tray from the previous step.

In each of the 4 plates, cut a 1 inch by 1 inch square in the center. This is to create a cavity for the motor to sit in once the spotlight is fully assembled.

Shorten a dowel rod to about 4 inches long using a handsaw. Next, feed the dowel rod through the center of the TITAN 200-lb 3-Wheel Brown Plastic Dolly. Fix the dowel rod in place with hot glue on the top and bottom of the plastic dolly.

Using the hand drill, use a 5/64th inch drill bit to drill a small hole in the center of the dowel pin on the underside of the dolly. A 1/16th inch drill bit can also be used for a tighter fit. Once the hole is drilled, fill the hole with hot glue. Insert the axel of one of the DC motors into the glue filled hole and let harden. It is important that the hot glue does not ride too far up the axel. This could cause the motor to lose the ability to rotate.

Making sure the wires are attached to the motor, situate the dolly in the 8" x 6" x 1" tray with the motor sitting in the cavity formed by the 4 stacked plates. To avoid wires interfering with rotation, feed the wires under the 4 plates and out one of the 4 corners of the tray.

Attach 2 dowel rods vertically to the dolly as shown in the picture above using the hot glue gun. The dowel rods may be resistant to stick to the pads of the dolly. To increase the strength of the glue, the foam pads can be removed from the surface, and the rubber covering can be cut back to expose bare metal. The dowel rods can then be glued to the metal surface.

Recall the dowel rod inserted into the cardboard tube in step 5. This dowel rod will act as the spotlight's axel for rotation in the x axis. For proper mounting, the dowel rod must be resized. Using the vertical dowels attached in the precious step, measure the distance from center to center of the two dowel rods. Approximately 5 inches. This length is the same length the dowel rod in the cardboard tube should be cut to, while maintaining equal length of dowel rod extending from either side of the tube.

Take the cardboard tube dowel rod and drill a hole using either a 1/16th or 5/64th inch bit into the center of one end of the dowel. Then repeat the process of filling the hole with hot glue and inserting the motor axel. Remember to take caution that the glue does not ride too far up the axel and restrict rotation.

Attach the motor to one of the vertical dowel rods on the dolly using hot glue as shown in the picture.

Cut 2 small pieces of cardboard roughly 1 inch x 2 inch in size and attach them to the opposite vertical dowel rod with hot glue, leaving at least a 0.5 inch overhang above the end of the dowel rod. This will create a channel for the dowel rod to sit in for rotation. It stops the dowel rod from slipping during movement.

Depending on the weight of the light fixture, you may desire to add strength to the structure. This can be done easily by cutting 2, 5 inch x 1 inch strips and gluing them between the vertical dowel rods for support.

Then on your computer, you will need to download the Arduino IDE from the Arduino website. https://www.arduino.cc/en/software

Once that is installed, go ahead and plug in your ATmega2560 using the USB wire into your computer. Then in the Arduino IDE, under Tools, select ATmega2560 for your "Board:" options and AVR ISP for your "Programmer:" option. This will ensure that the IDE is reading from the correct board. After you have pasted the code attached into the Arduino IDE, you can compile and upload the code using the check mark and the right-pointing arrow in the top left-hand corner. Your motors should then start spinning. The electrical wiring is shown the the schematic above in Step 1.

Code is attached.

Now that you have the final project. the project is ready for testing. You can test the connection of the LEDs by moving the potentiometer from one end to the other, dimming and brightening the lights. As seen in the video. The DC motors should also be spinning, moving the base and the tube holding the lights. For us, this did not work for our DC motors were not strong enough to withstand the weight of the Spotlight. However, in Step 24 we suggest motors that would work better that we didn't use due to timing and budget.

The DC motors used in the project did not produce optimal torque and did not support the weight of our spotlight very well. To avoid this issue, we suggest using: High Torque DC Motor 12V 3500RPM Permanent Magnet Motor High Speed CW/CCW (12V DC 3500RPM). Full disclosure: these are of greater cost than the DC motors used in this project.

[1]“Spotlight,” Encyclopaedia Britannica. [Online]. Available: https://www.britannica.com/technology/spotlight. [Accessed: 02-Oct-2021].

[2] “How to solder: A complete beginners guide,” Makerspaces.com, 31-Oct-2021. [Online]. Available: https://www.makerspaces.com/how-to-solder/. [Accessed: 15-Dec-2021].