This compact project incorporates an electrostatic corona motor to convert high voltage (HV), direct current (DC) into rotary motion. Although operation of this tabletop carousel is very simple, assembly requires time and careful work.
A negative ion generator spins a rotor that drives a circular stage, which provides a platform for paper cutouts of horses. When ions are sprayed on rotor's surface, rotor is pushed away and carries surplus ions to the adjacent grounded electrode. The repulsive force moves the stage and horses around the carousel's central support pole.
Nylon hardware and plastic sheeting were essential project components because these materials insulated thousands of volts from the bathroom tissue roll that I used for the motor frame and carousel housing. I collected the construction materials from a kitchen recycling bin as well as from an online hardware retailer.
Note: Some dimensions are metric; others are in US units depending on where parts were sourced.
Caution: Always disconnect HV wiring before working on your carousel! Secondly, depending on the rating of your ion generator, the motor can generate ozone gas, so operate your carousel in a ventilated area.
Step 1: Parts & Tools
12 volt DC ionizer (output: 7 kV @ 7.5 uA)
12 volt DC adapter w/adj slide switch
Cardboard bathroom tissue roll (commercial size: 9 cm L x 8.5 cm ID)
Cardboard end cover from 3-ring binder (aka: book binder's board)
Card stock sheet from product packaging or index card
Cardboard or plastic spacers from roll of dog litter bags (6 cm L x 0.8 cm ID)
Cardboard roll from used tape dispenser (approximate OD equal to tissue roll)
Nylon acorn caps (6; #1/4-20)
Nylon machine screws w/nuts (5; #8-32 x 1 inch L)
Nylon flat washers (5/16 inch ID; various OD & thickness)
Nylon screw insulators (10; 1/4 inch L x 1/2 ID)
Nylon cable clamps (8; 1/4 inch ID)
Plastic sheet from binder cover or product packaging
Plastic drinking straw (1; 1/4 ID)
Stainless steel, round head machine screws (6; #1/4-20 x 1/2 inch)
Cyano-acrylate (CA) glue
HV hook up wire (use old extension cord or volt-ohm meter test leads)
Horse images (4; about 2 cm x 2.5 cm)
Spade connectors (6)
Hole punch (1/4 dia)
Measuring tape (metric/non-metric)
Power drill w/assorted bits
Sandpaper & sanding block (course & med)
Wire crimping tool & stripper
Step 2: Prep Tissue Roll; Make Stage & Platforms
You will need one of those large diameter rolls sold by bulk retail outlets. Remove any adhesive residue; sand ends if needed to remove dings and surface scratches. The roll serves as a container for rotor, revolving stage as well as the structural support platforms, P1 and P2.
Remove plastic covering from 3-ring binder. Cut two discs from the cardboard to make P1 and P2 with diameters equal to outside diameter of housing. Chuck both disks in electric drill and use a sanding block to smooth rough edges until disks fit inside housing with only slight resistance.
Cut another disk for the stage from thin cardboard or an index card. Diameter should be about 5 mm less than inside diameter of housing. Ream center holes of stage, P1 and P2 to accept nylon insulator shaft. Lightly sand disk surfaces until smooth. Push an insulator shaft firmly through center holes until flange rests on disk.
Step 3: HV Source
Step 4: Assemble Rotor
Cut 2.5 cm from the bottom of a medicine vial. Line inside of vial with an aluminum foil strip. Cut a disk from binder's board with diameter equal to outside diameter of vial and chuck in electric drill. Use sanding block to smooth rough edges until disk fits inside vial with only slight resistance. Drill a 1/4 inch center hole through disk and bottom of vial.
Assemble rotor bearings by inserting a screw insulator through hole in bottom of vial. Insert insulator (with stage attached) through hole in disk to secure stage to opposite end of vial.
Step 5: Assemble Stator & Ion Sprayers
It's a good idea to paint housing now; otherwise, you will need to dissemble everything to avoid getting paint on the hardware...been there, done that... (:<(
Construction Tip: Before spray painting, rub a thin layer of white glue into cardboard surfaces with your finger. Sand with fine paper when dry, then wipe surfaces with lint-free cloth for a smooth surface.
Construct stator or non-moving part of motor by marking inside of housing for locations of six, equidistant, steel machine screws 2 cm from top edge of tube. Use punch or drill to make screw holes. I organized the necessary hardware on a table for quick assembly. Ream, then sand holes to accept insulator shafts with flanges on inside of housing. Insert screws with heads inside housing. Place nylon spacers on outside of housing as needed so spade connectors contact metal screws. Lastly, cap screw with nylon acorn nut. Paint P2 if desired; insert through bottom end of housing.
The installation of eight, nylon cable clamps provide strain relief for hook up wires connecting machine screws and support for P2. More importantly, the upper and lower set of clamps will keep hot and ground wires separate to reduce chance of arcing. Begin by drilling five holes to accept #10-32 x 1 inch nylon screws equidistant between machine screws and 4.5 cm from top of housing. We will do the wiring in next step.
Note: P2 should be located below metal screw heads and resting directly on nylon screw nuts. Heads are located outside of housing.
Fold six strips cut from an aluminum take out container into L-shaped ion sprayers and punch a 1/4 inch hole at one end of each sprayer for a machine screw. Insert nylon flat washers under hot leads to reduce possibility of arc faults.
Step 6: Hardwire Hot & Ground Leads
Cut two equal lengths of black (ground) and red (hot) hook up wire. Working clockwise while looking at top of carousel, connect ground and then hot electrodes. Insert stripped end of black wire into spade connector at 12:00 o'clock position and crimp or solder. Place section of heat shrink over connection to insulate metal from cardboard. Run wire through a lower set of clamps then connect to electrode at 4:00 position. Use remaining black wire to connect electrode at 8:00 o'clock position, then crimp or solder and cover with heat shrink tubing.
Repeat procedure with red wire, connecting electrodes at 2:00, 6:00 and 10:00 o'clock positions and thread each wire through upper set of clamps before terminating run. Secure clamps to housing with #10-32 x 1 inch nylon screws. I inserted plastic spacers between upper and lower clamps to maintain distance between ground and hot leads.
Step 7: Assemble & Install Base
This step is easy. Use CA to glue a scrap acrylic disk over insulator hole in P1. Attach three scrap wood pieces to the bottom of P1 to make feet for the carousel base. Make a stop ring to keep P1 level by cutting a empty cardboard tape roll so it can expand to fit inside housing. Secure with white glue. Use metal clips to hold ring in place until glue dries.
Step 8: Painting the Carousel
Here's a view of the finished base. After deciding to paint the housing, I had to disassemble the entire project up to this point (:> 0)
Step 9: Install Sprayers; Insert Support Pole & Rotor
Remove machine screws to install sprayers; they should face in same direction to reduce chance of arc faults. Separate stage from rotor then insert straw through bearings and through P2 until end of straw is firmly seated inside the insulator of P1. Hand spin rotor; it should turn easily.
Construction Tip: Bend sprayers for minimum clearance from rotor -- the smaller the distance, the greater the torque. This step is crucial because rotor must turn stage and horses. BTW, the initial project design used an electrostatic contact rotor (two end photos) that was scraped because of insufficient torque.
Step 10: Test Run #1
Bummer...the motor failed miserably when I connected the ionizer. Metallic spray paint used on the outside of housing got inside causing noisy arc faults between screw heads and the surrounding cardboard. Back for another deep dive in the recycling bin to find a solution.
I found some plastic sheets from fast food packaging, cut a strip to size and then used it to line inside of housing (P2 needed sanding to fit properly). I used metal clips to secure strip while marking and then drilling entry holes for insulators and metal screws.
Step 11: Test Run #2
Nailed It! Watch this bad boy spin without arcing.
Step 12: Glue Horses to Stage
I tried using these flying toy horses mounted on plastic coffee stir sticks as shown in initial photo, but they made the stage too heavy to turn. Paper cutouts are a better choice. Attach them to stage with a drop of white glue.
Construction Tips: Heavy paints can cause card stock to curl! Lightly spay paint stage, or use colored construction paper. Also, make sure horses are facing in the direction your stage turns; or you will need to roundup another herd. ( ; >)
Step 13: Add Carousel Roof
This plastic lid from a fast food, side dish container was the right size for the carousel's roof. Use CA to attach an insulator to the inside; place on rotor axle after trimming to appropriate height. Insert a pushpin on top of lid as a roof ornament.
Step 14: Install Secondary Roof Supports
Plastic, colored toothpicks worked well as supports for the roof. I slipped three of them, equally spaced, between housing and the plastic liner installed earlier.
Step 15: Attach Stage & Roof
Place roof on center pole. Trim one or more toothpicks if needed to keep roof level. In the 3rd photo, I swapped the original center pole straw for a silver-colored one. I modified the roof ornament by wrapping it with a piece of colored tape trimmed to look like a flag.
Step 16: Ramp Up the Voltage & Watch Those Horses Run!
Connect ionizer leads to a hot (red) and a ground (black) terminal of carousel with clips and hookup wire. Power up ionizer with AC adapter and stage should turn. You may need to prod one of the horses with a "chicken stick" (an Old School term for a piece of scrap wood used to spin model airplane props and avoid finger cuts) to reduce risk of electric shock. Also, dial back the adapter's output if you hear the sound of arc faults between sprayers. BTW, It was difficult to get the carousel to work in humid, outdoor weather. The cardboard components may have absorbed moisture causing current leakage that reduced the corona motor's efficiency. However, no problems when I tested the project indoors in an air conditioned room!
Here's a link to a YouTube video featuring the intro from the Broadway revival of Carousel to play when you display your project. (:>D)