My attention was recently captured by an old movie, actually a Charlie Chan one, I just saw. It showed a spinning spiral disk that put people into a hypnotic trance. So, I decided to build one.

This disk is inexpensive, entertaining, fun to use, and extremely quick and easy to build.

It might even work to hypnotize folks.

Please let me know if you have had success.

Supplies

Electronic-based:

- Arduino UNO or clone

- Hookup cables, Dupont - 470 ohm 1 watt resistor

- A half-size breadboard

- Small DC Motor (I used an RF-300-12350 to allow easy disk attachment)

- ‘Experimental platform’ (I used an acrylic one, but any platform that can hold a breadboard & UNO will do)

- Heat shrink wire wrap (not really necessary as black electrician's tape will work as well) - 2N2222 transistor, or equivalent, to switch current

- 1N4001 diode

- Slide switch All these components are standard and available from a variety of sources, such as eBay. Most components are also available from Amazon. Craft-based:

- Glue gun

- Glue for gun

- A small wooden cross (I made mine from ¾”-wide pieces of balsa wood) ----- Cross is roughly 9” long x 9” wide ----- One arm is placed about 1/3 the way down the other, see photo

- An old/spare DVD - Colored spiral (see attached photo), with its rainbow of colors, reprinted with the kind permission of Dr. Akiyoshi Kitaoka, Professor of Psychology at the College of Letters, Ritsumeikan University, Kyoto, Japan. A picture of that spiral illustration is presented here so that it can be cut and pasted on a DVD.

- Rubber cement (but any glue that can be easily spread should work)

Step 1: Experimental Platform

The acrylic experimental platform that I used came covered with paper (to protect the clear acrylic) on both sides of the platform. Included in the package with the acrylic platform are five screws, five nuts, and five clear spacers, along with four relatively soft self-adhesive plastic feet.

If you use the same experimental platform I did: Peel the paper back on each side of the platform and remove it. Once the paper is removed the four holes for mounting the Arduino to the platform are easily seen. If you use a different platform the steps will be similar, although you may not need to remove any paper. Mount the Arduino on the platform you selected. I only needed to use four of the five screws, nuts, and clear spacers. That is, there was an extra screw, nut, and spacer included but not needed. The Arduino UNO R3 board has four mounting holes. The clear plastic spacers are placed between the underside of the Arduino UNO R3 and the upper side of the acrylic platform. The spacers are positioned around the screws that pass through the Arduino mounting holes and the holes in the experimental platform. The screws and nuts should be tightened to insure that the Arduino will not move in use.

The underside of the half-sized breadboard is covered with paper pressed onto an adhesive backing. Remove this paper and press the breadboard, with its now exposed adhesive backing, onto the experimental platform. It You should try to place one side of the breadboard parallel to the side of Arduino it is closest to.

Next, turn the platform over and mount the four included plastic feet on the four corners of the platform’s underside.

If you use a different platform the work required is likely to be similarly easy, but it may be different.

Whatever experimental platform you use, when you finish you should have both the Arduino UNO R3 and a half-size breadboard mounted on it, and four feet on the underside to allow the platform and breadboard to be placed on any flat surface without marring that surface, while providing firm support to the assembly.

Step 2: Soldering

Solder one end for each of two Dupont male-to-male wires to the two wires coming from the motor. I enclosed these two solder connections in heat shrink wire wrap, but black electrical tape should work just as well.

The motor uses about 68ma when spinning a DVD. That is more than the 40ma of current available from an Arduino pin. I used a 2N2222 transistor to handle the increased motor current. A 1N4001 diode was placed across the two pins of the motor, with the line on the diode facing the positive voltage. The 1N4001 was used as a flyback diode to offer a path for the reverse current flow caused by the collapsing magnetic field of the motor when the power is shutoff.

I used Arduino digital pin 5 to allow me to send PWM signals to the motor to reduce its speed. If I were to build this again, I might use another motor one with a slower speed, e.g., S30K 20rpm, as the duty cycle I found worked, but was almost at the point where the motor did not turn. That is, a further reduction in duty cycle, relative to that shown in the sketch below, would result in the DVD not spinning, at least for the copy of the RF-300-12350 motor I used. This DVD replacement motor has a ledge to hold a DVD, thereby making attachment easy. However, if done again, I would likely try a slower motor, such as the one mentioned above. However, that motor is on order and has not yet arrived. So, I have not had a chance to test it; so whether it will actually function better is just an opinion at this point. Fortunately, the motor used in this Instructable works, and without issue. However, if I needed to slow it even more, I could not.

Step 3: Electrical Hookup Without Motor

Hook up all the electric-based components, except the motor, on the breadboard. The hookup is quite simple, and can be easily seen in the picture. The photograph should be self-explanatory. However, it may help to know that the rightmost red and black Dupont wires of the red and black wire pairs go to the 3.3v and GND pins, respectively, of the Arduino. The other red and black wires of the pairs connect to the motor, and the yellow wire connects to digital pin 5 on the Arduino. The slide switch is inserted between the 3.3v pin of the Arduino and the red wire from the motor.

Step 4: Assembly

Place a DVD over the spiral and trace both the outside of the DVD on the spiral and the DVD’s inside circle. The inside can be traced many time with a pen until the inside paper on the spiral finally is severed from the rest of the spiral. Take the remaining portion of the spiral and cut the marked part out to get a paper cover that can be glued to the old DVD. I used rubber cement to do the gluing, but any relatively free flowing glue should do. I then took a glue gun and glued the experimental platform to the balsa wood cross, with the top of the platform aligned roughly with the top of the cross member, and then glued the rear of the motor to one of the extremities of the cross (see attached picture).

I used larger heat shrink wrap tubing to hold the red and black wires to the motor together. Fortunately, here again, black electrical tape should work as well, perhaps even better.

A picture of what the final ‘hypnotic’ disk should look like is shown in this the picture below.

Step 5: Afterwards

Now copy and paste the sketch below into the Arduino IDE. Connect the Arduino to your computer and download the sketch. The disk should start spinning. If all goes as hoped for, you are done.

* Sketch to spin a 'hypnotic' disk

* Written by R. Jordan Kreindler June 23, 2016

* Use 3.3v to the DVD spindle motor, a 1N4001 diode across the motor

* to handle reverse current when the motor is switched off, and a 470 ohm

* 1 watt resistor to limit current to the 2N2222 transistor's base pin

int dvdPin = 5;

void setup()

{

pinMode(dvdPin, OUTPUT);

}

void loop() {

analogWrite(dvdPin, 60);

}

Congratulations, you now have built a ‘hypnotic’ disk. Take some time to enjoy it.

Afterwards.
If you would like to contact me with any questions or for additional information, or to expand my knowledge about hypnotic disks, I can be reached at transiintbox@gmail.com. (please replace the second 'i' with an 'e' to contact me.