USB-Powered Apple

Well, the holiday season is quickly encroaching upon our otherwise uneventful and pleasant existences. Soon most of us will have to sit through many long meals with our family (or someone else's) and try to keep our sanity. I don't know about you, but during this time of year I could use some stress relief.

To keep with spirit of the season I made this USB-Powered Apple. It is really quite a simple device. It vibrates when a person grabs for it and does not vibrate when a person does not. Unlike your family, this apple is predictable and may relieve stress.

Go Get Stuff

parts:

1 - Apple (real or otherwise)
1 - Vibrating motor (preferably 1" diameter)
1 - 1+1/4" diameter PVC pipe (or to fit your motor)
1 - Water bottle cap (should your motor not fit snug inside the pipe)
1 - Copper foil (the thinnest sheet of copper you can find)
1 - USB cable
1 - QT113H capacitance sensor chip (obsolete)
1 - 8 pin socket (optional)
1 - 0.047uF polyester film capacitor
1 - 2N2222 transistor
1 - 1N4004 diode
1 - PCB project board
1 - 5" shielded wire
1 - red and black 22 AWG wire
1 - Electrical tape

tools:

- Soldering iron
- Xacto knife
- Multitool
- Hot glue gun
- Drill or awl
- Long nose pliers

Please note that some of the links on this page contain Amazon affiliate links. This does not change the price of any of the items for sale. However, I earn a small commission if you click on any of those links and buy anything. I reinvest this money into materials and tools for future projects.

Carve a Lid in the Bottom.

Carve a lid in the bottom of the apple as though you were carving a pumpkin. In other words, cut with the point of the blade pointing into the center of the apple so that when you hollow it out the lid won't fall back through.

The lid should be slightly wider than the PVC pipe that you want to encase your motor inside of.

Hollow Out the Apple.

Whether your apple is real or fake, you are going to want to carefully carve out a cylindrical hole. You should try to go deep enough so that the motor can drop in with at least an inch to spare. For this you may want to use a blade that is a little stronger than your exacto knife (such as a pocket knife).

Prepare the Plug.

Take your USB plug and cut off the end that will not easily plug into your computer. It should look like the picture below. The red and black wires are the ones that you will be concerned with later. Red is +5V and black is ground.

Once your wire is cut, make a hole in the side of the apple towards the base as thick as the wire. This hole should bore through until it hits the cylindrical hole you have already carved out. You can do this very carefully with a drill or an awl. Once the hole is complete, pass the wire through.

Build the Circuit.

Cut your PCB to be small enough to fit into the opening, but large enough accomodate the circuit (see secondary picture below).

Once the board is prepared, construct on it the circuit shown below. Note that the copper electrode should be connected to the circuit with shielded wire. The shielding should be connected to ground on the circuit, but not by any means touch the electrode.

Construct the Motor Casing.

If your motor does not fit snuggly inside the PVC pipe then see if a water bottle cap can. If it can, then cut a hole in it so that your motor fits snuggly inside the water bottle cap and then shove that inside the pipe. Once it is established that the motor is protected and that the weight can spin around without hitting the walls of the case, using your hot glue gun, glue everything into place.

Now that the motor casing is built, it's time to wrap your electrode (copper sheet) around the outside. Solder and/or glue the electrode into place.

Stuff the Apple.

Insulate the circuit board and any exposed wires with electrical tape. Carefully shove everything inside. Ideally you should put in the vibrating motor first and the circuit second so that the electrode is closer to the surface of the apple.

Should you want to increase the sensitivity of your apple, you can strip small sections of wire and pass them through the apple so that they are situated right below the skin's surface. Make sure that enough of the wire is sticking out within the cylinder so that when you pass the motor in, these wires will make contact with the electrode (but not so long that they will get caught in the spinning motor itself).

Testing Testing... 1 2 3...

Flip the apple right side up. Make sure the apple is not coming into contact with any strong electrical fields such as you or a cell phone.

Plug it in.

Nothing should happen.

Now put your hand around it.

It should vibrate.

however...

If you plug it in and it starts to vibrate and never stops then you can have one of many problems:
1. Your wiring is wrong.
2. Somewhere on the circuit wires are being crossed.
3. Ground wires are making contact with your electrode.
4. You have not used shielded cable for your electrode.
5. You have wired your shielded cable wrong.

If you plug it and nothing happens and then when you touch it nothing still happens:
1. Your wiring is wrong.
2. Somewhere on the circuit wires are being crossed.
3. Your chip or transistor may be dead.
4. Your USB cable is busted.

If you plug it in and it vibrates for 10 seconds every time you touch it then you probably are not using shielded electrode wire. The sensor is timing out and recallibrating itself every time it is triggered. Use shielded cable or fix your wiring.

Close It Up.

Once you are sure that it works, close the apple up. Take the lid and position it into place. With your hot glue gun, glue it shut however you see fit. Make sure it really works well before you do this.

Relax.

Plug it in and grab for it every time your relatives call.

Bzzzzzzz......ahhhhhhhhhh...... I make dinner this year? Sure.... fine..... ahhhhh.........

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