!!WARNING!! This is a very dangerous project due to high voltages, I'm not liable for damage to property, injury, or death.
The circuit for this project is designed for a 120 volt outlet.
How it Works:
First, you drop the ball onto one of the ramps. When it reaches the bottom, an IR emitter/detector "sees" that it is there and sends 5 volts to the base of a transistor, which in turn, trips a relay. When the relay trips it dumps energy from high voltage capacitors into a coil, which works like a coil gun, and shoots the ball back up to the first ramp. Then the process repeats.
Sometimes it triggers more than once because it doesn't have enough "umph" to get the ball all the way up the tube. More capacitors would fix this.
I made a rather lame attempt at making this look nicer, to see how skip to step 12.
Step 1: Parts/Tools List
1/2" thick pine
3/4" thick pine
Lots of magnet wire
(1) Metal ball
(1) Wire coat hanger
(1) Tube with an inner diameter slightly greater than that of your ball
(1) 1n4001 diode (or similar)
(1) 1n4004 diode (or similar)
(1) 2n2222 transistor
(1) 10 K ohm resistor
(1) 470 ohm resistor
(1) 2.3 K ohm resistor
(1) 7805 regulator
(1) 12v relay with one normally closed switch and one normally open switch, it should be rated to handle at least 250v
(4) High voltage (around 200v) electrolytic capacitors (such as those found in camera flashes and PC power supplies)
(1) 100w light bulb and holder
(1) Bridge rectifier
(1) 12v wall wart or power supply
(1) Outlet plug
Drill with drill bits
Table saw or router
Step 2: Mechanics: Step 1
First, cut out two pieces of wood from the 1/2" thick pine. One piece should be 6" long by 1" wide, and the other should be 8" long by 1" wide.
Step 3: Mechanics: Step 2
Then, using a table saw or router, cut a groove down the middle of both the pieces of wood you cut earlier. The groove should be just the right size so that your ball rides nicely in it without touching the bottom of the groove.
Step 4: Mechanics: Step 3
After that, drill holes in the 6" piece of wood ~1/4" from the top and 5/16" from the end on each side and both ends. Also, drill holes in the 8" piece of wood, except only on one end. These measurements may change based on how deep your groove is. The holes should be slightly smaller then the diameter of your coat hanger.
Step 5: Mechanics: Step 4
Now, take your coat hanger and make two hooks that look like Ls. These will hold the 8" piece of wood at an angle. The length of both of the shorter pieces of the L together should be about 1".
Step 6: Mechanics: Step 5
Now take your 3/4" pine and cut out a piece about 10" long by 3 1/2" wide. This will be your base piece. After that, drill two holes about the same size as your coat hanger on either side of where you want your 8" piece of wood to be. These holes should be 1 and 1/4" from the edge of your base (see picture 2).
Step 7: Mechanics: Step 6
Now you can put your base and 8" piece of wood together! (see first picture) Repeat basically the same process for the 6" piece so that it looks like picture 2.
Step 8: Electronics: Step 1
Now you need to wind a bunch of magnet wire. I was lucky enough to find a bunch someone had already wound. When you are done winding your wire, stick your tube into the middle of it. I used a sharpie marker body that I drilled out, you may need to put some duct tape around the tube so that your coil fits snugly over it (see first picture). After that, you need to cut out a bit of your tube so that your metal ball can easily "rest" in it (see second picture).
Step 9: Electronics: Step 2
Now for the fun part! As explained earlier, there is an IR emitter and detector placed on either side of the track so that when the ball passes between them the IR light is interrupted, and the detector switches the NPN transistor. You should solder up the circuit based on the following schematic. Before you do, I suggest you look where I put my components (next step), so that you know how long to make the wires. I housed the capacitors, rectifier, and light bulb in a separate disposable sandwich box. Also, you should take the QRD1114 apart so that the emitter and detector are separate, they should just slip out of the black housing. You may need to add more capacitors if your ball doesn't shoot up all the way.
Step 10: Placing Components
The tube should be placed in such a way so that when the ball is dropped, it will roll into the cut away part of the tube. The top part of the tube should be almost flush with the top ramp. The IR emitter/detector circuit should also be placed so that when the ball rolls into the tube, it will block the light going to the detector from the emitter. You may also need to move the coil up and down to achieve the right amount of magnetic force on the ball. If you don't understand, hopefully the pictures will clear it up for you. I secured the tube with a little hot glue and a zip tie.
Step 11: Finishing Touches
To make sure the ball goes down the ramp when it comes out of the tube, you need to make a guide. For right now I made mine out of duct tape. You might also need to put a back stop so that the ball doesn't go off the track when it drops down to the second ramp. I hope you had fun reading this! Tell me if you make one! If I forgot to explain something, please leave a comment.
Step 12: Upgrade: Step 1
3/16" pine plywood
1/8" x 1" pine
Cut five pieces out of the plywood as follows (see first image):
(2) 2 9/16" W x 5 3/16" H
(1) 3 1/2" W x 5 3/16" H
(1) 3 1/2" W x 4 7/16" H
(1) 3 1/2" L x 2 1/8" W
This upgrade is just a box that fits over all the ugly electronics. You should also be able to fit your capacitors, light bulb, and rectifier in it instead of them being in a separate container.
Step 13: Upgrade: Step 2
Now take the 3 1/2" W x 4 7/16" H piece of wood and cut a 1 inch wide slot down the middle of it, starting 1 inch from the top. Also, drill a hole in your 3 1/2" W x 5 3/16" H piece of plywood big enough so that your cords can fit through, the hole should be about 1 1/4" from the bottom.
Step 14: Upgrade: Step 3
Now glue all the pieces together (except for the 3 1/2" L x 2 1/8" W piece) using your favorite adhesive so that it looks like the picture.
Step 15: Upgrade: Step 4
With the 3 1/2" x 2 1/8" piece, cut out part of the corner so that it can fit around the light bulb. This is the top of your box.
Step 16: Upgrade: Step 5
We will now replace the tape back stop with 1/8" pine. Cut one 1 3/4" piece and one 2 1/8" piece and secure them using your favorite adhesive.
Step 17: Upgrade: Step 6
All you have to do now is place the box that you made over the coil, relay etc. and secure your rectifier, light bulb, and capacitors inside the box (I used a little hot glue). The top that you made just friction-fits on.
Second Prize in the
Kinetic Sculpture Design Contest