Bill of Materials: Spinning top brushless DC motor PART NO

Transcription

1 Spinning top brushless DC motor PART NO The heart of this kit consists of a bifilar wound coil driven with two NPN transistors. While the circuit is easy, the coil will be tedious to wind since each wire is about 200 to 250 feet long. Neatness will help keep the size of the coil down. All parts are available through Jameco except the mirror, spindle and magnet. The options for the base will also have to be considered. Various materials can be used including wood and plexiglass. It is important to keep the battery away from the magnet at least 5 inches. The base can also serve as the bobbin for the coil keeping the parts count low. The addition of a single small rectifier diode will allow for connecting an optional small solar panel to the unit. Installing a rechargeable battery will keep the top going indefinitely. Time Required: 4 to 6 hours. depending on experience Experience Level: Intermediate Required tools and parts: Soldering iron. Wire cutters. Wire strippers. Screw drivers. Sand paper. Bill of Materials: Qty Jameco SKU Component Name N3904 NPN transistor Any small signal or general NPN transistor will work as long as the leads match the pattern on the PCB K resistor Î resistor Current limiting resistor for LED's Red LED Any color will do, the brighter the better. These LED's make the plexiglas base glow. The intensity will vary with the movement of the magnet ga. magnet wire This wire will need to be cut in half for the coil. Each half will need to be on its own bobbin for easier winding Battery holder A pc mount battery holder would also work and make assembly a little easier. 1 Mirror These mirrors are available in most department stores and range in price from $3 to $15. I recommend X10 magnification. X5 will also work however the top will be less energetic but also quieter. 1 Double pointed #3 knitting needles A package of four needles will make spindles for 8 tops. The end of the needle is cut to a length of 1 3/4 inches. 1 1" diametrically magnetized ring magnet. This magnet will fit nicely on the #3 knitting needle. A couple gentle taps will fit the magnet to the the needle. The needle is similar to a morris tapered shaft. 1 Base 3 1/2" X 5" Base (1/4" plexiglass)

2 This part has to be fabricated at a shop that works with plexiglas. 1 Miscellaneous Screws / Hardware The Jameco battery holder has one screw hole in the center a 1/2" 4-40 flathead screw will hold it to the base. 5/8" rubber feet can be added for support and to keep the screw from scratching wooden surfaces Solder-less Breadboard Using this part eliminates the need for soldering and allows easy component swapping for experimenting purposes. Step 1 - Inventory Parts. Open the kit and compare the parts list to the actual parts in the kit. You may receive extra components for some items. Step 2 - Familiarize yourself with the base plate There are six holes in the base plate (see photo). Two holes to attach the circuit board (this board is the solderable version for permanent construction Jameco Part# ). The solder less board provided in the kit will be secured with a rubber band. One hole to attach the battery holder. Two holes to guide the wire from the coil. One hole for the LED's. Step 3 - Attach the cable ties Tape two cable ties (one to the top of the base and one to the bottom of the base) as shown in the photo. The sides with the locking ridges should be facing out away from the base. Step 4 - Start the coil Hold the base with the top side facing away from you (the base is reversible so either side can be the top). Feed both wires through either one of the guide holes (your choice) leaving the other hole empty. Feed enough wire through to reach the end of the base where the battery holder will be and tape them down (see photo).

3 Step 5 - Wind the coil NOTE: It is highly recommended that you make a simple spool holder out of a cardboard box and piece of stiff wire to complete this step (see reference 1 photo). Begin winding the wires toward the opposite (farthest) notch, this will give needed slack later. Keep all the turns in the notches. Wind the layers as neat as possible however perfection is not necessary. It will take about 1 to 2 hours to wind the coil by hand so be patient. It is best to wind the coil by flipping the base over and over while holding the wire stationary. If you wrap the wire around the base while holding the base stationary, it will twist up on itself eventually causing kinks and difficulty winding. When you reach the end of the wires or fill the notches (which ever comes first) feed the ends through the remaining guide hole and tape them to the base as you did at the beginning (see photo). Make sure they are long enough to reach the end of the base where the battery holder will be. Cinch the cable ties around the wires to help hold them in place. When we reach the step where the wires are attached to the circuit board, two of the wires will cross sides. Step 6 - The winding process You will notice that some of the windings will appear loose on the front and back sides of the coil. There is no cause for concern as the cable ties will pull the windings together.

4 Step 7 - Complete the coil The coil is completed when either you run out of wire or the notches are full. Do not exceed the capacity of the notches. Cut the wires long enough to reach the end of the base where the battery holder will go. Feed them through the open guide hole and tape them to the base. Step 8 - Sand the wires Now that the coil is wound it is a good idea to remove the insulation from the wires. You will need a small piece of sand paper 150 grit or finer. Pinch a wire between the thumb and index finger. Fold the sand paper over the wire with the other hand and pull. Repeat this about ten times until the wire is shiny. Make sure to move the sand paper around the wire a little each time to get all the enamel. Repeat this for the other three wires.

5 Step 9 - Center tap Position the base with the coil away from you. Set the multimeter to low ohms scale. Attach one lead of the multimeter one of the wires on the left side of the coil and the other lead to one of the wires on the right side of the coil. If there is no reading move the lead to the other wire. You should get a reading of about 25 ohms. Leave the meter connected to those wires and pull the other two wires that are not connected to the meter back through the guide holes. Route the wire that was on the right through the left guide hole and the wire that was on the left through the right guide hole. Disconnect the meter and twist the two wires on the right side of the base together, they will be the center tap. Attach one probe of the meter to the center tap and the other to one of the two wires on the left. The reading should be about 25 ohms. Now test the other wire on the left. It also should read about 25 ohms. Step 10 - Mount The Breadboard This is a good time to get these components ready. There should be: 2 transistors. 4 resistors: two 2.2Kohm and two 150ohm. 2 LED's. 1 Breadboard.

6 Step 11 - Breadboard assembly 1 Place two wires in the position shown. Note: the board in the picture is longer than the one in the actual kit. Once the board is centered the two wires should line up on the sides of the large hole in the base (See diagram 3). There should be five empty holes between the two wires. Step 12 - Transistors Place the board in front of you with the coil facing away from you. Place the transistors on the board as shown with the flat side facing away from you (See diagram 3 for exact hole count). The collector will be the lead on the left in this configuration. Make sure the collector goes in the same row of holes as the jumper wire. Once both transistors are in place, run a wire from the emitter of Q1 to the emitter of Q2. The emitters are the right leads in this configuration.

7 Step 13 - Add the first bias resistor Orient the board with the coil facing you. Place one lead of the first bias resistor (2.2Kohm Red, Red, Red) into the collector of one of the transistors. The other lead will go to the base of the other transistor (See diagram 3). Step 14 - Add the second bias resistor The second bias resistor will connect between the transistor with nothing connected to its base and the opposite transistor with nothing connected to its collector except the jumper wire (See diagram 3).

8 Step 15 - Attach the coil wires. Attach one of the individual coil wires to the collector of Q1. Attach the other individual coil wire to the collector of Q2. It does not matter which wire goes to which collector. The center tap wire will connect shortly. See diagram 3 for reference. Step 16 - Add the LED resistors. Turn the base so the coil is facing away from you. You will be working on the half of the board that has been bridged by the two wires from each collector. Connect R3 from the collector of Q1 (on the left) to the hole just before the jumper from the collector of Q2 (on the right). Connect R4 from the collector of Q2 (on the right) to the hole just before the collector of Q1 (on the left). Refer to the diagram to see this in detail.

9 Step 17 - Prepare to install the LED's Study the photo and notice that the cathodes (short leads) of the LED's are closest to each other while the anodes (long leads) are farthest apart. This is how the LED's will be mounted to the board. See diagram 3 (the LED's cathodes and anodes are labeled). Step 18 - Bend the leads The leads of the LED's must be curled to 270 degrees so they will drop into the large hole and be facing forward (toward the coil). See photo for this step and next step.

10 Step 19 - LED final adjustment Align the LED's as seen in the photo so they shine through the thickness of the plexiglass (This causes the plexiglass base to give off a nice red glow. If the LED's are to low you will loose the effect). Step 20 - Connect the center tap Connect the center tap of the coil to the right side of the board (see diagram 3). The positive battery lead of the battery holder will also connect to this row of holes. I used the back half of the board for the power connections. The center tap wire makes for a good power switch. When you want to turn the motor off simply move it to an unused row of holes.

11 Step 21 - Attach the negative connection Using diagram 3 as a reference, position the board with the coil away from you and run a wire from the emitter of Q1 to the left edge / back half of the board as shown. Attach the negative lead of the battery holder to the same row. Step 22 - Mount the battery holder Use the 4-40 flat head screw to mount the battery. Position the battery holder over the small hole at the back of the board and push the screw through it. The nut will go underneath the base. Tighten the nut till it is snug. You may also want to shorten the leads from the battery holder so there is not so much slack.

12 Step 23 - Test the unit. Install the battery. Make sure the center tap of the coil is in the same row of holes as the positive wire and the negative wire is connected to the two emitters. The LED's should both light. Set the unit on a flat surface. Place the mirror in front of the coil. Set the top on the mirror and give it a spin. You should hear the top pick up speed. After a minute or two the top will set up an orbit around the mirror in the opposite direction it is spinning. If you spun the top clockwise it will orbit counter clockwise. Step 24 - Troubleshooting - No power 1. Center tap is connected but there are no lights: A. Verify the battery is good and installed correctly (tip facing the red wire). B. Verify the negative is connected to the emitters. C. Remember there is no connection between the two halves of the board. A jumper wire is necessary to bridge the two rows of holes. Step 25 - Troubleshooting - Lights are on but top won't spin. Lights are on but the top won't spin. A. Check the battery voltage. While the top can continue spinning when the voltage is lower than.6 volts (six tenths) the top will be reluctant to start from voltage that low. It is best to start it with at least 1 volt. A trick to try is to spin the top then gently lean the mirror to force the top closer to the coil. You should see or hear it pick up speed. B. The top is sensitive to any kind of metal by it or UNDER it. Many times there are bolts or brackets underneath the table that will prevent the top from spinning if it is to close to them. Move the motor over a few inches and try again. Look under the table and check for metal. NOTE aluminum, brass and copper with cause interference just the same as iron or steel.

13 Step 26 - Troubleshooting - Spiral of death When the top orbits it should maintain a vertical posture. When the top is spun at the start it may be leaning and not able to correct itself. This posture will worsen until it hits the mirror and skids to a stop. The solution is simple, place your finger or a non metallic rod in a place where the top will bump it as it makes an orbit. The top will righten itself on contact regardless of the the angle it is leaning when contact occurs. Step 27 - Going further Things to try: 1. Place a marble on the mirror and watch the top and marble battle. 2. Hold non magnetic metal near the spinning top (coin or aluminum can or copper pipe). What happens? 3. Take a small piece of paper and hold it on the mirror. See if you can get the top on the paper. try to pick the paper up while the top is on it (use both hands). See if you can transfer the top to a different mirror while it is still spinning and then move the motor assembly over to that mirrior to keep it spinning.. 4. Tie a thread onto a non-magnetic metal ring. Hold the ring by the thread and bring it near the spinning top. Is there any effect? 5. Try different size tops. You can also make tops from disk or block magnets. The circuit can spin a variety of permanent magnet motor armatures. Step 28 - Project Improvements Put 5/8" adhesive rubber feet onto the bottom of the base to raise it up level and prevent scratching. Following the same layout, reconstruct the circuit onto solderable breadboard for a more permanent installation. This is a good time to add a power switch. Add a solar panel, reverse polarity diode and battery. Step 29 - A word of CAUTION The top is a magnet and if it inadvertently gets close to magnetic metal or other magnets it can slam into them causing chipping and breaking. Small fragments can also cause injury. Keep the top away from other magnets and magnetic surfaces. NOTE: when the battery is new the top can gain enough momentum to jump off the mirror and roam freely. I have spent much time looking for the top on the floor only to find it stuck to the back of a speaker or some other metallic object. When enjoying your top always remain MAGNET AWARE. Step 30 - Diagram 1 - Base Plate Specs. Reference this diagram for details on constructing the base plate. NOTE: the two 3/64" holes closest to the notches are the guide holes for the coil wires. The two 7/64" holes directly below those are the mounting holes for the permanent board (Jameco part # ) and are not used with the solder-less breadboard included in the kit. Step 31 - Diagram 2 - Schematic Reference only.

14 I like to call this circuit a "Dual Thief" because it is essentially two joule thief circuits cross wired in a multivibrator configuration. Instead of using a small coil of a few turns to induce oscillations this circuit uses a large electromagnet to create a magnetic field strong enough to spin a permanent magnet. NOTE diode D3 is optional and not shown on the pictorial diagram. If some one wants to add a solar panel and a rechargeable battery the schematic shows where that diode would go. Step 32 - Diagram 3 - Pictorial Shown looking from the top. Step 33 - Reference 1 Using a stiff wire (coat hanger or 12 ga. copper) punch a hole in the side of the box about 1/2" down from the top. Push the wire to the opposite side and punch another hole. Try to keep the holes straight across from each other. Pull the wire out and punch another hole in the end of the box (this is the hole the wires will feed through). Put the wire back into one of the holes in the side and slide the wire spools on it. Push it the rest of the way through and secure it with tape if necessary. Feed the wires through the end hole. This simple device will save a lot of work and misery.

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