IT DOESN'T WORK? - - DEBUGGING!
If the light bulb won't light, usually it's because the wrong bulb was used. Follow instructions. If you changed the magnets, it won't work. So don't use different magnets. If you used a different bulb, it won't work. Use the parts in the partslist, don't make changes. If you're not using #30 enamel varnish-coated wire, then it won't work. So don't use different wire. Don't use different parts. Before testing anything else, ask yourself if you used the parts in the parts list. If you used different parts, the generator will fail. Notice: it's very important that you use the parts listed, and don't use substitutes. And have I mentioned, DON'T USE FREAKIN' DIFFERENT PARTS! What, do you WANT it to fail. )
SPIN IT FAST, IN THE DARK
Sometimes your generator is working fine, but you're not spinning it fast enough. Flick the nail between finger and thumb, like when you snap your fingers. or like when you spin a top at maximum speed. Make your magnets really whiz like a blur. (If they grind against the cardboard, it won't work.) Or perhaps the dim glow of the light bulb is being missed in a brightly lit room. So, go into semi-darkness. Then spin that thing REALLY FAST. Try cranking it with an old-fashioned hand-crank drill (electric drills don't go very fast). Or try sticking a little wheel on your nail, then rub the wheel on the spinning tire of an upside-down bicycle (don't go too fast or the bulb will burn out.)
ADD LOTS MORE WI RE
If your coil has more than 250 turns of #30 wire, then the magnet doesn't need to spin so fast. And the bulb lights brighter. The #30 spool of thin red Radio Shack wire is 200 feet long, which gives about 250 turns. If you could wind more turns on your coil, then your bulb would light up at lower magnet speed. Buy two kits of wi re from Radio Shack, then use both spools of the thinnest type (red #30.) Scrape the red plastic coating off all the wire ends. Then securely twist the end of the new spool to the end of the old one. Cover the joint with a bit of plastic tape, if you prefer. This creates a single longer wi re. Be sure to wind the extra wire in the same direction as before. Even better, buy a few "open frame solenoids" from mail order, or buy larger spools of wire. It's lots cheaper than Radio Shack.
If the wire is way thinner than #30 gauge, the resistance is too high and the bulb will be very dim. If the wire is too thick (or if it has thick insulation,) then 250 turns will be the size of a grapefruit, and the outer turns will be too far from the magnets. Better source of wi re: buy a large "Solenoid" from a mail order company, then use Vice-grip pliers to pry open the metal bracket. Remove the the big coil, peel off the tape, and wind it on your generator. Try this one:
12V solenoid $3.75
DON'T USE OTHER MAGNETS
Use the large 2-inch rectangular ceramic block magnets sold by Radio Shack and others #64-1899. Or try Others listed here. They cost about $2 each, and have no holes through the center. Don't use the smaller 1 inch Radio Shack magnets. Most other magnets are too weak and will not work unless you spin the magnets incredibly fast, at thousands of RPM (revolutions per minute.) Neo rare-earth supermagnets, of the same size as above, will work even better, but expensive.
USING SMALLER MAGNETS
If you can't wait for mail-order of the correct magnets, instead you can use twenty of the 1" magnets 64-1879. Glue them together to form two large magnets. Here's how I did it. First I formed four larger magnets: I glued twenty magnets in four separate stacks of five magnets each. I used 5-minute epoxy. Before the glue hardens, adjust the magnets so the sides of each small stack are flat, and wipe off the excess epoxy. (To make the sides flat, I laid each stack down on aluminum foil, pressed them down to align the magnets, then peeled off the foil when the glue was hard.) Next, glue two of these 5-magnet stacks together side by side so the stacks are repelling each other, then hold them together until the glue hardens. That way the N pole of one stack is near the N pole of the other, and S is near S. Do the same with the other two stacks. This gives you two large magnets, each made up of ten small ones. Each magnet should have two holes on each flat pole face. Let the magnets clamp themselves on either side of your nail as usual. These aren't as powerful as the four "high energy" ceramic magnets, so you'll need twice as much wi re for your generator.
DON'T USE A DIFFERENT BULB
This generator cannot power a normal flashlight bulb, it needs the special 25-milliamp, 1.5-volt bulb sold by Radio Shack. Also try using a red LED (but you must spin magnets much faster, like twenty turns per second. Or use way more turns of wire.) Don't use a normal flashlight bulb, since that kind of bulb requires way more energy before it starts to glow. If you simply cannot find the Radio Shack 25mA bulb, you can use a 1.5V 40mA bulb, but add twice as much magnet wi re to your coil (buy two of those kits of magnet wire.) The generator needs way more than 250 turns wrapped around it. Five hundred turns is better, that way you won't have to spin the magnets so fast. If you use a red LED, then use three times more turns of wire. The special light bulb needs one half volt, while Red LEDs light up at 1.7volts.
STACK THE MAGNETS SO THEY STRONGLY ATTRACT
Make sure the magnets are stacked to create two strong poles, otherwise the generator won't work. Do this: stack up all four magnets so their widest faces are clinging together. Then jam the nail through the crack in the middle of the stack. Then take this apart, and re-assemble it inside the generator in the same way.
CLEAN THE WI RE ENDS THOROUGHLY
If the generator refuses to work, inspect the spot where the wi res twist together. The generator coil has a very thin red plastic coating, and you must clean ALL of this coating off the wi re ends before twisting them to the light bulb wires. Also, the tips of the light bulb wires must be stripped clean of plastic. The metal wires must touch together. If there is plastic between the metal of the generator wire and the light bulb wire, the circuit will be "open" and no charge will flow.
Be sure to follow the instructions and diagrams. You MUST wind the coil so the coil goes across the side of the box which has the nail hole. If you wind it so no coil is crossing the nail-hole side of the box, then the magnetic fields won't cut across the wires, and no electric voltage will be created.
Also, don't wind the coil over the open end of the box, otherwise you won't be able to get your fingers inside to make changes to the magnet.
If you cannot spin the magnets fast enough with your fingers, try a "twist drill" or hand-crank drill. Clamp the nail in the end of the drill and spin the magnets as fast as you can. An electric drill may work too, but most electric drills don't move as fast as the hand-cranked type. Also try Arvind Gupta's trick: wind about 300cm of string around the nail, then pull it hard to spin the magnets fast.
[WARNING, SOME AC VOLTMETERS WON'T WORK AT 4 CYCLES PER SECOND, AND ARE DESIGNED ONLY TO MEASURE 50Hz or 60Hz.]
If you have a DMM voltmeter. set it to measure two volts AC, then connect it to the generator wires and spin the generator. The light bulb needs a bit more than 0.50 volts AC in order to light dimly. At 1.0V it lights brightly. If your generator's voltage is lower than 0.5V, you need to spin it much faster, or you need strong magnets, or you need to add lots more turns of wire.
DON'T SUBSTITUTE THE MAGNETS OR THE BULB WITH A DIFFERENT TYPE
It needs strong magnets and a low-voltage, low-current incandescent bulb. If your generator doesn't work, check the parts again and make sure you have the right type of magnets and the right type of light bulb. Don't use fewer magnets. Weaker magnets may work in theory, but you won't be able to spin them fast enough by hand, and a high speed motor will be required in order to spin them. Don't use an LED. A red LED could work in theory, but you need at least 1-1/2 volts to barely light one up (the green or blue kind need even higher volts.) The light bulb is better because it lights up at less than 1/2 volt. (If you really must light up an LED, use the red kind, and also add about three more spools of #30 wire to your generator coil.)
Perhaps your luck is bad and you got a dead light bulb. To test it, get any new, fresh 1.5V battery (the size doesn't matter.) Take the bulb off the generator, then touch one wire form the bulb to the top of the battery and one wire to the bottom. The light bulb should light up brightly. If it stays dark, the bulb is bad.
The generator can be improved by using more turns of wi re. You used only the spool of #30 wi re. With more wi re, the magnets don't have to spin as fast to light the bulb. Connect the thinnest of the remaining spools of wi re to one end of the wi re that's already wrapped, making sure to scrape the wi re ends totally clean before twisting them together. Make sure to wind the extra wi re in the same direction as the rest of the coil.
Or, if you want to light your light bulb REALLY bright, buy a second kit of wi re, hook the second #30 spool to the coil you have already made, then wind all the wi re onto the coil. Be sure to clean all the red plastic off the ends of the extra wi re that you've added.
FREQUENTLY-ASKED QUESTIONSMAGNETS: If you can't get those magnets from Radio Shack (Tandy), then call any big hardware store or hobby/craqfts store. Ask for large rectangle magnets, about 22mm by 46mm by 10mm. Or you can buy them from mail order companies such as these:
- Edu. Inv M-700
- R Shk #64-1877
- f4mag UK
- emag uk
- 50mm magnet spec sheet
WIRE: That wire from Radio Shack is $7 expensive,
especially if you buy two kits.
Much cheaper is to buy one or two open-frame DC solenoids from All Electronics or sometimes try Electronics Goldmine. Use Visegrip pliers to bend the frame apart, and take out the plastic spool of wire.
Zero cost wire? Old color CRTs and TV sets, the hoop-shaped "degaussing coil" around the outer edge of the CRT has long footage of magnet wire. Usually it looks like a black rope wound in plastic tape.
BULB: You can light up a common red LED, but only if you wind lots more wire onto the box. 200ft of wire will let you light up that special incandescent bulb from Radio Shack. Add 2X or 3X more wire if you want to flash a red LED. Green LEDs will work too, but they need even more volts than the red kind. Blue or white LEDs need far higher voltage than red or green, so first make it work using red LEDs. If you really want to use a light bulb, All Electronics sells a LP-3 bulb that works. Or find a 2-volt #48 bulb from many different suppliers. NORMAL FLASHLIGHT BULBS WON'T WORK.
2. CAN WE GREATLY INCREASE THE GENERATOR'S VOLTAGE?Increase the voltage? Sure. Just use a machine shop to carve some close-spaced iron parts. NOT! The Simple Generator is designed for kids to build, so it only puts out about half a volt. But here's how to increase the voltage and the maximum current by about ten times:
- Use two or four large rectangular supermagnets instead of large ceramic magnets (expensive, bought via mail order.) The stack of supermagnets must be about the same size as the ceramic magnet stack.
- Instead of winding 300 turns of wire, wind 3,000 turns. Use wire that's about 3X thinner (like #40 gauge.) But does anybody have the time and patience for this job.
- Instead of spinning the magnets at ten times per second (600RPM,) spin them 10X faster at 6000RPM. You'll need some sort of drive-belt or gears to step up the speed. Try Dr. Gupta's trick with the hand-crank. The magnets might fly apart, so glue them and wrap them in black tape or even fiberglass resin. You'll also need real bearings and not just holes in cardboard. And grind the resin to balance the magnets so they don't vibrate the bearings to death.
See what's going on here? Most kids can't build a generator if they tried any of the above techniques.
But here's a thought: do all of the above suggestions, but do each of them only half-way. Like so.
First build a tiny generator using small supermagnets stuck on a tiny nail run through the side a plastic pill bottle or 35mm film can. The magnets must flip end over end as usual. (Instead use "rattlesnake egg" magnets, or "buzzing bee" magnets, and glue little rods to the tips as an axle.) Then wind lots of turns of thin wire on the plastic bottle (500 turns is good, but more is better. Use thinner wire, like #35.) Finally, use some "invisible gears" to step up the generator speed. Build your invisible gears like so: first build a 6-inch rotating wooden disk with a hand-crank, then glue supermagnets on the rim of the disk facing outwards. Or even use a hamster wheel instead. (Space the magnets about an inch apart, with all poles facing the same way.) Place the tiny plastic-bottle generator close to the rotating magnet wheel. The magnets on the wheel will spin the magnets inside the pill bottle.
Now spin the wheel, and the generator spins extremely fast. And you've improved the generator in three ways. The magnets on the wheel will spin the tiny generator at high speed without touching it. The strong supermagnets in the plastic bottle will give a stronger field than the black ceramic magnets. And the extra turns of wire will create extra induction. All this together should produce a much higher voltage than the Ultra-Simple cardboard generator.
You could even build two of the pill-bottle thingies, or three or six. Then somehow position them all around the magnet wheel. Spin the magnet wheel, and all the supermagnets spin. Hook the coils all in series, then twist each coil so it gives out maximum volts. Then connect the crank to a hamster wheel, or to a windmill.
3. WHERE CAN I BUY THIS?
Nothing here for sale. But you can find generator kits from several suppliers on the links page.
4. WIND POWER GENERATOR. HOW TO MAKE ONE?
Sticking fan blades on the cardboard generator probably won't work; it turns too slowly and won't light the bulb. To run a bulb, this simple cardboard generator must spin very very fast. Fan blades probably won't spin it fast enough. So how about this instead: don't light a bulb! Instead, buy an $5 AC voltmeter. For science fairs, instead of running a light bulb, you can just display the AC voltage created by the wind power.
A wind generator might light a bulb or an LED if you wind 1000 or more turns of wire onto the cardboard. Or, you could try using two large (expensive and dangerous) supermagnets instead of four black ceramic magnets. Or look just above, in the part about making a tiny generator that uses a wooden disk and "magnetic gears."
Finally, here are some adult-level DIY wind generators over on the links page. These may give you some ideas. Also look at Arvind Gupta's DIY hand-crank generators.
5. HAMSTER GENERATOR?
Can we build a hamster-powered generator? Maybe. (See above .) If you only wrapped 250 turns of wire on the cardboard, the hamster won't be able to run a light bulb. Hamsters can't run fast enough.
People have lit up some LEDS using hamster generators with supermagnets and custom-wound coils. Or instead, don't bother making light, instead just measure the hamster voltage made by your lego blocks generator.
6. CAN WE BUILD A MORE POWERFUL GENERATOR?
Store-bought electrical generators are exactly the same as motors. To see what a hundred-watt generator looks like, buy a large DC motor and take it apart. (Treadmill replacement DC motors can be found on eBay.) Spin the shaft of any DC permanent magnet motor, and electrical energy comes out through the motor connections. Even tiny DC motors will act as generators. If you want to make higher voltage, then buy a motor that runs at 24V.
But if you really really want to build your own professional generator, take a look at the do-it-yourself wind turbine hobbyist sites. They've designed "pancake shaped" generators which can be built without machine tools such as mills or lathes. These generators work by passing some flat coils between powerful supermagnet slabs. They're designed to work at low speed, since wind turbines rotate at low speed with high torque.
Note that a powerful generator requires a powerful source of "work" to spin it, such as a gasoline engine. Human muscles don't do much: if you hook a bicycle to an electric generator, an adult can produce about 50 watts, but it takes exhausting effort. Professional atheletes such as bike racers can only create a couple hundred watts (as with MacCready's Gossamer Albatross flying across the English Channel in 1979.)
7. CAN IT CHARGE A BATTERY?
This AC generator makes the charges in the wires wiggle back and forth. It's alternating current.
AC can light a bulb, but it unfortunately it can't charge a battery. To recharge a battery, you have to pump charges in one direction through the battery and back out the other side. If you use AC, the battery just charges and discharges over and over again. The energy never builds up inside.
Also, a rechargable battery requires more than one volt DC, while this generator creates only 1/2 volt AC. The voltage is too low because the generator turns slowly and also it doesn't have enough turns of wire to reach the battery-charging voltage. (NOTE: it would be easier to charge a supercapacitor instead of a battery, since supercapacitors don't need a minimum voltage. But they do need DC rather than AC.)
To convert the generator to DC, just wire a diode in series. See making DC. A diode is like a one-way valve for charges. But most diodes need a bit of voltage in order to work. They won't work at all until the generator gets to around 1/2 volt. So you'll have to double the amount of wire on your generator. (Or if you're really ambitious, don't use a diode, instead build an entire commutator assembly that fits on the shaft. A "commutator" switch is the usual way to create a DC generator. But a diode is much simpler.
If you really want to recharge a 1.2 volt NiCad battery, add a diode to create DC. Then you must either spin the generator WAY WAY faster. or wind far more turns of wire. A thousand turns would be good.
8. WHAT'S MY HYPOTHESIS? (For science fair?)Some science fairs demand that you write a "hypothesis." Real scientists simply think up questions to answer. Your hypothesis is your guess at what the answers might be. But these must be questions that your investigation can answer. Here are a bunch. Now think up some more on your own:
- Can this generator light two light bulbs wired in parallel? More?
- What amount of wire is necessary to light one bulb? How few turns?
- What AC voltage is created? (Get a cheap DVM digital voltmeter.)
- What's the maximum AC current?
- Can this generator drive a loudspeaker?
- Which types of flashlight bulbs or LEDs can this generator light up?
- How fast must we spin it when using two magnets instead of four?
- Will small cheaper magnets work better? How about supermagnets?
- Can this generator be converted into a motor? What volts needed?
For science fairs, you'll get a higher grade if you do things with math rather than verbally. Make measurements and draw some tables and graphs. For example, you could figure out a way to tell how fast the magnets are turning. Maybe use a non-electric hand drill, so you can tell the revolutions per second. Then measure the generator AC volts for different speeds of magnets. Then plot a graph of RPM versus speed. That answers the question of maximum voltage. Or for a different experiment, always spin the generator at the same speed, but remove more and more turns of wire while measuring the volts. Then you can make a graph of number of wire-turns versus output voltage.
9. USE THE TWO OTHER SPOOLS OF WIRE?
The wire kit from Radio Shack only has one spool of thin #30. Can we use the other two spools? No, unfortunately. They are short and thick. They'll only add about 50 more turns of wire. To make a real difference you need to add hundreds of extra turns.
Much better to track down a cheap source of wire from mail order. Look at the parts list, and see if any of those surplus sources are selling open-frame 24volt solenoids.