Your friends will wonder when they see a Computer Fan lighting an LED by generating Free electricity. Do you believe, the Computer Fan generates electricity when it rotates? Definitely very minute voltage of less than 1 volt is generating at full speed. But it is not sufficient to light an LED. So what happens when some Neodymium Magnets are placed on the Computer fan? Nothing happens specially because the Computer fan has 4 Electromagnets that become magnets only when we give 12 volt DC to it. So the Neodymium magnets are simply resting on the Computer Fan without doing anything. So let us do one Magic to trick your friends. Don’t forget to the reveal the trick after showing it because it is bad to fool others
What is the Neodymium Magnet?
Neodymium Magnet also called Neo Magnet is the most widely used magnets now. It is a kind of Rare earth Magnet and the permanent magnet of strongest type magnets commercially available now. If two magnets are coming close to 15 cm, they will attract and join with a sudden jerk. That much powerful. It is made up of an alloy of Neodymium, Iron and Boron.
Caution: Handle Neodymium Magnets with care. Its strong attraction with another magnet or metals may cause injuries in the hands. So handle with care.
How Computer Fan works?
The Computer Fan has four Electromagnets that become strong magnets of opposing polarity when a current of 6-12 volt is provided. It requires around 250 mA current to operate. Each Electromagnet has an Iron core with many windings of enameled copper wire. When current passes through the coil, the core becomes a Magnet. When the power is stopped, the core loses its Magnetism. So when the Computer fan is powered, the electromagnets become strong magnets and start to repel each other. This repulsion makes a rotation movement because it is free to move in a pivot.
Now let us make the Trick
1. Computer Fan
2. Four to Six Neodymium magnets
3. One LED
4. One Reed switch ( Normally Open Type )
5. One 3 Volt Button cell
6. Some wire
These are the steps to make the Tricky Computer Fan
Cut the Red wire and solder the Reed switch . Solder two thin wires to the other end of Reed switch. Hide the Reed switch in the groove for wires and apply some glue.
Now connect one thin wire to the Red wire removed . Place that over the Positive side of 3V Battery and paste insulation tape. Cut Black wire and join together. Place the joint part to the Negative of battery and stick insulation tape. Now this is the arrangement.
- The Red wire coming from the Fan is jointed to one end of Reed switch.
- The other end of Reed switch has two wires. One going to the Positive of battery and the other as out Red wire.
Now only two wires, a Red and Black coming out of the Fan if the battery is hided. Hide the battery in the groove of the fan. It remains like a Neodymium Magnet because of its size and shape.
Now place two Neodymium magnets on both sides of the Fan and paste insulation tape all around the fan. Remember, these Neodymium magnets doing nothing but creates a feel that, it is doing something.
Now connect the LED to the wires with correct polarity
Then take two Neodymium magnets.
Glue two Neodymium magnets on the back side of two opposing leaves of the Fan. So they are hidden in normal view. These Neodymium Magnets are doing the trick.
Now the Fan is ready with LED. In front view, it looks like a Normal Computer fan with LED connected to its wires and three Neodymium magnets fixed on the sides .
Now slowly rotate the leaf of Fan. When the Magnet on the leaf comes close to the Reed switch hided, by the influence of the Magnet, the Reed switch closes. This completes the path of current, so power from the battery flows through Reed Switch to the Red wire connected to the LED.Black wire is already has continuity with the battery. So LED Lights .Don’t show this to your friends. This is your confirmation test only.
Now place the Fan in front of a Table fan with the front side facing towards your friends. Don’t show the back side of Computer Fan . The Fan will rotate at full speed and the LED lights continuously.
Remember , this is only a Fun and at the same time you can learn how a Reed switch is working. The Reed switch has two thin electrodes in a glass tube. There are two types of Reed switches. Normally Open ( NO ) and Normally Closed (NC) types. In NO type, if a Magnet comes close , the contacts join and complete the path of current. In NC type, normally the contacts are connected and current flows. When a Magnet comes close, the contacts break and cut the current path.