LESSON 5  -  OTHER COMPONENTS

The piezo speakers used in Wonky Wire and Bagpipes are kinds of transducers. A transducer is so called because it converts energy from one form to another. Piezos convert electrical energy to sound energy. They are made of a special crystal which squeezes itself a little bit when a voltage is applied. If the voltage is switched on and off repeatedly then the piezo vibrates. This vibration in turn moves air molecules. If the vibration is fast enough then we sense the vibration as sound. The faster the vibration the higher the pitch. The MadLab piezos vibrate about 4 000 times a second.

Batteries provide the power for the MadLab circuits. The source of this power is a chemical reaction. Chemicals within the battery react with each other and release electrons. These electrons flow around the circuit connected to the battery and make things happen. Electrons flow out of the negative terminal of the battery, through the wires and components of the circuit, and then back into the positive battery terminal.

It takes energy to do this and so eventually all the energy in the battery is used up. Occasionally the acid in the battery messily leaks out before it has been used and the battery has to be discarded.

Rechargeable batteries can have energy put back into them which reverses the chemical reaction. This allows the battery to be used over and over. The MadLab batteries however can only be used once. Once the reaction has taken place it cannot be reversed.