| Science based toys such as microscopes and | | | | disadvantages, I call it the speakerphone, and it is |
| chemistry sets are a great way to learn about the | | | | surprisingly easy to make. |
| world around us. We learn underlying scientific | | | | To make a speakerphone you will need two |
| principles whilst we play, sometimes without even | | | | speakers from an old stereo or a pair of old car |
| noticing. There are many science toys on the market | | | | speakers, preferably with a small amount of speaker |
| but in my opinion the best educational toys are the | | | | wire still on them. |
| ones you can make yourself. | | | | Purchase a roll of speaker wire or similar two core |
| The first science toy I ever made was the old | | | | cable, and use this to join the two speakers |
| favorite 'Plastic Cup Telephone'. I first saw this on | | | | together, terminal to terminal using either solder, or if |
| Blue Peter and it consisted of two plastic cups with a | | | | you managed to leave a small amount of the original |
| taut string joining them, the idea was that when | | | | wires in place, simply strip the wires back about |
| somebody talked into one of the cups the vibrations | | | | 10mm and twist them together with the new wire, |
| would travel down the taut string and into the other | | | | taping over later with insulating tape. |
| plastic cup where the vibrating cup would cause the | | | | After this you should have the + terminal of speaker |
| air in and around it to also vibrate, and so recreating | | | | 1 connecting to the + terminal of speaker 2 and also |
| the original sound waves. | | | | the - terminal of speaker 1 to the - terminal of |
| This is not much different from how a real telephone | | | | speaker 2. |
| works except that electric current replaces the | | | | Your speakerphone is complete! Now as you speak |
| vibrating string in a real telephone. The string phone I | | | | directly into a speaker, the sound waves from your |
| made back then worked well enough and filled me | | | | voice cause the speaker cone to vibrate, as this |
| with pride as my brother and I relayed secret | | | | vibrates it causes a small copper coil to vibrate over |
| messages to one another much to the annoyance of | | | | a magnet generating an electric current in the wire. |
| our little sister. But this vibrating string method had a | | | | This current travels through the speaker wire to the |
| rather serious drawback, the string needed to be | | | | other speaker. As the current runs through the small |
| taut and allowed to vibrate without anything touching | | | | copper coil at this end it turns the coil into an |
| it. And since this meant that it could not be used | | | | alternating magnet, which due to its proximity to a |
| around corners our efforts to communicate from | | | | large permanent magnet begins to vibrate in exactly |
| bedroom to bedroom came to nothing, however we | | | | the same way as the first coil which generated the |
| did learn quite bit about science that day. | | | | current in the first place. This coil is attached to the |
| I have made many more science toys [ since that | | | | speaker cone so causes the cone to vibrate which in |
| one, and have recently made another telephone | | | | turn causes the air to vibrate recreating our original |
| which does not share the cup and string cornering | | | | sound wave. |