Experiment 12: Joining Two Wires TogetherChapter 3104LoudspeakerTo complete the project in 142,Experiment 15, you’ll need a loudspeaker small enough to fit inside your project box but louder than the 1-inch speaker that you used previously. It should be 2 inches or 2.5 inches (50 to 60 mm) in diameter. If you can find a 100Ω speaker, it will give you more output, but an 8Ω speaker will be acceptable.Experiment 12: Joining Two Wires TogetherYour adventure into soldering begins with the prosaic task of joining one wire to another, but will lead quickly to creating a full electronic circuit on perfo-rated board. So let’s get started! You will need:• 30-watt or 40-watt soldering iron• 15-watt pencil-type soldering iron• Thin solder (0.022 inches or similar)• Medium solder (0.05 inches or similar)• Wire strippers and cutters• “Helping hand” gadget to hold your work• Shrink-wrap tubing, assorted• Heat gun• Something to protect your work area from drops of solderYourFirstSolderJointWe’ll start with your general-duty soldering iron—the one rated for 30 or 40 watts. Plug it in, leave it safely in its holder, and find something else to do for five minutes. If you try to use a soldering iron without giving it time to get fully hot, you will not make good joints. Strip the insulation from the ends of two pieces of 22-gauge solid wire and clamp them in your helping hand so that they cross each other and touch each other, as shown in Figure 3-31.To make sure that the iron is ready, try to melt the end of a thin piece of solder on the tip of the iron. The solder should melt instantly. If it melts slowly, the iron isn’t hot enough yet. Soldering Irons Get Hot!Please take these basic precautions:Use a proper stand (such as the one incorporated in your helping hands) to hold your soldering iron. Don’t leave it lying on a workbench.If you have infants or pets, remember that they may play with, grab, or snag the wire to your soldering iron. They could injure themselves (or you).Be careful never to rest the hot tip of the iron on the power cord that supplies electricity to the iron. It can melt the plastic in seconds and cause a dramatic short circuit.If you drop a soldering iron, don’t be a hero and try to catch it. Most likely you will grab the hot part, which hurts. (I speak from experience.) When you burn your hand, you will instinctively let go of the iron, so you may as well let it drop freely without the intermediate step of burning yourself while it’s on its way to the floor. Naturally, you should pick it up quickly after it does hit the floor, but by then you will have gained the necessary time in which to make a sensible decision to grab it by the cool end. Always bear in mind that others in your home are more at risk of hurting themselves on a soldering iron than you are, because they won’t know that it’s hot. Most soldering irons have no warning lights to tell you that they’re plugged in. As a general rule, always assume that a soldering iron is hot, even if it’s unplugged. It may retain sufficient heat to burn you for longer than you expect.