The methods described use a variety of materials and tools, so, if you don't have all the materials for one method you can just look at a different method. If you are having trouble finding supplies and tools, a stop at your local hardware or electronics store should supply the necessary tools. In this Instructable I have rated the different methods' strength according to the scale low, medium, and high strength. If you are making a temporary circuit or project, the low category methods would probably be best to use because they allow easy disconnecting after you have made a joint. However, if you are making a permanent circuit or a project that moves around a lot, the medium or high strengths would probably be best so that you don't have joints coming apart in the middle of an experiment.
Before you begin, you need to learn a few basics when connecting wires. Most wires are coated in a plastic insulator. An insulator is something that protects the wire from heat and prevents other wires from touching. When you are connecting wires you need to have a bare end without insulation. The term for removing insulation from a wire is called "stripping the wire." You will need a pair of wire strippers/cutters, a pair of pliers, and a spool of stranded wire. First, look at your wire strippers and look for the holes that have a number labeled next to them. The number represents the hole's gauge or width. The smaller the gauge number the wider the wire. Look on your spool of wire and find out what gauge your wire is. Next, cut off a small piece of wire from the spool (start with 4", this wire will just be for practice). Insert 3/4" of the wire into the hole in the wire strippers with the appropriate gauge. Grip the other end of the wire with pliers or very strong fingers and pull the wire strippers towards the closest end of the wire. After a little pressure the plastic insulation should slide off, revealing the stranded wire underneath.
Another thing you need to know before we get started is how to twist two wires together. In all the methods described except for the "crimping method" and the "alligator clip method" you will need to start with the wires twisted together. To twist two wires together, you first need to strip the insulation off the wires. Next, hold the wires side by side and twist them together with your thumb and forefinger. The resulting connection should be fairly strong and hold together when a small tug is applied. Now that you have learned these skills you are ready to learn four ways to connect a wire without soldering.
Alligator Clip Method/ Strength: Low- The alligator clip method is the weakest method described in this Instructable, but it is perfect for quick and temporary connections. The alligator clips' ability to snap in place almost anywhere is very handy to not only connect wires, but also to pin things down and hold things up. What you need: a package of alligator clips (available at RadioShack, not the kind that is already connected to wires), two wires with stripped ends.
Hold the two stripped ends of the wires parallel to each other. Snap an alligator clip onto them, making sure the "teeth" touch both wires. Wasn't that easy? You can also buy alligator clips that are connected to wires or you can make your own.
Electrical Tape Method/ Strength: Medium- The electrical tape method is fairly strong and only requires a minimal amount of supplies and effort. This method would be useful for permanent connections that need insulated joints. What you need: a roll of electrical tape and two wires whose ends have been twisted together.
First, lay the twisted part of the wires onto a strip of electrical tape. Wrap the tape around the wires tightly 5-6 times, making sure to cover up all the wire. Give your connection a tug to make sure it is strong.
Hot Glue Method/ Strength: High- The hot glue method is a strong joint that not only connects the wires, but also insulates them. The glue cools quickly so you don't have to clamp down the wires. What you need: a hot glue gun and sticks (available at your local hobby store), a set of wires with twisted ends.
First, heat up your glue gun. Once heated, hold the glue gun perpendicular to the twisted wires and squeeze a glob of glue onto them. Next, with the nozzle of the glue gun or a pencil, swirl the glue around the wires. Swirling the glue forms a better bond then just leaving the glob of glue how it is. Make sure that the entire part of stripped wire is coated in hot glue, and then let the hot glue cool.
Crimping Method/ Strength: High- The crimping method is by far the strongest method described and requires the most specialized tools, but, with a little practice, can be used with mastery. The tools are available at your local hardware or electronics store or online. What you need: a crimp (sometimes called cord crimps) or a thin piece of metal tubing 3/4" long (the tubing must be able to conduct electricity), a crimping tool, and a pair of stripped wires.
First, insert the stripped part of one of the wires into the crimp, all the way up to the insulation. Repeat this process on the other wire. Next, place the crimp in the notch in the crimping tool. Squeeze the tool until the crimp crushes and bends into a "U" shape. Keep doing this with the rest of the crimp until you have a rut going down the length of the crimp. Give your wires a strong pull to make sure they are connected well. Crimping can take practice, so don't be discouraged if it doesn't work the first time.
In this Instructable we have explored four different ways to connect a wire without soldering. Hopefully you can use these methods in your circuit and projects.