Here is an easy, economical way to make a very small, polarized connector with any number of pins for just pennies. A polarized connector ensures that the plug and socket ends are not joined with reversed electrical connections, which could cause severe damage to some electronics.
Step 1: Reversing Connections Is Physically Impossible
As you can see from the image above, it is physically impossible to mate the polarized connectors.
Step 2: With Polarization, Your Connections Cannot Be Reversed
There is no need for color coding your wiring, but I still recommend it.
You can mate connectors even when lighting conditions are poor and be assured that your connections are correct every time.
Step 3: Here Are the Tools That You Will Need
Wire stripping/cutting tool
side cutting pliers
Soldering iron (15 to 30 watts with fine point)
Hot glue gun (preferably with a fine nozzle)
Metal rule (or equivalent)
Hot air gun (optional)
Emory board or sandpaper (optional)
Good lighting over your workbench
Step 4: Here Are the Supplies That You Will Need
20 to 26 gage stranded copper wire (color coding is optional)
heat shrink tubing to fit your wire size
fine, rosin core solder
male and female header strips
Step 5: Skills Needed
Basic wire stripping and soldering skills
Step 6: Select the Number of Pins That You Want to Use
Select the number of pins you need to connect and cut them from both the male and female the header strips. Note that the female side is cut a one half space beyond what is needed and then trimmed. Take the emory board or sandpaper and smooth any rough edges.
Step 7: Preparation for Soldering
Cut the wires to the length needed. Strip the wire ends back about one eighth inch. Lightly solder (known as tinning) the ends of the wires and the short end of the pins on the headers. Use masking tape to secure the wire and headers while tinning.
Step 8: Soldering the Wires to the Connectors
Cut one quarter inch pieces of heat shrink tubing and before soldering, slide them over the tinned ends of the wires keeping them about half an inch from the ends. Trim the tinned ends to the same length as the short pins on the headers. Tape the headers and wires to your work table and solder the wires to the pins of the headers. You can use the emory board and side cutters for clamping and fine alignment.
Now clean your iron on a wet sponge, melt a very small amount to solder on the tip, and then solder the wires to the header pins. Tug on the wires to make sure you have a good, solid, shiny joint.
Step 9: Shrinking the Insulation Tubing
After the solder joints have cooled, slide the tubing over the joints so that the solder joints are completely covered. You can use your soldering iron or a hot air gun to shrink the tubing. If you use a soldering iron, gently rub the iron over the tubing and keep the iron moving. DO NOT skip this step.
Step 10: Preparing the Headers
Connect the headers exactly the way you want them to mate. Use the emory board to rough up the TOP side of the female header and the BOTTOM side of the male connector. ( Or vice versa, just be sure to do the top of one and the bottom of the other). This will help the hot glue to stick in the next step.
Step 11: Here Begins the Magic...
Place the male connector's rough side up and tape it down to your workbench. Liberally dust the ruler with talcum powder to prevent the hot glue from sticking to the ruler. Place the metal ruler OVER the pins. Use tape to secure everything. Now carefully place a blob of hot glue over the roughened header AND overlapping the metal rule which is laying over the header pins. Shape the blob with the side of the glue gun nozzle if necessary.
If you place too much glue you can trim it after it cools or just peel it off and start over. Wait a few minutes until the hot glue cools and hardens, then remove the metal rule.
Step 12: Building the Female Connector
Repeat the above step for the female header making sure that you apply glue to the roughened side of the female header. You may need to shim the rule up to be level with the female header housing as shown here or stick some pins into the female header and rest the rule on top of the pins. Use lots of talcum powder and let the hot glue cool before removing the rule.
Step 13: Congratulations!
Your finished polarized, multi-pin connectors should look like this (or even better than this ;-))
Enjoy and by all means have fun making stuff !