A quick tutorial on the proper method of making connections in the middle of a wire. Read through completely before starting.
First, make sure you have all the tools and parts before you start. Then, decide where you want the connection to be, taking into account anything that may be in the way, allowing enough wire length, and sufficient room for the connection.
1 -- The most common mistake: Laying the wires against each other, soldering them together, and wrapping them with tape.
This creates stress points that will fail and cause the circuit to quit.
2 -- Proper method: Wrap the leads of the diode around a toothpick to create a loop just large enough for the wire(s) to pass through, and cut off excess wire past the loop.
3 -- Run the wire(s) through the loop, gently squeeze the loop closed to hold the wires in place without cutting into them, and twist them around as shown. Clip off any excess wire.
At this point, the connections should be sufficient to test the circuit for proper function. Make sure none of the exposed connections are touching anything, turn on the key and activate the circuit -- if it works, proceed. If not, the diode may be in backwards, or a connection is loose. Correct any problems, retest, and proceed with soldering.
3 -- Making sure the wires are coming out from the loop straight, solder them, making sure that only enough heat is applied to solder, and only enough solder is added to make the connection -- you should be able to see the outlines of the wires through the solder. If you are not sure, practice on scrap wire until confident.
4 -- Bend the leads of the diode back against the body, being careful not to stress the leads or short them together.
5 -- Retest the circuit, slide the heatshrink over the connection, making sure that it ia completely covered, and heat the tubing with a heat gun of some sort. Unless there is no alternative, do not use a match or other open flame for the heat source -- it can cause a fire or burn the tubing.
---- Some notes about the heatshrink tubing: remember to slip the tubing onto the wires before making connections! (don't ask how I know this.) Also, it is available now with a sealant on the inside which melts and seals the connection when heated. Use this whenever possible.
This may sound obsessive, but better 10 minutes of obsessive than 3 hours of cursing over a failed connection 2 months from now.