Lab 1: Soldering


The purpose of this lab was to learn the skill of soldering. This is a very important skill for me to have in my Physical Computing class as I will be working with electronics. This lab showed me how to solder DC power jacks and plugs to connectors and battery holders for wiring up a breadboard. A light bulb on the breadboard illuminates if the lab is done correctly.



Dr. Hamid and Zane (an experienced solderer) briefed Garret (my partner) and I on the safety concerns of soldering. Dr. Hamid and Zane also prepared the soldering irons by powering them to an outlet and placing them in a safety holding device. We watched Zane perform a solder of a wire to a power jack and then it was our turn to do the same.


We first had to cut about four inches of both a red and black wire. We then stripped about 1/4 inch off both ends of the plastic coverings of both wires. We were told to leave only a small amount of copper exposed because we did not want the wires touching each other when it was time to build our circuit.

We then bent a hook on the stripped end of each wire. We unscrewed the power jack and connected the red wire to the hole in the center tab of the power jack, and the black to the hole in the outside tab. We used pliers to crimp the hooked wires to their connections on the jack.

After these preparations, we were then ready to solder.


Our next step was to solder the connections we just made. Garret and I took turns soldering the wire to the power jack. I held the wire and power jack while he held the solder and soldering gun for his turn, and vice versa for my turn.

We then soldered both wires to the header pin, being careful to ensure the wires do not touch. We then twisted the red and black wires together. We placed some hot glue at the base of the red and black wires to prevent electrical interference between the two wires. We also placed a rubber tubing on the black wire before soldering to the header pin to prevent electrical interference.

Next we soldered a separate pair of red and black wires to the power plug. This pair was already attached to a battery snap.

Here is our first completed component. The wires are connected to the header pin and power jack.


One problem we ran in to was that the tip of our soldering iron was not getting hot enough to melt the solder. We learned that because we had a new unused soldering gun, we had to invoke a process called “tinning”. This technique involves melting a little solder on the tip of the iron and then cleaning it off with a wet paper towel. This helps the heat flow properly from the tip of the iron to the joint. Once we properly tinned our iron, soldering became much easier.

We learned from Zane to “pre-solder” our wires for greater effectiviness when soldering.   We melted solder on to the wire before we made the connection. This made for a better, more secure connection.

Due to our inexperience in soldering, we had a couple “cold” joints. The solder on a good joint turns darker and no longer is shiny, ensuring you have a secure connection. On two of our joints, the solder remained metallic looking which Zane described to us as a looser joint, also known as a cold joint–the result of not enough heat from the iron applied to the joint. After we tinned our iron, we no longer had cold joints.

We tested both of our completed components with a multimeter to ensure we had proper connections.


After the soldering was finished, we then plugged the power plug in to the power jack. We snapped the battery snap on to the battery. We then plugged our head pin in to the breadboard and the whole setup powered an LED!

Garret and I were very happy with our soldering job.


One note to make is that once our circuit was complete, we lifted the battery in our hands and moved it around. This resulted in the LED flickering a bit. We attribute this to our cold solder joints that we did not fix earlier in the lab. If we left the battery sit on the table, our connection was just fine and the LED remained constantly lit.

Overall, this lab was engaging and very successful in teaching me to solder properly. I learned so much and I believe this knowledge will help me throughout the entire semester and beyond.

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