View source for CEB Press/Manufacturing Instructions/Controller Box/Construction Video Script-Soldering

The CEB Press Controller Box is an electronic control box that runs the Compressed Earth Brick Press.  Part of its assembly requires two LEDs, each soldered to a 100-Ohm resistor, and this video explains how to solder these.  To accomplish this, you will need a soldering iron, a soldering stand, pliers, a spool of soldering wire, a wet paper towel, two 100-ohm resistors, two light emitting diodes (LEDs) and a multimeter.

Prepare your soldering iron, which needs to be plugged in to heat up and should be safely mounted on a soldering stand so that the hot tip will not burn you nor start a fire by being left on a table.  Soldering irons will burn skin as readily as they melt solder, so focus, care and attention is critical for your safety. Fumes from soldering can be dangerous, such as the fumes from rosin flux which is at the center of soldering wire used to remove metal oxides while soldering, but is corrosive, so eyes must be protected and care must be taken to avoid breathing in the fumes. With your soldering iron securely on its stand, plug it in to let it heat up. It may take several minutes for the soldering iron to reach soldering temperature.

LEDs have two wires or leads, distinguishable by the lengths of the wires. The positive wire, which is longer, will be connected to a positive terminal while the other wire is negative and will be the wire we will connect to the 100-Ohms resistor. Using a pair of pliers, bend the tip of the negative wire into a small hook.

Make another hook in one of the two wires of the 100-Ohms resistor, and hook the LED and resistor wires together by those hooks. Use the pair of pliers to mash the hooks together; this will help make the process of soldering these two components together much easier.

Before we begin actual soldering, it is important to note that the soldering process will cause the LED and resistor wires to become very hot. They will become too hot to touch, so do not handle the wires directly during nor after the soldering process; instead, use a pair of pliers. Also, electronic components can incur damage from too much heat, so you will need to solder as quickly as possible to avoid letting too much heat build up that can damage the components, especially the LED. Keeping a grip on the LED wire will help alleviate both problems as the pliers have much more mass and are more resistant to overheating, and will actually absorb some of the heat spreading along the wire and therefore prevent heat damage to the LED.

Wipe the tip of the soldering iron after it has heated to clean oxides from the surface of the soldering iron that might infringe the thermal energy transfer process.

Now it is time to set up to solder these two resistor/LED pairs. Set up your solder spool so that the end of the solder wire is bent up, so we can easily access it hands-free. "Tin" the soldering iron by touching the tip of the iron to the end of the soldering wire, just enough to get a small bead of molten solder at the tip of the soldering iron. This will help improve the transfer of heat from the soldering iron to the wires, where we will want them ... when we solder, we will not be touching the soldering iron to the soldering wire directly, but touching it to the wires, causing them to heat up so their joint can be touched to the soldering wire, melt the solder and absorb it in a bead. Touching the soldering iron to the soldering wire during the actual soldering process would draw the bead onto the iron instead of the wires where we want it. In sum, the soldering iron heats the joint, and the joint melts the solder.

Remember that the actual soldering process must go quickly, as prolonged heating of the wires with the soldering iron can damage the LED; also remember the wires will be too hot to handle with your fingers directly, so handle them only with the pliers. Do so now by gripping the LED joined with the resistor using the pliers on the LED side of the wire, and carefully grip the plugged-in soldering iron with your other hand. Heat the joint we made between the resistor and LED wires by touching the hot soldering iron near the joint, and quickly touching the joint, not the soldering iron, to the soldering wire. If the wires are hot enough, the solder will melt readily and draw up into the joint. Quickly remove the iron from the wire and replace the iron on its stand, and set down the resistor/LED to allow the solder to cool. The soldered joint should have a silvery luster, which indicates a good solder.

Repeat this process on the second resistor/LED pair, then clean the tip of the soldering iron by wiping it on the wet towel, tin the tip to prevent oxide formation on the tip during non-operation, and then unplug your soldering iron to let it cool. Warning: It may take several minutes before the soldering iron cools to the point the tip would be safe to touch, so let it sit for awhile on the soldering stand.

Give the wires and their solder some time to cool before we handle them for the next step. After they have cooled, test the resistance of the joint with a multimeter; they should have zero or almost zero resistance.