Soldering Basics and Breadboarding Tricks

Have you ever wondered how to create a more permanent version of the makeshift circuit you put together on a solderless breadboard? The typical solution to this issue is to use something called a perfboard, or a solderable breadboard. At the end of this guide, you will have learned the fundamentals of soldering breadboards and have assembled your own simple LED circuit.

You will need the following:

Perfboard/Breadboard

2x 2 kOhm Resistors

2x LEDs (any color)

Solder

Soldering Flux

Soldering Iron

Brass Wool (for cleaning the iron)

Optional, but helpful:

Helping hands soldering stand

Solder vacuum

Before we begin soldering, we need to have a design first.

For this tutorial, I have created a simple circuit diagram consisting of two LEDs in series with the appropriate resistors which in turn are in parallel with a 9v battery.

In case you're curious about why we need resistors, they prevent the diodes from drawing an unrestricted amount of current from the battery. These resistors act as current limiters, which puts a cap on how much current a LED may draw. The specific value of these resistors varies based on the voltage and the LED's current rating, and we can determine this through Ohm's Law

Voltage = Current * Resistance

We are using a 9v battery, and a typical LED is rated for ~15mA. If we plug those values into the formula and solve for the resistance, we can determine the minimum value needed for our resistors.

9V = .015A * R

R = 9V / 0.015A

R = 600 Ohm

2kOhm resistors are a bit excessive for LEDs powered by a 9v battery, but it allows us a good margin of error while still allowing them to function properly (they were also the only resistors I had that were above 600 Ohms).

With the theory out of the way, we can get started with preparing our tools.

Tinning the tip of your soldering iron is one of the most important things you can do for the longevity of your tool. It prevents any oxides from accumulating on the tip of the iron, which can damage it. Tinning also provides a good thermal transfer from the iron to the solder, which makes soldering much easier.

In order to tin your tip, all you need to do is melt some solder on the tip of your iron and remove any excess solder with the brass wool. You should have a shiny silver tip on your iron.

(Please do NOT use steel wool, it WILL damage your soldering iron!)

You should always tin your tip before, during, and after your session. Get into the habit of frequently tinning your tip, even if you believe its fine. Your soldering iron (and wallet) will thank you.

With your iron prepared, we may now begin soldering the components to the breadboard.

Begin by arranging the components on your board according to the schematic, making sure to leave yourself a bit of space between parts so that you can fit the soldering iron in. Pay attention to which way the LEDs are oriented. The longer leg of the led should be directly next to a wire from the resistor. You may find it helpful to bend the legs of the LEDs so that they may sit in the board a bit easier.

Once the components are placed on the board, dip your soldering wire in some soldering flux. You can never have too much flux! Take your fluxed wire and place the tip on pads where the leads of the components are. Place the tip of the soldering iron against the same pad the wire is on so that both the pad and the wire are contacting the hot iron tip, taking care not to scorch the breadboard. It should only take a few seconds for the solder to melt into the hole. When this happens, you may proceed to the next component until all parts are soldered to the breadboard. Repeat this process on the underside of the circuit.

With the components securely soldered to the breadboard, we may now make connections between them. This part is typically the most tedious of the process. Trial and error is the best way to learn here.

On the underside of the circuit, melt plenty of solder between the leads of the LEDs and their respective resistors. Make sure to use a liberal amount of flux here as we do not want any oxides breaking the electrical connection between each contact.

Fold a lead of a resistor over to the lead of the other resistor and solder them to the nearest pad where they intersect. This technique is much more reliable than running a bead of solder or using a piece of solder as a wire, so try to use this whenever you're prototyping your own designs.

Fold the legs of the LEDs so that they line up with each other and solder them to the nearest pad. If there is a gap between them, run a good amount of solder between the legs. This may take more solder than you think, so don't worry if it doesn't seem to work at the start.

The final step is the most annoying to deal with. We will use some of our solder as a wire. This is generally used for making long connections between components. Due to the low melting temperature of the solder however, it is difficult to solder the ends of the wire to the board without accidentally shortening the board.

If you have access to non-stranded, high gauge wire, consider using that instead of solder.

With everything soldered to the board and all the proper connections made, it is time to connect our 9v power source to the circut to see if everything works. You should have two LEDs that light up when the battery is connected. If they light up, congratulations on assembling your first breadboard circuit.

If your LEDs do not light up, check your circuit for the following problems:

• Battery polarity. Try reversing the contacts
• Battery charge. Is the battery dead?
• Incorrectly oriented LEDs. Are the legs positioned right?
• Traces. Are any connections broken?

If you are prototyping your own circuits and are satisfied with the design, you can either leave it as is, or consider scaling up to professionally made PCBs. This sounds daunting and is beyond the scope of this tutorial, but you only need to create a PCB layout from this point forward, which is much easier than it sounds. Look around for PCB layout tutorials in software like KiCad.

Once you have the layout files, you can send them off to a manufacturer, such as OshPark.