Home > Articles

This chapter is from the book

Prototyping Circuits

To use solar cells, you need to level up your skills in laying out circuits. After a certain point, you need a way to connect and organize the wires and components. This section offers two ways; the first is using a solderless breadboard, which is a quick and easy way to prototype circuits. I’ll also show you how to solder, which uses conductive metal to stick components together. It’s fun!

How to Breadboard

As you can see in Figure 4.7, the breadboard consists of a grid of wire holes. What you can’t see is that conductors are hidden in the plastic, so some of the rows of holes are linked together and some aren’t. So, without ado, let’s examine a breadboard’s architecture:

  • A.Ground bus—The ground bus is the strip of holes marked with a blue or black line. All the holes in this strip are linked together and typically are used for ground connections. Simply plug in the bus to your Arduino’s ground pin or the negative terminal of a battery pack.
  • B. Power bus—The power bus is configured the same as the ground bus and marked with a red line on most breadboards. Plug your power supply here and then connect components as needed to power them.
  • C. Terminal strips—These rows of holes are connected in groups of five, as marked in Figure 4.7. The various holes are given letters and numbers to help you organize your circuits.
  • D. Notch—The notch in the center of the breadboard separates the two sides—none of the hidden conductors cross the notch. If you want to connect the two sides, you’ll need to use wires! When breadboard projects involve integrated circuits or microchips (ICs), the chip is usually positioned to straddle the notch, and this provides limited air cooling.

    FIGURE 4.7

    FIGURE 4.7 A solderless breadboard is a convenient prototyping platform.

Here’s an example of a simple breadboard project. Look at Figure 4.8 and follow along:

  • 1. Plug in a resistor from the power bus to one of the terminal strips. I used a 10,000-ohm resistor (known as a 10K, Sparkfun P/N COM-11508). It doesn’t matter which wire goes where.
  • 2. Plug in an LED. I used one of Sparkfun’s violet LEDs (P/N COM-12704) and it ended up rather dim. You might try swapping in a lower value of resistor. LEDs are polarized, meaning that one lead is positive and one is negative, and if you put it in backward, the LED won’t light up. Put the long lead of the LED (positive) in the same terminal strip as the resistor. The short end (negative) plugs into the ground bus.
  • 3. Attach a 9V battery to a battery clip (Jameco P/N 109154), with the red lead plugged into the power bus and the black lead plugged into the ground bus. The LED should light up!

    FIGURE 4.8

    FIGURE 4.8 This simple project will show you how to use a breadboard.

How to Solder

Breadboarding is well and good, but the best way to connect wires and components—assuming everything is working the way you expect—is to solder them. In this section, I’ll take you through a very quick but thorough guide to soldering.

Soldering Toolkit

You’ll need the following supplies to solder:

  • Soldering iron—These come in many shapes and price points. You don’t have to spend a lot of money to get a quality iron, but the Radio Shack cheap one is not the solution. The two irons I use are a Weller WES51 (just Google that P/N to find one) and an Xytronic XY-258 iron (Adafruit P/N 180) that I keep in my toolbox.
  • Solder—Solder comes in a great number of formulations and gauges. Here’s a great solder and I use it for all of my projects: 0.31—gauge, rosin-core, 60/40 lead solder. You can buy it anywhere (Adafruit has it, P/N 145).
  • Sponge or tip cleaner—It’s important to keep your iron’s tip clear of residue, such as melted jumper insulation and baked-on flux. Some irons, like the aforementioned WES51, have a sponge that comes with it, but many soldering pros swear by tip cleaners like the Hakko 599B (Adafruit P/N 1172), which features a tangle of brass foil that cleans your iron without the need for a wet sponge.
  • Vise—Small tabletop vises like the Panavise Jr. (Sparkfun P/N TOL-10410) help keep the printed circuit board (PCB) secure while you solder. Often they have suction cups or mounting holes for added security. You can usually hold the PCB in your hand or keep it on the table, so a vise is optional.
  • Solder sucker—This is a tool for sucking up molten solder. Sparkfun has a cheap one
  • Diagonal cutters—Use this for clipping off leads after you’re done soldering. Sparkfun has an inexpensive pair (P/N TOL-08794), and Adafruit has a nicer set made in Italy (P/N 152).
  • Fume extractor—Soldering releases some toxic fumes. An ordinary desk fan or a specialized fan called a fume extractor (Jameco P/N 2171786) will keep those noxious gases away from your respiratory tissues.

Anatomy of a PCB

Electronic projects usually include a printed circuit board, or PCB. These typically consist of a sheet of laminate embedded with traces (wires) and solder pads, which are the tiny plates onto which the components are soldered. There are also instructions screen-printed on the material. Let’s take a closer look at the typical circuit board in Figure 4.9:

  • A. Circuit board
  • B. Screen-printed information
  • C. Solder pads
  • D. Traces

    FIGURE 4.9

    FIGURE 4.9 Screen-printed labels show you how to assemble the PCB.


Although soldering may seem dangerous—hot irons and lead poisoning!—I’m happy to say that it’s actually quite safe, as long as you follow some basic guidelines:

  • Beware of what your soldering iron’s tip is touching. The tip is upwards of 600 degrees and can start fires and burn skin. However, tip burns are part of the soldering experience and can be treated as you would any burn.
  • It’s suggested that you wear eye protection when clipping leads. These are the wires sticking out of electronic components, and they can go flying when clipped, potentially injuring you in the eyes. Better not to risk it.
  • Solder is made out of lead, and that means that you shouldn’t ingest it. You should make a point to clean your hands and workspace after soldering. The latter can be cleaned up with ordinary household spray cleaner to make sure you’ve collected as much lead particulate as you can.
  • The fumes are also toxic. You should solder in a well-ventilated room or use a fan or fume extractor to keep those fumes away from your face.

Let’s Solder!

If you have all the stuff you need, you’re ready to solder! I’m illustrating the process by assembling a Blinky Grid kit from Wayne & Layne (wayneandlayne.com or Adafruit P/N 549), so if you’re intrigued, you know where to find one.

Follow along with the simple steps outlined in the following sections:

STEP 1 Set Up the Work Area

You usually want your soldering iron close at hand, as well as a nice work surface. If you want accessories like a fume extractor or vise, now is the time to grab them (Figure 4.10).


FIGURE 4.10 Want to solder? Gather all your tools together.

STEP 2 Heat Up the Iron

Some irons don’t have an “on” switch; you just plug them in. If it’s got a switch, turn it on. Often an iron will have a temperature selector; if it does, set it to about 650 degrees, as you can see in Figure 4.11.


FIGURE 4.11 Plug in your iron and heat it up!

STEP 3 Tin the Tip

The first word in soldering iron maintenance is to “tin” the tip—basically, coating it in solder. This helps transmit heat, and if you tin your tip early and often, you will be rewarded with a hotter iron. Just touch the iron to a piece of solder and turn the iron around until the tip is coated, as you can see in Figure 4.12.


FIGURE 4.12 Coat the tip of your iron with solder.

STEP 4 Insert the Component

This is fairly self-evident. Components have wires sticking out of them, called leads. The circuit board normally indicates if a component is polarized. This means the leads have to be inserted in a certain way on the PCB. Also on the circuit board are little metal disks pierced with holes. These are the solder pads. Slide the component’s leads through the holes in the solder pads, just like in Figure 4.13.


FIGURE 4.13 Insert the component, making sure you got the polarity right.

STEP 5 Bend Back the Leads

Turn the PCB around so you’re looking at the back. Bend the leads of the component (as you can see in Figure 4.14) so it won’t fall out when you solder.


FIGURE 4.14 Bend the leads back to keep the component from falling out.

STEP 6 Solder the Joint

Touch the iron’s tip to the lead and the solder pad for three seconds (Figure 4.15) and insert the end of a piece of solder. The solder should flow into the hole and rise into an even little hill.


FIGURE 4.15 Just add solder!

STEP 7 Examine the Joint

Before you move on, take a gander at the connection. It should be a neat little hill, like in Figure 4.16.


FIGURE 4.16 A successfully soldered connection looks like a tiny hill!

STEP 8 Resolder as Necessary

Suppose your solder joint looks like the one in Figure 4.17—gooping up two solder pads. Grab your solder sucker, a spring-loaded piston that sucks away melted solder. Press down the plunger, then melt the solder with your iron while holding the solder sucker close. When the solder starts to flow, press the button on the piston and it will suck the solder away.


FIGURE 4.17 Too much solder? Grab a solder sucker.

STEP 9 Clip the Lead

When the solder joint looks the way you like it, clip the lead as close to the joint as you can manage (see Figure 4.18). Ready for the next component!


FIGURE 4.18 Clip the excess lead off. You’re done!

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020