Two DigiKey Calculators that Makers Need to Know About

2021-12-22 | By Maker.io Staff

Engineers and makers know DigiKey for the extensive online catalog that offers the world’s largest selection of electronic components available for immediate shipping. Besides its engineering-centered online catalog, DigiKey offers a wide range of convenient services for makers and engineers alike. Previous articles investigated the DigiKey PCB Builder, a service that lets you get quotes for your custom PCB designs from many different board houses without even needing to create a user account. This article takes a look at the DigiKey calculators, another extensive, practical, and professional service that you can use online for free.

How to Access the DigiKey Calculators?

To access the DigiKey calculators, head over to the DigiKey website and click on Conversion Calculators on the Tools card on the store’s front page:

Alternatively, you can also use the main menu located below the search bar. For that, hover your mouse over the resources entry and then click the ‘Conversion Calculators’ link from the ‘Tools’ submenu:

Two DigiKey Calculators that Makers Need to Know About

On the DigiKey calculators page, you’ll find numerous handy calculators and conversion tools commonly used in electrical engineering and physics. Currently, the website offers 31 converters and calculators. However, DigiKey constantly works on adding new ones to the website, and you can also request a tool that you’d like to see on the website in the future.

Two DigiKey Calculators that Makers Need to Know About Scroll down on the calculator’s overview page and use the last entry in the list to request a new calculator. The button takes you to a feedback form where you can describe which calculators you'd like to see in the future.

Available tools include converters for lengths, weight, force, and inductance. The calculators section comprises tools like a 555 timer calculator, voltage divider calculator, Ohm’s law calculator, and a resistor color-code calculator.

This article specifically discusses two tools that are particularly useful for makers: the LED series resistor calculator and the battery life calculator.

A Closer Look at the LED Series Resistor Calculator

As mentioned, the LED series resistor calculator has often proven to be one of the most convenient tools for me. I use it whenever I plan to employ LEDs in one of my projects to make sure that I select a current-limiting resistor that suits the LEDs I want to use:

Two DigiKey Calculators that Makers Need to Know About

As you can see, this calculator allows users to input three values. The first value is the supply voltage, which is either 5V or 3.3V in most DIY projects. In the other two fields, you supply the forward voltage and forward current. These depend on the LED you want to use. Next to the calculator, you can see a region with related products. These links will quickly take you to the appropriate category in the DigiKey store for you to select components that match your project’s requirements. Below the calculator, you can find a table that lists typical forward voltages values depending on the LED color. However, let’s look at an example with a concrete LED in mind.

Suppose you wanted to use this red 5mm through-hole LED. First, find the forward voltage and forward current in the product description:

Two DigiKey Calculators that Makers Need to Know About

Then, transfer those values to the LED series resistor calculator and input your project’s supply voltage. In this example, let’s suppose I’m using an Arduino UNO board that operates at 5V. There’s no need to push any buttons. The calculator shows you the optimal resistor value as soon as you fill in the required values:

Two DigiKey Calculators that Makers Need to Know About

As you can see, the calculated optimal value is 145 Ohms in this example. You can then use the related products section to search the DigiKey catalog for a matching resistor.

Use the Battery Life Calculator to Find the Perfect Battery for Your Project

Finding a suitable battery for your DIY project can be a difficult task to get right. Once you’ve decided on the type of battery you want to use, you must consider its capacity next. Using an oversized battery in your project adds unnecessary cost and weight. An undersized battery offers too little runtime, and you might end up charging your project more often than actually using it.

For beginners, it can be challenging to estimate a battery-operated project’s runtime. For that purpose, the DigiKey website offers a handy tool that quickly shows you approximately how long your project will run with a given battery. You can then experiment with different capacities to see how they affect your project’s runtime. Once you’ve determined a battery capacity that works for you, the tool suggests a few batteries that fit your requirements.

Let’s look at a concrete example. Suppose your Arduino project runs on 5V and draws around 200mA during regular operation. You decide to use a 1300mAh battery pack in your project, and you plan to recharge the battery every 24h. How long will your project run with this setup? The battery life calculator quickly helps visualize the runtime:

Two DigiKey Calculators that Makers Need to Know About

As you can see, this project would run for approximately six and a half hours before you need to recharge it. Next, you can experiment with the battery capacity and device consumption until you reach the desired runtime of 24h. Once you’ve found a size that meets your project requirements, you can use the ‘Search Catalog’ button to find suitable batteries:

Two DigiKey Calculators that Makers Need to Know About

As you can see, this project could operate for 24h with a 4800 mAh battery, and the tool suggests a battery that’s readily available and meets the project requirements.

Summary

DigiKey is not only a supplier of electronic components and lab equipment. Our website also offers a few handy services for hobbyists and engineers, such as the DigiKey PCB Builder and online calculators. As of writing this article, you can choose from 31 online calculators that you can access without a user account and free of charge. This article took a closer look at two of these tools, namely the LED series resistor calculator and the battery life calculator. The LED series resistor calculator allows you to determine the perfect current-limiting resistor for a given LED. You can then use the DigiKey catalog to find a resistor that matches your requirements.

The battery life calculator visualizes a battery-powered project’s runtime so that you don’t need to guess the approximate runtime anymore. Once you’ve determined what capacity your project’s battery needs to be, the tool can search the DigiKey catalog for you so that you can quickly find the perfect battery for your project.