As a native of Northern Minnesota, I’ve been a longtime DigiKey customer. I can remember my first DigiKey purchase: I walked to the front door and asked for a part – no call ahead and certainly no internet back then. It took half an hour, and I was on my way with resistor in hand and a paper catalog that was about half an inch thick.
Many years later, I return as an application engineer.
Please allow me to share my strategy for resistors.
What resistors should I include in my parts kit?
The answer depends on the type of electronics that interest you. For this post I will answer assuming you are a hobbyist or student interested in a wide range of electronics including analog circuitry and microcontrollers. This material will also be useful for an educator attempting to equip a general electronics lab. This post will also provide tips that allow you to quickly locate a particular resistor.
My resistors are stored in two distinct locations. The often-used resistors are in a single bin next to the workbench. The parts selection is limited, but it covers many of my needs. I find that ¼ W resistors are useful with 10, 100, 220, 1.0 k, 2.2 k, 10 k, and 100 kΩ values. This bin as pictured in Figure 1 also includes common capacitors, diodes, transistors, MOSFETs, and regulators. This bin provides a good start but is not enough for all my work.
Figure 1: Author’s bin of common electronics components with focus on resistors. Capacitors are visible in the background
The remainder of my resistors are organized and stored on shelves. Decades ago, I purchased two kits from DigiKey including RS150 and RS250. These complementary kits include the majority of ½ W resistors from the E-24 series. Here the term E-24 indicated that there are 24 resistors per decade. For example, in the decade from 10 to 100 Ω, there are 24 unique values starting at 10, 11, 12, 13, 15, progressing to 75, 82, and ending at 91 Ω. The table in Figure 2 shows how the resistors are selected for each kit where the RS150 parts are highlighted in green and the RS250 parts are highlighted in yellow. Also note that the term E-24 implies that the resistors have a 5% tolerance.
Figure 2: Highlighted resistor selections for DigiKey kits RS150 and RS250, for easy identification of the resistors contained in each kit.
Solution found in DigiKey resistor kits
DigiKey clearly designed this kit with an eye toward cost. For example, I first purchased the RS150 kit. This provided a wide range of resistors suitable for many projects. Sometime later, I purchased the RS250 kit to fill out the E-24 series. Still later, I purchased one of the related kit, either RS125 or RS225 kit which provided the same values but this time as ¼ W resistors with the same 5% tolerance.
The importance of component organization
At this point, we should talk about organization. There are 144 unique resistor values in the two kits. To save time it is important to organize the resistors so that a particular value may be quickly located. It’s also important so that the bins may be restocked from time to time. There are many ways to do this. My solution was to use poly bags as shown in the picture in Figure 3. You can see that each row in the box contains a decade of resistors. That’s 24 unique values per row.
Figure 3: The author has arranged the resistors in poly bags, organizing them by decade in each row, for example, 100 to 910 Ω.
In addition to the ½ W resistors, the box provides storage for a variety of larger resistors as well as overflow for the common types. In Figure 4, you can see a large wire wound 50 Ω resistor along with a collection of 2 and 3 W devices used when I built a few audio amplifiers.
Figure 4: The author’s storage bins also house a range of larger resistors, including 2 and 3W in poly bags along with a collection of larger resistors some up to 50W in size.
As you can imagine after building, repairing, and experimenting for several decades there are many more resistors in my lab. This includes kits for surface mount products resistors and a variety of 1% precision values.
I’m sure you will build your inventory. My personal recommendation is to purchase the kits and then purchase extra parts for any specialty devices you used in a design or repair.
Best Wishes,
APDahlen
P.S. Please share your stories showcasing your workspace organization. I’m particularly interested in small spaces such as when your work is done at the kitchen table.
Pictures are most welcome.
About the author
Aaron Dahlen, LCDR USCG (Ret.), serves as an application engineer at DigiKey. He has a unique electronics and automation foundation built over a 27-year military career as a technician and engineer which was further enhanced by 12 years of teaching (interwoven). With an MSEE degree from Minnesota State University, Mankato, Dahlen has taught in an ABET accredited EE program, served as the program coordinator for an EET program, and taught component-level repair to military electronics technicians. Dahlen has returned to his Northern Minnesota home and thoroughly enjoys researching and writing articles such as this.