How to Choose a Resistor for Your Design

Take a look at a circuit board and chances are you’re going to find a resistor or two. Most boards today use surface-mount device (SMD) technology, so the components are almost too small to see sometimes, but they are on there, I promise. How do engineers decide which resistors to use in the design? Sometimes it depends on how you want that portion of the circuit to perform, as in the case of an op-amp. Other times it’s to prevent too much current from passing through a given point in a circuit, which is why they are often called current-limiting resistors. Maybe you want a simple way to divide the voltage or current. The reality is that there are numerous ways to use resistors, and oftentimes, the defining the resistor value is up to you.

Why Do Electronic Components Have Such Odd Values?

If you’ve been around electronics for a while, you’ve probably noticed that components like resistors, capacitors, zener diodes and inductors come in some odd values. Looking at the chart above, there seems to be no clear rationale behind the values, but there is a pattern. 47kΩ resistors and 22μF capacitors are everywhere, but not 40kΩ or 50kΩ resistors, or 20μF or 30μF capacitors. So what’s the deal? It all has to do with preferred numbers.

Fun With the Project Box

We all know how much of a hassle it can be to safely transport your electronics, and let’s face it, the protective cases that many of our boards previously came in were flimsy, unaccommodating, and caused a great deal of stress for our customers. Well, we’ve responded to all of your feedback and I’m here to talk about our new Project Boxes!

History of the FPGA

As you probably know, one of Digilent’s major focuses is producing FPGA (field programmable gate array) boards and educating the public on FPGA design. One of the classes I was in last semester focused on FGPA design. This class is EE324 at WSU, which is taught by Digilent’s own Clint Cole. He gave a background lecture on the History of FPGA chips. Not only was it an extremely interesting lecture, but it also helped me understand the huge leaps in logic design that have been made since the 1960s. This is the history that led to the development of FPGA chips. The chips are the parts that Xilinx makes that we use on our FPGA boards.

Number Systems

Today, we are going to learn about number systems. A “number system” is defined here as “any notation for the representation of numerals or numbers.” We naturally use the decimal (base 10) system, meaning we use the numbers 0-9 to represent all the other numbers. The three types of number systems that we are going to talk about today are decimal, binary, and hexadecimal, but there are many more!

iLAB Analog – Practical Introduction to Analog Circuits

During the Christmas break, I ended up reading iLAB Analog, a new textbook written by Dr. Chen Yun Chao from National Taipei University of Technology Department of Electronic Engineering. I was excited to read a book that deals with both conceptual knowledge and has practical labs. For anyone who wants to learn about analog circuits but has very basic knowledge of physics, it is a good starting point. This book is currently being used in the Intro to Analog Circuits class held at National Taipei University of Technology.

New Product– the Nexys 4 DDR

Our new product, the Nexys4 DDR, is now available for sale! We have been anxiously awaiting this board’s release ever since we received an end-of-life notice from Micron (our memory provider) about cellular RAM that we had been using on all of our Nexys-class products. Rather than strip features off the current Nexys4, we decided to evolve the product line to accept DDR Memory. Check it out now!