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.

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!

How Do I Use Digilent Products at School? (Digital Edition)

As you learned from my previous post (the Analog Edition version of this post), we used the Analog Parts Kit and Analog Discovery in EE352 at Washington State University (WSU) to make an AM radio transmitter and receiver. Not only do we use Digilent products in EE352, but we also used Digilent parts in EE324 (Fundamentals of Digital Systems) — the digital lab class I was taking.

Shields vs Pmods: Good vs Better?

Today we’re going to compare two different ways of increasing the functionality of a system board: Pmods and shields. Those of you have that have been following the Digilent Blog know that Pmods are Digilent’s series of peripheral modules with 6-12 pins that can easily be connected to appropriate pins on a system board to provide extra functionality and include audio amplifiers, GPS receivers, USB to UART interface, seven-segment displays, accelerometers, H-bridges with input feedback, analog-to-digital converters, and much more. For the rest of you who have been in this sector of the electronics industry, you know that shields are a type of board that you can plug directly on top of your microcontroller in a nice pin-to-pin fashion for expanded functionality. Although you might suspect which of these two items I prefer, we’ll check out the advantages of both of them.