Learning to design your own PCBs and being able to put together a schematic to solve a specific problem is both a valuable and rewarding skill. There are a number of resources out there to help you avoid common mistakes, but it isn’t always obvious to know where the values of certain common components come from, particularly common parts like resistors and capacitors. Figuring this out is part of the learning process, but it isn’t always easy to know where to look since you first need to know exactly the right terms to search for.
Choosing the Right Crystal and Caps for your Design - [Link]
Analog Devices (who have a lot of great app notes locked up in their stable) have made available in PDF format enough good information and reading material to keep you busy for the rest of the winter while you wait for warm enough weather that you want to step outside again. Their Linear Circuit Design Handbook has a lot of excellent material, and can also be ordered in printed format if you’re still a fan of a good old highlighter and notes in the margin like me.
Linear Circuit Design Handbook - [Link]
Bypass capacitors ensure a device has a stable and clean power supply. In most cases capacitors are chosen out of habit, such as the typical 0.1uF ceramic capacitor we use.
This app note describes how calculate, model, and use different types of bypass capacitors. Included is a table with all the relevant information on different types of capacitors, and a few examples of different circuits that need different bypass capacitors.
App note: Choosing and using bypass capacitors - [Link]
Here’s Jeri Ellsworth’s latest video, explaining the basics of DSP and SDR for beginners, and how to build a digital direct conversion receiver (SDR) using sampling detectors and FPGA DSP processing. (If you want to skip the silly cat portion of the video, start at 1:25.) [via]
DSP/SDR basics - [Link]
Hang around any electrical engineer long enough, and you’re bound to hear the word inductance tossed around. Or perhaps if you’re hanging around people dealing with high-speed signals, an ugly little thing called “cross talk” might get mentionned a lot (hint: it has nothing to do with speaking in an angry voice to your troublesome PCB, or any uncomfortable attempt to proselytize it and save it from eternal damnation in a lake of molten solder). If you’ve ever wondered what either of these terms mean (and how they’re related), you might find it worthwhile reading this relatively accessible ‘app note’ of sorts explaining what inductance is and why it matters: What Really is Inductance? (by Dr. Eric Bogatin)
What Really is Inductance? - [Link]
Basics: Introduction to Zener Diodes @ Evil Mad Scientist Laboratories – [via]
Zener diodes are a special type of semiconductor diode– devices that allow current to flow in one direction only –that also allow current to flow in the opposite direction, but only when exposed to enough voltage. And while that sounds a bit esoteric, they’re actually among the handiest components ever to cross an engineer’s bench, providing great solutions to a number of common needs in circuit design.
In what follows, we’ll show you how (and when) to use a Zener, for applications including simple reference voltages, clamping signals to specific voltage ranges, and easing the load on a voltage regulator.
Basics: Introduction to Zener Diodes - [Link]
Collin’s Lab: Schematics – [via]
Schematics are the functional diagram of electronic circuits. With so many designs available on the web, understanding how to read schematics can unlock a world of possibilities for the electronics maker. In fact, if you can read a schematic, you can build a circuit before even understanding how it works!
Collin’s Lab: Schematics - [Link]
In this article I will tell you how to get shorter relay switching times and how to minimize relay current consumption. The same exact things apply to solenoids and solenoid valves.
You need to use a transistor because either relay you want to control needs a higher voltage than your microcontroller can provide, or relay’s current demand is too high. Although some microcontrollers can give enough current to switch a relay, but most of them is incapable of doing that.
And the diode in parallel with relay coil (or solenoid coil) is needed to suppress the flyback voltage that occurs when transistor is switching-off and magnetic field stored in coil collapses. That flyback voltage can reach hundreds of volts, which can completely destroy the driving transistor.
Using Relays (Tips & Tricks) - [Link]
A Beginner’s Guide to the MOSFET @ ReiBot.org. [via]
If you need to switch high current and or high voltage loads with a micro controller you’ll need to use some type of transistor. I’m going to be covering how to use a MOSFET since it’s a better option for high power loads. This guide will be just a brief introduction that will discuss how to drive a mosfet in a simple manner with the ultimate goal of making it act like an ideal switch.
Refer to the N or P channel basic wiring schematics and remember the three pins: Gate, Drain, and Source. When I mention something like Gate-Source potential difference, I’m talking about the difference in voltage between the two pins.
A Beginner’s Guide to the MOSFET - [Link]