Everything for Electronics

# Learn Electronics

After reading the May-June 2018 NV article on Ohm’s law, I thought a follow-up article that goes a little deeper might be in order. Specifically, how Ohm’s Law together with a computer and a couple of tricks can be used to calculate the time dependence of much more complex circuits involving not just resistors but capacitors, inductors, op-amps ... you name it! In this article, I’ll describe a simple numerical method that is intuitive and solves many complex problems with just a few lines of code. No simulator needed!

#### DIY Biotech: A Spectrophotometer for Measuring Bacterial Growth

Build an Arduino-based spectrophotometer to explore how the optical density of bacteria suspended in a liquid can be used to measure the rate and stage of bacteria growth.

#### Libraries and Headers in C: A Tutorial

If you’ve written a program for a microcontroller board such as the Arduino, Raspberry Pi, or Propeller QuickStart, you have relied on software libraries that provide constants and functions.  Often, we use software libraries without thinking much about them.

When you start to write libraries, it takes time to read documents, follow directions, and experiment with simple functions. Fortunately, after you understand how to create libraries and header files for the software tools you use, you'll have a useful skill that can simplify programming tasks.

Even if you never create a library, you probably want to know how they work and what they contain. This tutorial provides information that gives you a good start.

#### The Radio Station that Bridge Built

It was 1923, and radio was the phenomenon of the day. Over 600 broadcast stations were on the air, and Americans bought 100,000 receivers that year. (Sales would jump to 1,500,000 in 1924.) Many owners hosted “radio parties” and danced to the latest jazz music with their friends. At the same time, the game of Bridge was sweeping the country. Read how one card company used this “new technology” to promote their products.

#### CNC Routers: Backlash

Backlash can have a detrimental effect on tool life and on your CNC router’s ability to maintain accurate positioning of the X, Y, and Z axes. In this article, we’ll look at the problem of backlash in CNC routers. Once you understand what role it plays, you’ll want to diminish its impact on your machine. Whether you own or intend to build/buy a CNC router, make it a habit to routinely check for backlash. It could save you some money and/or aggravation.

#### The Smith Chart

The Smith Chart turns the complex mathematics of transmission lines into circles and arcs that unlock the mysteries of SWR, stubs, matching networks, and a whole lot more. It’s an amazing tool that brings the arcane math of transmission lines to visual life so you can understand them.

#### How to Learn CW

Even though CW is no longer a required component of amateur radio license tests, it’s still a practical and fun skill to learn. Plus, these days, there are many different learning aids readily available.  All you need is the discipline to spend 10-20 minutes/day practicing and you’ll be sending and receiving CW before you know it.