Supercon 2022: Tap Your Rich Uncle To Fund Your Amateur Radio Dreams

February 23, 2023 by Dan Maloney 11 Comments

Imagine you had a rich uncle who wanted to fund some of your projects. Like, seriously rich — thanks to shrewd investments, he’s sitting on a pile of cash and is now legally obligated to give away $5,000,000 a year to deserving recipients. That would be pretty cool indeed, but like anything else, if it sounds too good to be true, it probably is, right?

Well, maybe not. It turns out that we in the amateur radio community — and even amateur radio adjacent fields — have a rich uncle named Amateur Radio Digital Communications (ARDC), a foundation with a large endowment and a broad mission to “support amateur radio, funds scholarships and worthy educational programs, and financially support technically innovative amateur radio and digital communications projects.” As the foundation’s Outreach Manager John Hayes (K7EV) explained at Supercon 2022, ARDC is a California-based 501(c)3 non-profit organization that has been in the business of giving away money to worthy projects in the amateur radio space since 2021.

Continue reading “Supercon 2022: Tap Your Rich Uncle To Fund Your Amateur Radio Dreams” →

Know Audio: Amplifier Nuts And Bolts

August 24, 2021 by Jenny List 31 Comments

As we’ve followed a trail through Hi-Fi and audio systems from the listener’s ear towards the music source, we’ve reached the amplifier. In our previous article we gave a first introduction to distortion and how some amplifier characteristics can influence it, and here we’ll continue along that path and look at the amplifier itself. What types of audio amplifier circuits will you encounter, and what are their relative merits and disadvantages?

A Few Amplifier Basics

Horowitz and Hill's Transistor Man — Horowitz and Hill’s Transistor Man

If you know anything about a transistor, it’s probably that it’s a three terminal device whose output pin forms part of a potential divider whose state is dependent on what is presented to its input pin. The Art of Electronics had it as a cartoon of a man standing inside a bipolar transistor and adjusting a variable resistor between collector and emitter while watching an ammeter on the base.

Properly biased in its conducting range, a transistor can behave as a linear device, in which the potential divider voltage moves in response to the input in a linear relationship, and thus the voltage on the output is an amplified version of the voltage on the output. This is the simplest of transistor amplifiers, and because different types of amplifier are referred to by lettered classes, it’s known as a class A amplifier. Continue reading “Know Audio: Amplifier Nuts And Bolts” →

DIY Hidden Bookshelf Speakers

May 11, 2011 by Mike Nathan 10 Comments

hidden_speakers

[Steve] was tired of looking at the speakers in his workshop and began searching around for something a little more aesthetically pleasing. Having recently received a set of hollowed out books used for hiding things as a gift, he thought that he might be able to solve his speaker issue in a similar fashion.

He grabbed a couple of books from a local thrift store and promptly removed the pages. They were replaced with cloth-covered plywood to make the device more sturdy while simulating the look of pages.

He mounted his speaker inside one of the books, and in a second installed a small 7W Class A amplifier. A third book houses a padded compartment to hold his iPod, completing the set.

[Steve] reports that the speakers are pretty much undetectable, and the sound quality is decent too. In fact, we’ve started looking for some old books to re-purpose in our workshop as well.