Teardowns of vintage gear in which you carefully note component values, construction techniques, and create a schematic from scratch are a great introduction to vacuum tubes. The next level (and the focus of this article) is to restore tube-type devices, starting with a tabletop radio. Not only will you learn to work with the technology, but you’ll have something of value when you’re done.
In this article, I’d like to share how the primitive crystal sets of the ‘50s and ‘60s worked and hopefully stir some distant memories for those of you who also built one of these mysterious listening devices. I also hope that you’ll consider introducing your kids and/or grandkids to the world of crystal sets.
One hobby that’s prevalent today is restoring antique radios. Once you have an antique radio, it’s nice to listen to it. Unfortunately, the content of present day AM radio stations leaves a lot to be desired. There’s nothing comparable to the type of programming that was on the air in the heyday of radio broadcasting. The solution to this dilemma is to use a low power crystal-controlled AM transmitter to broadcast age-appropriate material to the antique radio. Such an AM transmitter is the subject of this article.
It took me eight months of part-time work to restore all 168 pounds of a Heathkit “H-1.” I would like to share a few of the trials and tribulations I went through to resurrect this beast.
When the concept of electromagnetic waves was first proposed around 1864, it was met with great skepticism. As a result, the idea languished for a long time. It took several decades for a handful of dedicated persons — infatuated with the mysteries of electricity and magnetism — to finally put the theory on a solid footing.
In this article, we’ll take a look back at this period that launched the serious study of radio waves. We’ll examine the contribution of James Clerk Maxwell, the man most responsible for the concept. Next, we’ll look at the work of several notable scientists who came after Maxwell, and see how they confirmed the existence of radio waves.
Magnetic loop antennas are becoming popular today because they can be very efficient for their size, do not need radials (even though most designs are vertically polarized), have useful takeoff angles, and can be easily rotated to peak or null a signal. Here’s how I designed a convenient setup for myself.
I use LCD displays in almost every project. However, in this modern age of steampunk, I stumbled on something much cooler — 1” high seven-segment electromechanical displays (EMDs) that go clickity, click. Here is an ambitious project that features five 1941 vintage rotary phone step-by-step (SXS) switches. These EMDs are the perfect match to display the dialed digits.