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.
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.
In mid 2012, I noticed an amplifier on eBay that was out of a 1952 Rock-ola 1436 jukebox, and just had to have it. It was essentially a dead carcass, so I decided to restore the amplifier and make it able to stand alone. I wanted to make the restored amplifier as authentic as possible to the 1952 version.
For audiophiles, musicians, and ham radio operators, the soft glow of the vacuum tube filament is not only an indication of function, but a nostalgic trigger for memories of simpler times. Though they may have been outpaced by tiny transistors and integrated circuits, these workhorses still may have something to offer in many modern devices.
Over the years, I have accumulated a bunch of chips from before the era of true PCs when computers with names like Altair, KIM-1, and Cosmac ELF were popular. I’ve been looking for a way to use them in new projects, so I designed a system around a 40-pin PIC16F887. I figured this would put some of my historic chips to work and be a great learning tool for understanding how a microcomputer works.
This six-digit, beautifully designed timepiece showcases cold war era components — Numitrons instead of Nixie tubes — along with modern LEDs and a Microchip PIC to create not only a useful clock but a great conversation piece as well.
