When you have a small stock of vacuum fluorescent displays (VFDs) straight out of the 1976 Radio Shack catalog, you might sit around wondering what to do with them. When [stepawayfromthegirls] found out that his stash of seven DT-1704A tubes may be the last in existence, there was no question. They must be displayed! [stepawayfromthegirls]’ mode of display is this captivating clock build. Four VFDs with their aqua colored elements are set against a black background in a bespoke wooden case. Looking under the hood, the beauty only increases.
Keeping the build organized was not an easy task because the tubes are designed in such a way that each segment must be individually controlled. The needed I/O duties are provided by an Arduino Mega 2560 Pro (Embed). 28 2n3904’s each with their two resistors serve as drivers for each VFD segment.
The output of a 24 V AC transformer left over from the 1980s is rectified to 34 V of DC power which is then regulated to 27 V to power the tubes. Switching power supplies provide 6 V to the Arduino and 1.3 V to the filaments. If you look closely, you’ll also see a GPS module so that the clock doesn’t need to be set. To future-proof the clock against daylight savings time adjustments, a potentiometer on the back of the case allows the user to set custom hour offsets without editing any code.
We think the end result is a remarkably clean, simple, and elegant clock that he will be proud of for many years to come!
There was a time when Radio Shack offered an incredible variety of supplies for the electronics hobbyist. In the back of each store, past the displays of Realistic 8-track players, Minimus-7 speakers, Patrolman scanners, and just beyond the battery bin where you could cash in your “Battery of the Month Club” card for a fresh, free 9-volt battery, lay the holy of holies — the parts. Perfboard panels on hinges held pegs with cards of resistors for 49 cents, blister packs of 2N2222 transistors and electrolytic capacitors, and everything else you needed to get your project going. It was a treasure trove to a budding hardware hobbyist.
But over on the side, invariably near the parts, was a rack of books for sale, mostly under the Archer brand. 12-year old me only had Christmas and birthday money to spend, and what I could beg from my parents, so I tended to buy books — I figured I needed to learn before I started blowing money on parts. And like many of that vintage, one of the first books I picked up was the Engineer’s Notebook by Forrest M. Mims III.
Many years rolled by, and my trusty and shop-worn first edition of Mims’ book, with my marginal notes and more than one soldering iron burn scarring its pulp pages, has long since gone missing. I learned so much from that book, and as I used it to plan my Next Big Project I’d often wonder how the book came about. Those of you that have seen the book and any of its sequels, like the Mini-notebook Series, will no doubt remember the style of the book. Printed on subdued graph paper with simple line drawings and schematics, the accompanying text did not appear to be typeset, but rather hand lettered. Each page was a work of technical beauty that served as an inspiration as I filled my own graph-paper notebooks with page after page of circuits I would find neither the time nor money to build.
I always wondered about those books and how they came about. It was a pretty astute marketing decision by Radio Shack to publish them and feature them so prominently near the parts — sort of makes the string of poor business decisions that led to the greatly diminished “RadioShack” stores of today all the more puzzling. Luckily, Forrest Mims recently did an AMA on reddit, and he answered a lot of questions regarding how these books came about. The full AMA is worth a read, but here’s the short story of those classics of pulp non-fiction.
[Pat] may not be the world’s most dangerous secret agent, but he does have Woodhouse taking care of his home. [Pat] has been upgrading his sonic screwdriver home automation system these past few months. Waking up to a chilly room led him to start hacking a thermostat interface. [Pat] found that his furnace only needed one 24VAC wire to be shorted to a common during a call for heat. [Pat] was lucky in that his thermostat was low voltage. While researching a thermostat hack, we made the painful discovery that our thermostat is 120VAC, so watch for that if you try this one at home.
[Pat] connected his thermostat leads to a relay controlled by a Raspberry Pi. The Pi would read a temperature sensor and set the relay accordingly. That was fine for a quick hack, but opening an SSH window to change the temperature isn’t the most convenient thing in the world. Enter an old Asus Transformer Prime tablet. [Pat] coded up an Android Holo style interface using AJAX along with HTML/CSS/jQuery and PHP. OpenMic+ constantly listens for voice commands, and fires them off to Tasker tasks as needed. He calls the results Woodhouse, and the interface is very slick. The tablet controls and graphs temperature, [Pat’s] media center, and his lights. Woodhouse is even [Pat’s] right hand man when getting ready for those intimate moments. We can’t wait to see what [Pat] comes up with next.