While browsing one of our favorite electronic supplier’s web sites, we found that Ladyada sells a really interesting looking clock that uses a vacuum florescent display with eight glowing digits. This clock proved to be an excellent soldering instruction project for a younger Rusty Nail Workshop helper.
The most interesting feature is the display, which is similar to those found on VCRs, old car radios, and microwave ovens. The vacuum florescent display was invented in 1967 in Japan and hundreds of millions are used annually around the world. They are different than an LCD in that they use a filament to emit electrons which are diffused by grids. The electrons strike a phosphor-coated plate and emit light, and can be manufactured to emit light in different colors.
This kit comes with numerous electronic parts, all of which must be hand soldered to a printed circuit board. The instructions from Ladyada are excellent, and each step is accompanied by a helpful photograph. Our first step in the assembly process was to take an inventory of the parts we had received. Everything was accounted for, although some of our capacitors were slightly different than those in the Ladyada instructions, but not confusingly different.
The soldering is fairly straight forward, and the instructions clearly show the orientation for components such as diodes and capacitors. In fact, the instructions had photographs every step of the way, and one could even install the components just by looking at the photos, if desired. The hardest part was the insertion of the vacuum tube leads onto its associated circuit board. There are a high number of leads and they are very flexible, so inserting them one at a time took some effort.
Along the way, the instructions suggested the clock be plugged in to test various components. This was helpful and provided reassurance that the soldering was going according to plan. After everything was soldered, the circuit board is assembled into an acrylic laser-cut case. This not only provide a nice way to display the clock, but also protects the user from the high voltages found on the circuit board from the boost circuit.
The brightness of the display is adjustable, so you will not blind yourself at night. I also believe that lowering the brightness will help prolong the life of the vacuum tube, and thus the life of the clock. In the future, it should be fairly easy to add a GPS module to allow the clock to set itself from the atomic time kept by the GPS satellites. There are plans for this modification (or as we like to say “hack”) widely available for those that want to make this upgrade.
Overall, this was a very fun project. The completed clock shown below was assembled (completely) by a thirteen year old. I think he did a rather nice job!