I used some masking tape to hold the Mouser Pins in place as I soldered them in from the bottom side.

       I needed to make a couple of spacers to bolt the two boards together. This way they would not come apart from each other. I used some aluminum spacers and 4-40 screws to sandwich the boards together keeping them solidly connected. Notice the longer bolts below, they were used as a temporary stand for the clock.

       After only a few hours I was able to power up the kit and see if my new IN-18 tubes would light up. I connected my 750 ma 12 volt AC adaptor to my outlet and voilla, my tubes were burning. I set the anode voltage to about 175 volts once the tubes had been burning for ten minutes. Letting them warm up gives you the most accurate voltage setting.

       So far so good!!! The IN-18 tubes are looking magnificent. I proceeded to test out every tube including the spares I bought for proper operation in the board. If I listened very closely I could hear the tubes oscillate from the multiplexed driver signals and “sing” their beautiful tune. The metal cathode symbols seem to oscillate when the pulsed voltage hits them.
       One of the great advantages of using multiplexed tube drivers is that it saves overall tube life as the tubes are not burning on 100% of the time. Actually they are sequenced or pulsed off and on many times a second giving the illusion through “persistence of vision” that they are burning all the time.
       I wanted to add a few options to the kit including a battery backup and blinking colon separators. Both of these modification were laid out in the instruction manual and easily followed. There was a bit of design on my part when It came to adding a small circuit board to hold the components for the blinking colon separator neon lamps but the circuitry was right out of the manual.

       I used a Radio Shack 9V Nickel-Metal Hydride battery for the backup battery. The battery is charged by the clock and will prevent the time from being lost when a power outage is experienced.

       My overall intention for the Nixie clock would be to house it in a wooden enclosure so I installed remote switches for the clock controls as well as a remote power jack (shown later). I also added an optional relay to turn off the tubes when a 12 volt DC control signal voltage is not present. This way I can remotely control the tubes with a remote control signal and tie it into a light switch or my entertainment system power. This will allow me to save tube life by only using the clock when I am in the room.
       I connected up the tube saver relay in series with the 12 volt power to the DC to DC converter (not shown). This way the clock is still operating but with no anode voltage.  With IN-18 tubes currently costing about $25 a piece I want to make sure I get the most viewing pleasure out of them. The kit does include a tube saving option but nothing that can be controlled by an remote binary source. Note: This modification will render the tube hour counter useless as the PIC processor thinks the tubes are always on.

       I really wanted to make an enclosure that matched my entertainment center cabinet where the clock will eventually be placed. I figured the best way to recreate the cabinet look would be to use some mahogany wood with a dark stain finish. Finding mahogany is not as easy as it seems but with eBay anything is possible :0) I ended up buying some scrap pieces of mahogany board for $10 on eBay. This would be the first time I had ever worked with a “real” hardwood.

       I proceeded to sketch out a “craftsman” style design for the clock enclosure and sorted through the pieces of wood for the best grains. I then cut out the center section of the clock enclosure very carefully on my scroll saw. I was impressed at how solid this wood is.

       I used my trusty belt sander to square up the outside faces of the box and test fit it on the clock boards. Notice the colon separator neon lamps that I added below. I picked them up on eBay and used 200K ohm ballast resistors on each of them. An MPSA42 transistor was used to switch the neon lamps anode voltage off and on (Illustrated in the kit manual, also see the schematic).

       The top and bottom of the clock enclosure were the next thing to create. I saved the best looking piece of mahogany for the top of the clock enclosure. My design would follow the 45 deg. bevel that my entertainment system cabinet has on the top.

       I used my scroll saw to cut a crude 45 deg. bevel on the edges of the two pieces and then fine tuned the cut with my belt sander.

       I test fit the pieces together and so far it looked great. Although it kind of looks like a miniature casket at this point :0> Overall I was impressed with working with the mahogany. It is so solid and cuts so well that no wonder it is used for fine woodworking projects. I guess I am simple to please :0))

       To get the clock to fit into this enclosure I would need to countersink the electronics into the top piece by cutting a trough in the top piece. I did this by using my mill equipped with an end mill bit. When I was done the wood was only about a 1/4” thick at the top of the enclosure. The strength of the mahogany made this process simple. (A router equipped with a rectangular fence would work as well, the mill was just convenient for me to use.)

       The next step was to carefully cut out the hole where the tubes would be installed. I layed out these holes with a compass and proceeded to drill a pilot hole just under the size needed for the tubes. The holes were then fine tuned with my Dremel tool using a 1/2” sanding drum.

       The strength of the mahogany wood allows the holes to be so close to each other. A lesser wood would have chipped where the holes get close to each other.

       A hole was made in the bottom piece to allow clearance for the backup battery. The pieces were then drilled on either side for two mounting screws that hold the enclosure together like a sandwich.

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