Here is a great little Numitron based clock that used a flat style display tube instead of the normal circular envelope. The flatpack displays go by several names including Pinlite or Minitron. They all work on the same principal - they are incandescent filament displays. The major difference between them are the shape, the electrical connection, and any included logic to make implimenting them easier. You can find more information about them here at Surplus Sales of Nebraska.
This particular unit is for sale on eBay. It has a 6 digit numitron display and, according to the auction, has had a few digits replaced. I don't know what is uses for an internal time base and it isn't readily apparent from the photos. However, since these were made for the FAA and DOT, I would assume that they are more stable than your average home built nixie clock.
The last few I've seen of these on eBay have sold for around $175. Considering that this is an industrial piece of hardware with a limited production and unusual display, that is probably a fair price. I haven't seen these outside of eBay before and I can't seem to find much other information about them.
Well after 2 years+ I found 2 more of these clocks. I am selling one and may consider selling the other one. I had 3 that I sold on E-bay a couple of years back for over $120.00 each. These are very rare, I have only seen 2 others listed ever on E-bay. The auction for one just ended. That clock went for $184.00 plus about $15.00 shipping. The auction number is (320385126217) If you check my feedback you might be able to find the reference to them. The buyers were very very happy with them. This unit is being offered with a low starting bid and no reserve. I personally hate reserve auctions. I am offering this clock with a buy it now price of $179.00. If you purchase it at the buy it now price I will thow in free basic shipping in the lower 48 states( does not include insurance). For international bidders I will drop $10.00 off the shipping cost.
Interesting 24 Hour Numitron Clock using 6 plug in flatpack numitron displays. Made for the US government, Department of Transportation, Federal Aviation Administration. Type FA-10046 S/N 1836. Contract DTFA01-84-C-00036 Made by C & G Associates Limited. Acceptance date on bottom of May 23, 1986. Just what you need for your retro control tower simulator in your basement.
Unit contains 21 IC chips and is crystal controlled. The processor chip is a Motorola MC6802P with an EPROM next to it. Circuit board is glass epoxy, well made. The displays are Numitron incandescent 7 segment readouts. This unit contains 6 plug in displays in a flatpack style that looks like an IC chip with a glass cover. The seconds displays are smaller than the hours and mins. This clock had segments burned out in both of the seconds displays and the single minute display. These probably went first due to how often they are switched. I was able to find NOS unused displays to replace the bad ones. I will include the old bad ones if you want them. I have a couple of extra displays that I may list later. The displays are FFD71F for the seconds and FDD81F for the mins and hours. These can still be purchased but are expensive new from the large electronic supply houses. Because the display is incandescent it can be filtered to any color. Please note that the brighter you run the display the shorter the life span of the filaments. At a lower light level the displays will last a very long time. The clock has been tested and keeps good time. Has inputs for some kind of time code, FAA E and IRIG E. These connections are brought out on the back with 2, three pin connectors, male and female that are wired in parallel.
To use as a clock simply plug in to 120V 60Hz then all the numerals will flash. Turn the selector switch to Preset and use Hour and Minutes buttons to set. Turn to switch to Clock and it starts counting. Test button lights all segments on displays. Intensity sets the brightness. Clock has removable color filters, green for the hours and mins and red for the seconds. The filters just drop in so any color combination could be used. Measures 8.75" Wide, 2" tall, 8.25" deep. There is nickel on top of the clock in the front picture.