Single Numitron Clock
Four micro-sized yellow LEDs were used below the Numitron to indicate which digit is being displayed (HHMM); I would have used miniature incandescent light bulbs but didn't have any on hand. The clock is pretty small and the board measures approximately 1.25 inches by 1.5 inches. The original purpose of the software and circuit was to drive a single common-anode LED display rather than a numitron, but either way works. I modified the software to flash the digits so the HHMM leds wouldn't be necessary. Also the software was modified so if the tens of hours is 0 then it is not displayed. Moreover, the software does not check the input values so entering the wrong time such as 67:85 would be accepted, but eventually the clock will start resetting the digits correctly.
The .ASM file is the PIC assembly program for the clock. The .HEX file is the assembled program used to program the PIC, but choose the correct HEX file depending on whether you want to use a 3.57Mhz or 4Mhz crystal. Bad timekeeping will result from incorrect matching of the HEX file and crystal speed.
Gallery of other single numitron clocks:
These clocks were made by Terry, a fellow electronics hobbyist who bought 30 IV-6 numitrons off ebay and had to do something with them! I especially like the clock in the clear plastic tube case.
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