Single Numitron Clock

Home
Back to Projects Index

Numitrons are neat display devices similar to nixie tubes, but they were designed for low voltage use. Numitrons are basically incandescent displays, using filaments for the segments. I had just one RCA DR2100 Numitron, so I thought I'd make a single-digit clock out of it. The clock operates off a PIC 16F84A using a program written by David Tait (software is further down this page), and a 3.58 MHz color burst crystal salvaged from a VCR was used for the oscillator. Below is a schematic of the 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.

The .ASM file is the PIC assembly code and the .HEX file is the assembled file used to program the PIC. Note that the HEX files are assembled for the 3.57MHz crystal, but you may select the 4MHz option in the ASM file by commenting out (add a semicolon) #DEFINE _3_58MHZ and uncomment #DEFINE _4_00MHZ then reassemble a new HEX file using MPASM assembler, which can be downloaded off the internet.

24 Hour Numitron Clock (.ASM file)
24 Hour Numitron Clock (.HEX file)
12 Hour Numitron Clock (.ASM file)
12 Hour Numitron Clock (.HEX file)

Pictures:

The Single Numitron Clock

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.