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6-digit Nixie clock [150189]

Status: Finished
August 24, 2015

This is a remake of the Simple Nixieclock (140013-1, see this project). After this project was published we got a lot of questions from our readers about changing the time zone, which was fixed to GMT+1 in the original design but could be altered in the source code of the PIC microcontroller. The author finally changed the firmware to set the time zone using a switch after reset.

We mentioned in the article that seconds were also counted but not displayed (after all: there were only four digits) and some readers were wondering if the design could be changed to show seconds as well. The PIC18F2480 doesn’t have enough I/O-pins for two extra digits and is replaced by a 40-pin DIP 18F4420. Apart from the two extra 74141’s, Nixie tubes plus an extra neon bulb for separating minutes and seconds digits, there are hardly any changes in the schematic, but of course the PCB layout needed to be redesigned. In the old design we used Russian IN-14 Nixies, but apparently even Ebay-shops in Eastern Europe are running out of stock. The prices have increased dramatically, making these tubes less suitable for new projects. We discussed this with Jan Wuesten, owner of the German tube-webshop (i.e. Ask Jan First), and decided to use IN-12 nixies in this design, which are pin compatible with other oval shaped nixie tubes like the ZM1100 and CD56. Since these are top view nixies, we made a separate PCB for the display that can be mounted perpendicular to another PCB containing the rest of the hardware. Six 10-way (box) headers (spaced on a 100mil grid) are used for the connection between the two boards, making it relatively easy to make your own display on vero board if you want to use other types of nixie tubes.

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